/*

  * MPEG-1/2 decoder

  * Copyright (c) 2000,2001 Fabrice Bellard

  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>

  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.

  *

  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */

 /**

  * @file

  * MPEG-1/2 decoder

  */

 //#define DEBUG

 #include "internal.h"

 #include "avcodec.h"
 #include "dsputil.h"
 #include "mpegvideo.h"

 #include "libavutil/avassert.h"

 #include "mpeg12.h"

 #include "mpeg12data.h"

 #include "mpeg12decdata.h"

 #include "bytestream.h"

 #include "vdpau_internal.h"

 #include "xvmc_internal.h"

 #include "thread.h"

 //#undef NDEBUG
 //#include <assert.h>
 

 #define MV_VLC_BITS 9
 #define MBINCR_VLC_BITS 9
 #define MB_PAT_VLC_BITS 9
 #define MB_PTYPE_VLC_BITS 6
 #define MB_BTYPE_VLC_BITS 6
 

 static inline int mpeg1_decode_block_intra(MpegEncContext *s,
                               DCTELEM *block,
                               int n);

 static inline int mpeg1_decode_block_inter(MpegEncContext *s,
                               DCTELEM *block,

                               int n);

 static inline int mpeg1_fast_decode_block_inter(MpegEncContext *s, DCTELEM *block, int n);

 static inline int mpeg2_decode_block_non_intra(MpegEncContext *s,
                                         DCTELEM *block,

                                         int n);

 static inline int mpeg2_decode_block_intra(MpegEncContext *s,
                                     DCTELEM *block,

                                     int n);

 static inline int mpeg2_fast_decode_block_non_intra(MpegEncContext *s, DCTELEM *block, int n);

 static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s, DCTELEM *block, int n);

 static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred);

 static void exchange_uv(MpegEncContext *s);

 uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];

 
 #define INIT_2D_VLC_RL(rl, static_size)\
 {\
     static RL_VLC_ELEM rl_vlc_table[static_size];\
     INIT_VLC_STATIC(&rl.vlc, TEX_VLC_BITS, rl.n + 2,\
              &rl.table_vlc[0][1], 4, 2,\
              &rl.table_vlc[0][0], 4, 2, static_size);\
 \
     rl.rl_vlc[0]= rl_vlc_table;\
     init_2d_vlc_rl(&rl);\
 }
 

 static void init_2d_vlc_rl(RLTable *rl)

 {

     int i;

     for(i=0; i<rl->vlc.table_size; i++){
         int code= rl->vlc.table[i][0];
         int len = rl->vlc.table[i][1];
         int level, run;

         if(len==0){ // illegal code
             run= 65;
             level= MAX_LEVEL;
         }else if(len<0){ //more bits needed
             run= 0;
             level= code;
         }else{
             if(code==rl->n){ //esc
                 run= 65;
                 level= 0;
             }else if(code==rl->n+1){ //eob

                 run= 0;
                 level= 127;

             }else{
                 run=   rl->table_run  [code] + 1;
                 level= rl->table_level[code];
             }
         }
         rl->rl_vlc[0][i].len= len;
         rl->rl_vlc[0][i].level= level;
         rl->rl_vlc[0][i].run= run;
     }
 }
 

 void ff_mpeg12_common_init(MpegEncContext *s)

 {

     s->y_dc_scale_table=

     s->c_dc_scale_table= ff_mpeg2_dc_scale_table[s->intra_dc_precision];

 }

 void ff_mpeg1_clean_buffers(MpegEncContext *s){
     s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
     s->last_dc[1] = s->last_dc[0];
     s->last_dc[2] = s->last_dc[0];
     memset(s->last_mv, 0, sizeof(s->last_mv));
 }
 

 
 /******************************************/
 /* decoding */
 

 VLC ff_dc_lum_vlc;
 VLC ff_dc_chroma_vlc;
 

 static VLC mv_vlc;
 static VLC mbincr_vlc;
 static VLC mb_ptype_vlc;
 static VLC mb_btype_vlc;
 static VLC mb_pat_vlc;
 

 av_cold void ff_mpeg12_init_vlcs(void)

 {
     static int done = 0;
 
     if (!done) {

         done = 1;

         INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,

                  ff_mpeg12_vlc_dc_lum_bits, 1, 1,

                  ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);

         INIT_VLC_STATIC(&ff_dc_chroma_vlc,  DC_VLC_BITS, 12,

                  ff_mpeg12_vlc_dc_chroma_bits, 1, 1,

                  ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);
         INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 17,

                  &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,

                  &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);
         INIT_VLC_STATIC(&mbincr_vlc, MBINCR_VLC_BITS, 36,

                  &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,

                  &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);
         INIT_VLC_STATIC(&mb_pat_vlc, MB_PAT_VLC_BITS, 64,

                  &ff_mpeg12_mbPatTable[0][1], 2, 1,

                  &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);

         INIT_VLC_STATIC(&mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,

                  &table_mb_ptype[0][1], 2, 1,

                  &table_mb_ptype[0][0], 2, 1, 64);
         INIT_VLC_STATIC(&mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,

                  &table_mb_btype[0][1], 2, 1,

                  &table_mb_btype[0][0], 2, 1, 64);

         init_rl(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);
         init_rl(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);

         INIT_2D_VLC_RL(ff_rl_mpeg1, 680);
         INIT_2D_VLC_RL(ff_rl_mpeg2, 674);

     }
 }
 
 static inline int get_dmv(MpegEncContext *s)
 {

     if(get_bits1(&s->gb))

         return 1 - (get_bits1(&s->gb) << 1);

     else
         return 0;
 }
 

 static inline int get_qscale(MpegEncContext *s)
 {

     int qscale = get_bits(&s->gb, 5);

     if (s->q_scale_type) {
         return non_linear_qscale[qscale];
     } else {
         return qscale << 1;

     }
 }
 

 /* motion type (for MPEG-2) */

 #define MT_FIELD 1
 #define MT_FRAME 2
 #define MT_16X8  2
 #define MT_DMV   3
 
 static int mpeg_decode_mb(MpegEncContext *s,

                           DCTELEM block[12][64])

 {

     int i, j, k, cbp, val, mb_type, motion_type;

     const int mb_block_count = 4 + (1<< s->chroma_format);

     av_dlog(s->avctx, "decode_mb: x=%d y=%d\n", s->mb_x, s->mb_y);

     assert(s->mb_skipped==0);

     if (s->mb_skip_run-- != 0) {

         if (s->pict_type == AV_PICTURE_TYPE_P) {

             s->mb_skipped = 1;

             s->current_picture.mb_type[ s->mb_x + s->mb_y*s->mb_stride ]= MB_TYPE_SKIP | MB_TYPE_L0 | MB_TYPE_16x16;

         } else {

             int mb_type;

             if(s->mb_x)
                 mb_type= s->current_picture.mb_type[ s->mb_x + s->mb_y*s->mb_stride - 1];
             else

                 mb_type= s->current_picture.mb_type[ s->mb_width + (s->mb_y-1)*s->mb_stride - 1]; // FIXME not sure if this is allowed in MPEG at all

             if(IS_INTRA(mb_type))
                 return -1;

 
             s->current_picture.mb_type[ s->mb_x + s->mb_y*s->mb_stride ]=

                 mb_type | MB_TYPE_SKIP;

 //            assert(s->current_picture.mb_type[ s->mb_x + s->mb_y*s->mb_stride - 1]&(MB_TYPE_16x16|MB_TYPE_16x8));
 

             if((s->mv[0][0][0]|s->mv[0][0][1]|s->mv[1][0][0]|s->mv[1][0][1])==0)

                 s->mb_skipped = 1;

         }

         return 0;
     }
 
     switch(s->pict_type) {
     default:

     case AV_PICTURE_TYPE_I:

         if (get_bits1(&s->gb) == 0) {

             if (get_bits1(&s->gb) == 0){

                 av_log(s->avctx, AV_LOG_ERROR, "invalid mb type in I Frame at %d %d\n", s->mb_x, s->mb_y);

                 return -1;

             }

             mb_type = MB_TYPE_QUANT | MB_TYPE_INTRA;

         } else {

             mb_type = MB_TYPE_INTRA;

         }
         break;

     case AV_PICTURE_TYPE_P:

         mb_type = get_vlc2(&s->gb, mb_ptype_vlc.table, MB_PTYPE_VLC_BITS, 1);

         if (mb_type < 0){

             av_log(s->avctx, AV_LOG_ERROR, "invalid mb type in P Frame at %d %d\n", s->mb_x, s->mb_y);

             return -1;

         }

         mb_type = ptype2mb_type[ mb_type ];

         break;

     case AV_PICTURE_TYPE_B:

         mb_type = get_vlc2(&s->gb, mb_btype_vlc.table, MB_BTYPE_VLC_BITS, 1);

         if (mb_type < 0){

             av_log(s->avctx, AV_LOG_ERROR, "invalid mb type in B Frame at %d %d\n", s->mb_x, s->mb_y);

             return -1;

         }

         mb_type = btype2mb_type[ mb_type ];

         break;
     }

     av_dlog(s->avctx, "mb_type=%x\n", mb_type);

 //    motion_type = 0; /* avoid warning */
     if (IS_INTRA(mb_type)) {

         s->dsp.clear_blocks(s->block[0]);

         if(!s->chroma_y_shift){
             s->dsp.clear_blocks(s->block[6]);
         }

         /* compute DCT type */
         if (s->picture_structure == PICT_FRAME && //FIXME add an interlaced_dct coded var?

             !s->frame_pred_frame_dct) {
             s->interlaced_dct = get_bits1(&s->gb);
         }

         if (IS_QUANT(mb_type))
             s->qscale = get_qscale(s);

         if (s->concealment_motion_vectors) {
             /* just parse them */

             if (s->picture_structure != PICT_FRAME)

                 skip_bits1(&s->gb); /* field select */

 
             s->mv[0][0][0]= s->last_mv[0][0][0]= s->last_mv[0][1][0] =

                 mpeg_decode_motion(s, s->mpeg_f_code[0][0], s->last_mv[0][0][0]);

             s->mv[0][0][1]= s->last_mv[0][0][1]= s->last_mv[0][1][1] =

                 mpeg_decode_motion(s, s->mpeg_f_code[0][1], s->last_mv[0][0][1]);
 

             skip_bits1(&s->gb); /* marker */

         }else
             memset(s->last_mv, 0, sizeof(s->last_mv)); /* reset mv prediction */

         s->mb_intra = 1;

         //if 1, we memcpy blocks in xvmcvideo

         if(CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration > 1){

             ff_xvmc_pack_pblocks(s,-1);//inter are always full blocks

             if(s->swap_uv){
                 exchange_uv(s);
             }
         }

         if (s->codec_id == CODEC_ID_MPEG2VIDEO) {

             if(s->flags2 & CODEC_FLAG2_FAST){
                 for(i=0;i<6;i++) {

                     mpeg2_fast_decode_block_intra(s, *s->pblocks[i], i);

                 }
             }else{
                 for(i=0;i<mb_block_count;i++) {

                     if (mpeg2_decode_block_intra(s, *s->pblocks[i], i) < 0)

                         return -1;
                 }

             }
         } else {
             for(i=0;i<6;i++) {

                 if (mpeg1_decode_block_intra(s, *s->pblocks[i], i) < 0)

                     return -1;
             }
         }

     } else {

         if (mb_type & MB_TYPE_ZERO_MV){

             assert(mb_type & MB_TYPE_CBP);

 
             s->mv_dir = MV_DIR_FORWARD;

             if(s->picture_structure == PICT_FRAME){
                 if(!s->frame_pred_frame_dct)
                     s->interlaced_dct = get_bits1(&s->gb);

                 s->mv_type = MV_TYPE_16X16;

             }else{

                 s->mv_type = MV_TYPE_FIELD;
                 mb_type |= MB_TYPE_INTERLACED;
                 s->field_select[0][0]= s->picture_structure - 1;
             }

 
             if (IS_QUANT(mb_type))
                 s->qscale = get_qscale(s);
 

             s->last_mv[0][0][0] = 0;
             s->last_mv[0][0][1] = 0;
             s->last_mv[0][1][0] = 0;
             s->last_mv[0][1][1] = 0;
             s->mv[0][0][0] = 0;
             s->mv[0][0][1] = 0;
         }else{
             assert(mb_type & MB_TYPE_L0L1);
 //FIXME decide if MBs in field pictures are MB_TYPE_INTERLACED

             /* get additional motion vector type */

             if (s->frame_pred_frame_dct)

                 motion_type = MT_FRAME;
             else{
                 motion_type = get_bits(&s->gb, 2);

                 if (s->picture_structure == PICT_FRAME && HAS_CBP(mb_type))
                     s->interlaced_dct = get_bits1(&s->gb);

             }
 
             if (IS_QUANT(mb_type))
                 s->qscale = get_qscale(s);
 
             /* motion vectors */

             s->mv_dir= (mb_type>>13)&3;

             av_dlog(s->avctx, "motion_type=%d\n", motion_type);

             switch(motion_type) {
             case MT_FRAME: /* or MT_16X8 */

                 if (s->picture_structure == PICT_FRAME) {
                     mb_type |= MB_TYPE_16x16;
                     s->mv_type = MV_TYPE_16X16;
                     for(i=0;i<2;i++) {
                         if (USES_LIST(mb_type, i)) {

                             /* MT_FRAME */

                             s->mv[i][0][0]= s->last_mv[i][0][0]= s->last_mv[i][1][0] =

                                 mpeg_decode_motion(s, s->mpeg_f_code[i][0], s->last_mv[i][0][0]);

                             s->mv[i][0][1]= s->last_mv[i][0][1]= s->last_mv[i][1][1] =

                                 mpeg_decode_motion(s, s->mpeg_f_code[i][1], s->last_mv[i][0][1]);

                             /* full_pel: only for MPEG-1 */

                             if (s->full_pel[i]){
                                 s->mv[i][0][0] <<= 1;
                                 s->mv[i][0][1] <<= 1;
                             }

                         }
                     }
                 } else {
                     mb_type |= MB_TYPE_16x8 | MB_TYPE_INTERLACED;
                     s->mv_type = MV_TYPE_16X8;
                     for(i=0;i<2;i++) {
                         if (USES_LIST(mb_type, i)) {

                             /* MT_16X8 */
                             for(j=0;j<2;j++) {
                                 s->field_select[i][j] = get_bits1(&s->gb);
                                 for(k=0;k<2;k++) {
                                     val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],
                                                              s->last_mv[i][j][k]);
                                     s->last_mv[i][j][k] = val;
                                     s->mv[i][j][k] = val;
                                 }
                             }

                         }

                     }
                 }
                 break;
             case MT_FIELD:

                 if(s->progressive_sequence){
                     av_log(s->avctx, AV_LOG_ERROR, "MT_FIELD in progressive_sequence\n");
                     return -1;
                 }

                 s->mv_type = MV_TYPE_FIELD;

                 if (s->picture_structure == PICT_FRAME) {
                     mb_type |= MB_TYPE_16x8 | MB_TYPE_INTERLACED;
                     for(i=0;i<2;i++) {
                         if (USES_LIST(mb_type, i)) {

                             for(j=0;j<2;j++) {
                                 s->field_select[i][j] = get_bits1(&s->gb);
                                 val = mpeg_decode_motion(s, s->mpeg_f_code[i][0],
                                                          s->last_mv[i][j][0]);
                                 s->last_mv[i][j][0] = val;
                                 s->mv[i][j][0] = val;

                                 av_dlog(s->avctx, "fmx=%d\n", val);

                                 val = mpeg_decode_motion(s, s->mpeg_f_code[i][1],
                                                          s->last_mv[i][j][1] >> 1);
                                 s->last_mv[i][j][1] = val << 1;
                                 s->mv[i][j][1] = val;

                                 av_dlog(s->avctx, "fmy=%d\n", val);

                             }

                         }
                     }
                 } else {
                     mb_type |= MB_TYPE_16x16 | MB_TYPE_INTERLACED;
                     for(i=0;i<2;i++) {
                         if (USES_LIST(mb_type, i)) {

                             s->field_select[i][0] = get_bits1(&s->gb);

                             for(k=0;k<2;k++) {
                                 val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],

                                                          s->last_mv[i][0][k]);
                                 s->last_mv[i][0][k] = val;
                                 s->last_mv[i][1][k] = val;
                                 s->mv[i][0][k] = val;

                             }
                         }

                     }
                 }
                 break;
             case MT_DMV:

                 if(s->progressive_sequence){
                     av_log(s->avctx, AV_LOG_ERROR, "MT_DMV in progressive_sequence\n");
                     return -1;
                 }

                 s->mv_type = MV_TYPE_DMV;
                 for(i=0;i<2;i++) {
                     if (USES_LIST(mb_type, i)) {
                         int dmx, dmy, mx, my, m;

                         const int my_shift= s->picture_structure == PICT_FRAME;
 

                         mx = mpeg_decode_motion(s, s->mpeg_f_code[i][0],
                                                 s->last_mv[i][0][0]);
                         s->last_mv[i][0][0] = mx;
                         s->last_mv[i][1][0] = mx;
                         dmx = get_dmv(s);
                         my = mpeg_decode_motion(s, s->mpeg_f_code[i][1],

                                                 s->last_mv[i][0][1] >> my_shift);

                         dmy = get_dmv(s);
 
 

                         s->last_mv[i][0][1] = my<<my_shift;
                         s->last_mv[i][1][1] = my<<my_shift;

 
                         s->mv[i][0][0] = mx;
                         s->mv[i][0][1] = my;
                         s->mv[i][1][0] = mx;//not used
                         s->mv[i][1][1] = my;//not used
 
                         if (s->picture_structure == PICT_FRAME) {
                             mb_type |= MB_TYPE_16x16 | MB_TYPE_INTERLACED;
 
                             //m = 1 + 2 * s->top_field_first;
                             m = s->top_field_first ? 1 : 3;
 
                             /* top -> top pred */
                             s->mv[i][2][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
                             s->mv[i][2][1] = ((my * m + (my > 0)) >> 1) + dmy - 1;
                             m = 4 - m;
                             s->mv[i][3][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
                             s->mv[i][3][1] = ((my * m + (my > 0)) >> 1) + dmy + 1;
                         } else {
                             mb_type |= MB_TYPE_16x16;
 
                             s->mv[i][2][0] = ((mx + (mx > 0)) >> 1) + dmx;
                             s->mv[i][2][1] = ((my + (my > 0)) >> 1) + dmy;
                             if(s->picture_structure == PICT_TOP_FIELD)
                                 s->mv[i][2][1]--;
                             else
                                 s->mv[i][2][1]++;

                         }
                     }
                 }

                 break;
             default:
                 av_log(s->avctx, AV_LOG_ERROR, "00 motion_type at %d %d\n", s->mb_x, s->mb_y);
                 return -1;

             }
         }

         s->mb_intra = 0;

         if (HAS_CBP(mb_type)) {

             s->dsp.clear_blocks(s->block[0]);

             cbp = get_vlc2(&s->gb, mb_pat_vlc.table, MB_PAT_VLC_BITS, 1);

             if(mb_block_count > 6){

                  cbp<<= mb_block_count-6;
                  cbp |= get_bits(&s->gb, mb_block_count-6);

                  s->dsp.clear_blocks(s->block[6]);

             }

             if (cbp <= 0){
                 av_log(s->avctx, AV_LOG_ERROR, "invalid cbp at %d %d\n", s->mb_x, s->mb_y);
                 return -1;
             }

             //if 1, we memcpy blocks in xvmcvideo

             if(CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration > 1){

                 ff_xvmc_pack_pblocks(s,cbp);

                 if(s->swap_uv){
                     exchange_uv(s);
                 }

             }

             if (s->codec_id == CODEC_ID_MPEG2VIDEO) {

                 if(s->flags2 & CODEC_FLAG2_FAST){
                     for(i=0;i<6;i++) {
                         if(cbp & 32) {

                             mpeg2_fast_decode_block_non_intra(s, *s->pblocks[i], i);

                         } else {
                             s->block_last_index[i] = -1;
                         }
                         cbp+=cbp;
                     }
                 }else{
                     cbp<<= 12-mb_block_count;

                     for(i=0;i<mb_block_count;i++) {
                         if ( cbp & (1<<11) ) {

                             if (mpeg2_decode_block_non_intra(s, *s->pblocks[i], i) < 0)

                                 return -1;
                         } else {
                             s->block_last_index[i] = -1;
                         }
                         cbp+=cbp;

                     }

                 }

             } else {

                 if(s->flags2 & CODEC_FLAG2_FAST){
                     for(i=0;i<6;i++) {
                         if (cbp & 32) {

                             mpeg1_fast_decode_block_inter(s, *s->pblocks[i], i);

                         } else {
                             s->block_last_index[i] = -1;
                         }
                         cbp+=cbp;
                     }
                 }else{
                     for(i=0;i<6;i++) {
                         if (cbp & 32) {

                             if (mpeg1_decode_block_inter(s, *s->pblocks[i], i) < 0)

                                 return -1;
                         } else {
                             s->block_last_index[i] = -1;
                         }
                         cbp+=cbp;

                     }

                 }

             }

         }else{

             for(i=0;i<12;i++)

                 s->block_last_index[i] = -1;

         }
     }

 
     s->current_picture.mb_type[ s->mb_x + s->mb_y*s->mb_stride ]= mb_type;
 

     return 0;
 }
 

 /* as H.263, but only 17 codes */

 static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)
 {

     int code, sign, val, l, shift;

     code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);

     if (code == 0) {
         return pred;
     }

     if (code < 0) {
         return 0xffff;
     }
 

     sign = get_bits1(&s->gb);

     shift = fcode - 1;

     val = code;
     if (shift) {
         val = (val - 1) << shift;

         val |= get_bits(&s->gb, shift);

         val++;
     }

     if (sign)
         val = -val;
     val += pred;

     /* modulo decoding */

     l= INT_BIT - 5 - shift;
     val = (val<<l)>>l;

     return val;
 }
 

 static inline int mpeg1_decode_block_intra(MpegEncContext *s,

                                DCTELEM *block,

                                int n)
 {
     int level, dc, diff, i, j, run;

     int component;

     RLTable *rl = &ff_rl_mpeg1;

     uint8_t * const scantable= s->intra_scantable.permutated;
     const uint16_t *quant_matrix= s->intra_matrix;

     const int qscale= s->qscale;

     /* DC coefficient */

     component = (n <= 3 ? 0 : n - 4 + 1);

     diff = decode_dc(&s->gb, component);

     if (diff >= 0xffff)
         return -1;
     dc = s->last_dc[component];
     dc += diff;
     s->last_dc[component] = dc;

     block[0] = dc*quant_matrix[0];

     av_dlog(s->avctx, "dc=%d diff=%d\n", dc, diff);

     i = 0;
     {

         OPEN_READER(re, &s->gb);

         /* now quantify & encode AC coefficients */

         for(;;) {
             UPDATE_CACHE(re, &s->gb);

             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

             if(level == 127){
                 break;
             } else if(level != 0) {
                 i += run;
                 j = scantable[i];

                 level= (level*qscale*quant_matrix[j])>>4;

                 level= (level-1)|1;
                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                 LAST_SKIP_BITS(re, &s->gb, 1);
             } else {
                 /* escape */
                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                 UPDATE_CACHE(re, &s->gb);
                 level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8);
                 if (level == -128) {
                     level = SHOW_UBITS(re, &s->gb, 8) - 256; LAST_SKIP_BITS(re, &s->gb, 8);
                 } else if (level == 0) {
                     level = SHOW_UBITS(re, &s->gb, 8)      ; LAST_SKIP_BITS(re, &s->gb, 8);
                 }
                 i += run;
                 j = scantable[i];
                 if(level<0){
                     level= -level;

                     level= (level*qscale*quant_matrix[j])>>4;

                     level= (level-1)|1;
                     level= -level;
                 }else{

                     level= (level*qscale*quant_matrix[j])>>4;

                     level= (level-1)|1;
                 }
             }
             if (i > 63){

                 av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);

                 return -1;
             }
 
             block[j] = level;
         }
         CLOSE_READER(re, &s->gb);
     }
     s->block_last_index[n] = i;
    return 0;
 }
 

 int ff_mpeg1_decode_block_intra(MpegEncContext *s,
                                 DCTELEM *block,
                                 int n)
 {
     return mpeg1_decode_block_intra(s, block, n);
 }
 

 static inline int mpeg1_decode_block_inter(MpegEncContext *s,
                                DCTELEM *block,

                                int n)
 {
     int level, i, j, run;

     RLTable *rl = &ff_rl_mpeg1;

     uint8_t * const scantable= s->intra_scantable.permutated;
     const uint16_t *quant_matrix= s->inter_matrix;

     const int qscale= s->qscale;
 
     {

         OPEN_READER(re, &s->gb);

         i = -1;

         // special case for first coefficient, no need to add second VLC table

         UPDATE_CACHE(re, &s->gb);

         if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {

             level= (3*qscale*quant_matrix[0])>>5;

             level= (level-1)|1;

             if(GET_CACHE(re, &s->gb)&0x40000000)

                 level= -level;

             block[0] = level;

             i++;

             SKIP_BITS(re, &s->gb, 2);
             if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                 goto end;

         }

         /* now quantify & encode AC coefficients */

         for(;;) {

             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

             if(level != 0) {

                 i += run;
                 j = scantable[i];

                 level= ((level*2+1)*qscale*quant_matrix[j])>>5;

                 level= (level-1)|1;
                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);

                 SKIP_BITS(re, &s->gb, 1);

             } else {
                 /* escape */
                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                 UPDATE_CACHE(re, &s->gb);
                 level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8);
                 if (level == -128) {

                     level = SHOW_UBITS(re, &s->gb, 8) - 256; SKIP_BITS(re, &s->gb, 8);

                 } else if (level == 0) {

                     level = SHOW_UBITS(re, &s->gb, 8)      ; SKIP_BITS(re, &s->gb, 8);

                 }
                 i += run;
                 j = scantable[i];
                 if(level<0){
                     level= -level;

                     level= ((level*2+1)*qscale*quant_matrix[j])>>5;

                     level= (level-1)|1;
                     level= -level;
                 }else{

                     level= ((level*2+1)*qscale*quant_matrix[j])>>5;

                     level= (level-1)|1;
                 }

             }

             if (i > 63){

                 av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);

                 return -1;
             }
 
             block[j] = level;

             if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                 break;
             UPDATE_CACHE(re, &s->gb);

         }

 end:
         LAST_SKIP_BITS(re, &s->gb, 2);

         CLOSE_READER(re, &s->gb);

     }

     s->block_last_index[n] = i;

     return 0;
 }
 

 static inline int mpeg1_fast_decode_block_inter(MpegEncContext *s, DCTELEM *block, int n)
 {
     int level, i, j, run;

     RLTable *rl = &ff_rl_mpeg1;

     uint8_t * const scantable= s->intra_scantable.permutated;
     const int qscale= s->qscale;
 
     {
         OPEN_READER(re, &s->gb);
         i = -1;

         // special case for first coefficient, no need to add second VLC table

         UPDATE_CACHE(re, &s->gb);

         if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {

             level= (3*qscale)>>1;

             level= (level-1)|1;

             if(GET_CACHE(re, &s->gb)&0x40000000)

                 level= -level;
             block[0] = level;
             i++;

             SKIP_BITS(re, &s->gb, 2);
             if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                 goto end;

         }
 

         /* now quantify & encode AC coefficients */

         for(;;) {

             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

             if(level != 0) {

                 i += run;
                 j = scantable[i];
                 level= ((level*2+1)*qscale)>>1;
                 level= (level-1)|1;
                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);

                 SKIP_BITS(re, &s->gb, 1);

             } else {
                 /* escape */
                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                 UPDATE_CACHE(re, &s->gb);
                 level = SHOW_SBITS(re, &s->gb, 8); SKIP_BITS(re, &s->gb, 8);
                 if (level == -128) {

                     level = SHOW_UBITS(re, &s->gb, 8) - 256; SKIP_BITS(re, &s->gb, 8);

                 } else if (level == 0) {

                     level = SHOW_UBITS(re, &s->gb, 8)      ; SKIP_BITS(re, &s->gb, 8);

                 }
                 i += run;
                 j = scantable[i];
                 if(level<0){
                     level= -level;
                     level= ((level*2+1)*qscale)>>1;
                     level= (level-1)|1;
                     level= -level;
                 }else{
                     level= ((level*2+1)*qscale)>>1;
                     level= (level-1)|1;
                 }
             }
 
             block[j] = level;

             if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                 break;
             UPDATE_CACHE(re, &s->gb);

         }

 end:
         LAST_SKIP_BITS(re, &s->gb, 2);

         CLOSE_READER(re, &s->gb);
     }
     s->block_last_index[n] = i;
     return 0;
 }
 
 

 static inline int mpeg2_decode_block_non_intra(MpegEncContext *s,
                                DCTELEM *block,

                                int n)

 {
     int level, i, j, run;

     RLTable *rl = &ff_rl_mpeg1;

     uint8_t * const scantable= s->intra_scantable.permutated;
     const uint16_t *quant_matrix;

     const int qscale= s->qscale;

     int mismatch;
 
     mismatch = 1;
 
     {

         OPEN_READER(re, &s->gb);

         i = -1;

         if (n < 4)

             quant_matrix = s->inter_matrix;

         else

             quant_matrix = s->chroma_inter_matrix;

         // special case for first coefficient, no need to add second VLC table

         UPDATE_CACHE(re, &s->gb);

         if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {

             level= (3*qscale*quant_matrix[0])>>5;

             if(GET_CACHE(re, &s->gb)&0x40000000)

                 level= -level;
             block[0] = level;
             mismatch ^= level;
             i++;

             SKIP_BITS(re, &s->gb, 2);
             if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                 goto end;

         }
 

         /* now quantify & encode AC coefficients */

         for(;;) {

             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

             if(level != 0) {

                 i += run;
                 j = scantable[i];
                 level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);

                 SKIP_BITS(re, &s->gb, 1);

             } else {
                 /* escape */
                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                 UPDATE_CACHE(re, &s->gb);
                 level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
 
                 i += run;
                 j = scantable[i];
                 if(level<0){
                     level= ((-level*2+1)*qscale*quant_matrix[j])>>5;
                     level= -level;
                 }else{
                     level= ((level*2+1)*qscale*quant_matrix[j])>>5;
                 }
             }
             if (i > 63){

                 av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);

                 return -1;
             }

             mismatch ^= level;
             block[j] = level;

             if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
                 break;
             UPDATE_CACHE(re, &s->gb);

         }

 end:
         LAST_SKIP_BITS(re, &s->gb, 2);

         CLOSE_READER(re, &s->gb);

     }
     block[63] ^= (mismatch & 1);

     s->block_last_index[n] = i;
     return 0;
 }
 

 static inline int mpeg2_fast_decode_block_non_intra(MpegEncContext *s,
                                DCTELEM *block,

                                int n)
 {
     int level, i, j, run;

     RLTable *rl = &ff_rl_mpeg1;

     uint8_t * const scantable= s->intra_scantable.permutated;
     const int qscale= s->qscale;
     OPEN_READER(re, &s->gb);
     i = -1;
 

     // special case for first coefficient, no need to add second VLC table

     UPDATE_CACHE(re, &s->gb);

     if (((int32_t)GET_CACHE(re, &s->gb)) < 0) {

         level= (3*qscale)>>1;

         if(GET_CACHE(re, &s->gb)&0x40000000)

             level= -level;
         block[0] = level;
         i++;

         SKIP_BITS(re, &s->gb, 2);
         if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
             goto end;

     }
 

     /* now quantify & encode AC coefficients */

     for(;;) {

         GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

         if(level != 0) {

             i += run;
             j = scantable[i];
             level= ((level*2+1)*qscale)>>1;
             level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);

             SKIP_BITS(re, &s->gb, 1);

         } else {
             /* escape */
             run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
             UPDATE_CACHE(re, &s->gb);
             level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
 
             i += run;
             j = scantable[i];
             if(level<0){
                 level= ((-level*2+1)*qscale)>>1;
                 level= -level;
             }else{
                 level= ((level*2+1)*qscale)>>1;
             }
         }

         block[j] = level;

         if(((int32_t)GET_CACHE(re, &s->gb)) <= (int32_t)0xBFFFFFFF)
             break;
         UPDATE_CACHE(re, &s->gb);

     }

 end:

     LAST_SKIP_BITS(re, &s->gb, 2);

     CLOSE_READER(re, &s->gb);
     s->block_last_index[n] = i;
     return 0;
 }
 
 

 static inline int mpeg2_decode_block_intra(MpegEncContext *s,
                                DCTELEM *block,

                                int n)

 {
     int level, dc, diff, i, j, run;

     int component;

     RLTable *rl;

     uint8_t * const scantable= s->intra_scantable.permutated;
     const uint16_t *quant_matrix;

     const int qscale= s->qscale;

     int mismatch;
 

     /* DC coefficient */

     if (n < 4){
         quant_matrix = s->intra_matrix;

         component = 0;

     }else{
         quant_matrix = s->chroma_intra_matrix;

         component = (n&1) + 1;

     }

     diff = decode_dc(&s->gb, component);

     if (diff >= 0xffff)
         return -1;
     dc = s->last_dc[component];
     dc += diff;
     s->last_dc[component] = dc;
     block[0] = dc << (3 - s->intra_dc_precision);

     av_dlog(s->avctx, "dc=%d\n", block[0]);

     mismatch = block[0] ^ 1;

     i = 0;

     if (s->intra_vlc_format)

         rl = &ff_rl_mpeg2;

     else

         rl = &ff_rl_mpeg1;

     {

         OPEN_READER(re, &s->gb);

         /* now quantify & encode AC coefficients */

         for(;;) {
             UPDATE_CACHE(re, &s->gb);

             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

             if(level == 127){
                 break;
             } else if(level != 0) {
                 i += run;
                 j = scantable[i];
                 level= (level*qscale*quant_matrix[j])>>4;
                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                 LAST_SKIP_BITS(re, &s->gb, 1);
             } else {
                 /* escape */
                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                 UPDATE_CACHE(re, &s->gb);
                 level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
                 i += run;
                 j = scantable[i];
                 if(level<0){
                     level= (-level*qscale*quant_matrix[j])>>4;
                     level= -level;
                 }else{
                     level= (level*qscale*quant_matrix[j])>>4;
                 }
             }
             if (i > 63){

                 av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);

                 return -1;
             }

             mismatch^= level;
             block[j] = level;

         }

         CLOSE_READER(re, &s->gb);

     }

     block[63]^= mismatch&1;

     s->block_last_index[n] = i;
     return 0;
 }
 

 static inline int mpeg2_fast_decode_block_intra(MpegEncContext *s,
                                DCTELEM *block,

                                int n)
 {
     int level, dc, diff, j, run;
     int component;
     RLTable *rl;
     uint8_t * scantable= s->intra_scantable.permutated;
     const uint16_t *quant_matrix;
     const int qscale= s->qscale;
 

     /* DC coefficient */

     if (n < 4){
         quant_matrix = s->intra_matrix;

         component = 0;

     }else{
         quant_matrix = s->chroma_intra_matrix;
         component = (n&1) + 1;
     }
     diff = decode_dc(&s->gb, component);
     if (diff >= 0xffff)
         return -1;
     dc = s->last_dc[component];
     dc += diff;
     s->last_dc[component] = dc;
     block[0] = dc << (3 - s->intra_dc_precision);
     if (s->intra_vlc_format)

         rl = &ff_rl_mpeg2;

     else

         rl = &ff_rl_mpeg1;

 
     {

         OPEN_READER(re, &s->gb);

         /* now quantify & encode AC coefficients */

         for(;;) {
             UPDATE_CACHE(re, &s->gb);
             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

             if(level == 127){
                 break;
             } else if(level != 0) {
                 scantable += run;
                 j = *scantable;
                 level= (level*qscale*quant_matrix[j])>>4;
                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                 LAST_SKIP_BITS(re, &s->gb, 1);
             } else {
                 /* escape */
                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
                 UPDATE_CACHE(re, &s->gb);
                 level = SHOW_SBITS(re, &s->gb, 12); SKIP_BITS(re, &s->gb, 12);
                 scantable += run;
                 j = *scantable;
                 if(level<0){
                     level= (-level*qscale*quant_matrix[j])>>4;
                     level= -level;
                 }else{
                     level= (level*qscale*quant_matrix[j])>>4;
                 }
             }

             block[j] = level;
         }
         CLOSE_READER(re, &s->gb);
     }

     s->block_last_index[n] = scantable - s->intra_scantable.permutated;
     return 0;
 }
 

 typedef struct Mpeg1Context {
     MpegEncContext mpeg_enc_ctx;
     int mpeg_enc_ctx_allocated; /* true if decoding context allocated */

     int repeat_field; /* true if we must repeat the field */

     AVPanScan pan_scan;              /**< some temporary storage for the panscan */

     int slice_count;

     int swap_uv;//indicate VCR2
     int save_aspect_info;

     int save_width, save_height, save_progressive_seq;

     AVRational frame_rate_ext;       ///< MPEG-2 specific framerate modificator

     int sync;                        ///< Did we reach a sync point like a GOP/SEQ/KEYFrame?

 } Mpeg1Context;
 

 static av_cold int mpeg_decode_init(AVCodecContext *avctx)

 {
     Mpeg1Context *s = avctx->priv_data;

     MpegEncContext *s2 = &s->mpeg_enc_ctx;

     int i;

     /* we need some permutation to store matrices,
      * until MPV_common_init() sets the real permutation. */

     for(i=0;i<64;i++)
        s2->dsp.idct_permutation[i]=i;
 

     MPV_decode_defaults(s2);

     s->mpeg_enc_ctx.avctx= avctx;

     s->mpeg_enc_ctx.flags= avctx->flags;

     s->mpeg_enc_ctx.flags2= avctx->flags2;

     ff_mpeg12_common_init(&s->mpeg_enc_ctx);

     ff_mpeg12_init_vlcs();

 
     s->mpeg_enc_ctx_allocated = 0;
     s->mpeg_enc_ctx.picture_number = 0;

     s->repeat_field = 0;

     s->mpeg_enc_ctx.codec_id= avctx->codec->id;

     avctx->color_range= AVCOL_RANGE_MPEG;

     if (avctx->codec->id == CODEC_ID_MPEG1VIDEO)
         avctx->chroma_sample_location = AVCHROMA_LOC_CENTER;
     else
         avctx->chroma_sample_location = AVCHROMA_LOC_LEFT;

     return 0;
 }
 

 static int mpeg_decode_update_thread_context(AVCodecContext *avctx, const AVCodecContext *avctx_from)
 {
     Mpeg1Context *ctx = avctx->priv_data, *ctx_from = avctx_from->priv_data;
     MpegEncContext *s = &ctx->mpeg_enc_ctx, *s1 = &ctx_from->mpeg_enc_ctx;
     int err;
 
     if(avctx == avctx_from || !ctx_from->mpeg_enc_ctx_allocated || !s1->context_initialized)
         return 0;
 
     err = ff_mpeg_update_thread_context(avctx, avctx_from);
     if(err) return err;
 
     if(!ctx->mpeg_enc_ctx_allocated)
         memcpy(s + 1, s1 + 1, sizeof(Mpeg1Context) - sizeof(MpegEncContext));
 

     if(!(s->pict_type == AV_PICTURE_TYPE_B || s->low_delay))

         s->picture_number++;
 
     return 0;
 }
 

 static void quant_matrix_rebuild(uint16_t *matrix, const uint8_t *old_perm,

                                      const uint8_t *new_perm){

     uint16_t temp_matrix[64];
     int i;

 
     memcpy(temp_matrix,matrix,64*sizeof(uint16_t));

     for(i=0;i<64;i++){
         matrix[new_perm[i]] = temp_matrix[old_perm[i]];

     }

 }
 

 static const enum PixelFormat mpeg1_hwaccel_pixfmt_list_420[] = {

 #if CONFIG_MPEG_XVMC_DECODER

     PIX_FMT_XVMC_MPEG2_IDCT,
     PIX_FMT_XVMC_MPEG2_MC,

 #endif
 #if CONFIG_MPEG1_VDPAU_HWACCEL

     PIX_FMT_VDPAU_MPEG1,

 #endif

     PIX_FMT_YUV420P,
     PIX_FMT_NONE
 };
 
 static const enum PixelFormat mpeg2_hwaccel_pixfmt_list_420[] = {

 #if CONFIG_MPEG_XVMC_DECODER

     PIX_FMT_XVMC_MPEG2_IDCT,
     PIX_FMT_XVMC_MPEG2_MC,

 #endif
 #if CONFIG_MPEG2_VDPAU_HWACCEL

     PIX_FMT_VDPAU_MPEG2,

 #endif
 #if CONFIG_MPEG2_DXVA2_HWACCEL

     PIX_FMT_DXVA2_VLD,

 #endif
 #if CONFIG_MPEG2_VAAPI_HWACCEL

     PIX_FMT_VAAPI_VLD,

 #endif

     PIX_FMT_YUV420P,
     PIX_FMT_NONE
 };
 
 static inline int uses_vdpau(AVCodecContext *avctx) {
     return avctx->pix_fmt == PIX_FMT_VDPAU_MPEG1 || avctx->pix_fmt == PIX_FMT_VDPAU_MPEG2;
 }
 

 static enum PixelFormat mpeg_get_pixelformat(AVCodecContext *avctx){

     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;
 

     if(s->chroma_format < 2) {
         enum PixelFormat res;
         res = avctx->get_format(avctx,
                                 avctx->codec_id == CODEC_ID_MPEG1VIDEO ?
                                 mpeg1_hwaccel_pixfmt_list_420 :
                                 mpeg2_hwaccel_pixfmt_list_420);
         if (res != PIX_FMT_XVMC_MPEG2_IDCT && res != PIX_FMT_XVMC_MPEG2_MC) {
             avctx->xvmc_acceleration = 0;
         } else if (!avctx->xvmc_acceleration) {
             avctx->xvmc_acceleration = 2;
         }
         return res;
     } else if(s->chroma_format == 2)
         return PIX_FMT_YUV422P;
     else
         return PIX_FMT_YUV444P;

 }
 

 /* Call this function when we know all parameters.
  * It may be called in different places for MPEG-1 and MPEG-2. */

 static int mpeg_decode_postinit(AVCodecContext *avctx){

     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;
     uint8_t old_permutation[64];

 
     if (

         (s1->mpeg_enc_ctx_allocated == 0)||

         avctx->coded_width  != s->width ||
         avctx->coded_height != s->height||

         s1->save_width != s->width ||
         s1->save_height != s->height ||

         s1->save_aspect_info != s->aspect_ratio_info||

         s1->save_progressive_seq != s->progressive_sequence ||

         0)
     {

         if (s1->mpeg_enc_ctx_allocated) {

             ParseContext pc= s->parse_context;
             s->parse_context.buffer=0;

             MPV_common_end(s);

             s->parse_context= pc;

         }
 

         if( (s->width == 0 )||(s->height == 0))
             return -2;

         avcodec_set_dimensions(avctx, s->width, s->height);

         avctx->bit_rate = s->bit_rate;
         s1->save_aspect_info = s->aspect_ratio_info;

         s1->save_width = s->width;
         s1->save_height = s->height;

         s1->save_progressive_seq = s->progressive_sequence;

         /* low_delay may be forced, in this case we will have B-frames
          * that behave like P-frames. */

         avctx->has_b_frames = !(s->low_delay);
 

         assert((avctx->sub_id==1) == (avctx->codec_id==CODEC_ID_MPEG1VIDEO));
         if(avctx->codec_id==CODEC_ID_MPEG1VIDEO){

             //MPEG-1 fps

             avctx->time_base.den= ff_frame_rate_tab[s->frame_rate_index].num;
             avctx->time_base.num= ff_frame_rate_tab[s->frame_rate_index].den;

             //MPEG-1 aspect

             avctx->sample_aspect_ratio= av_d2q(

                     1.0/ff_mpeg1_aspect[s->aspect_ratio_info], 255);

             avctx->ticks_per_frame=1;

         }else{//MPEG-2
         //MPEG-2 fps

             av_reduce(

                 &s->avctx->time_base.den,
                 &s->avctx->time_base.num,

                 ff_frame_rate_tab[s->frame_rate_index].num * s1->frame_rate_ext.num*2,

                 ff_frame_rate_tab[s->frame_rate_index].den * s1->frame_rate_ext.den,

                 1<<30);

             avctx->ticks_per_frame=2;

         //MPEG-2 aspect

             if(s->aspect_ratio_info > 1){

                 AVRational dar =

                     av_mul_q(

                         av_div_q(ff_mpeg2_aspect[s->aspect_ratio_info],
                                  (AVRational){s1->pan_scan.width, s1->pan_scan.height}),

                         (AVRational){s->width, s->height});
 

                 // we ignore the spec here and guess a bit as reality does not match the spec, see for example

                 // res_change_ffmpeg_aspect.ts and sequence-display-aspect.mpg

                 // issue1613, 621, 562
                 if((s1->pan_scan.width == 0 ) || (s1->pan_scan.height == 0) ||
                    (av_cmp_q(dar,(AVRational){4,3}) && av_cmp_q(dar,(AVRational){16,9}))) {

                     s->avctx->sample_aspect_ratio=

                         av_div_q(

                          ff_mpeg2_aspect[s->aspect_ratio_info],

                          (AVRational){s->width, s->height}
                          );

                 }else{

                     s->avctx->sample_aspect_ratio=

                         av_div_q(

                          ff_mpeg2_aspect[s->aspect_ratio_info],

                          (AVRational){s1->pan_scan.width, s1->pan_scan.height}

                         );

 //issue1613 4/3 16/9 -> 16/9
 //res_change_ffmpeg_aspect.ts 4/3 225/44 ->4/3
 //widescreen-issue562.mpg 4/3 16/9 -> 16/9
 //                    s->avctx->sample_aspect_ratio= av_mul_q(s->avctx->sample_aspect_ratio, (AVRational){s->width, s->height});
 //av_log(NULL, AV_LOG_ERROR, "A %d/%d\n",ff_mpeg2_aspect[s->aspect_ratio_info].num, ff_mpeg2_aspect[s->aspect_ratio_info].den);
 //av_log(NULL, AV_LOG_ERROR, "B %d/%d\n",s->avctx->sample_aspect_ratio.num, s->avctx->sample_aspect_ratio.den);

                 }

             }else{

                 s->avctx->sample_aspect_ratio=

                     ff_mpeg2_aspect[s->aspect_ratio_info];

             }

         }//MPEG-2

         avctx->pix_fmt = mpeg_get_pixelformat(avctx);

         avctx->hwaccel = ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);

         //until then pix_fmt may be changed right after codec init

         if( avctx->pix_fmt == PIX_FMT_XVMC_MPEG2_IDCT ||

             avctx->hwaccel )

             if( avctx->idct_algo == FF_IDCT_AUTO )
                 avctx->idct_algo = FF_IDCT_SIMPLE;
 

         /* Quantization matrices may need reordering
          * if DCT permutation is changed. */

         memcpy(old_permutation,s->dsp.idct_permutation,64*sizeof(uint8_t));
 
         if (MPV_common_init(s) < 0)
             return -2;
 
         quant_matrix_rebuild(s->intra_matrix,       old_permutation,s->dsp.idct_permutation);
         quant_matrix_rebuild(s->inter_matrix,       old_permutation,s->dsp.idct_permutation);
         quant_matrix_rebuild(s->chroma_intra_matrix,old_permutation,s->dsp.idct_permutation);
         quant_matrix_rebuild(s->chroma_inter_matrix,old_permutation,s->dsp.idct_permutation);
 
         s1->mpeg_enc_ctx_allocated = 1;
     }
     return 0;
 }
 

 static int mpeg1_decode_picture(AVCodecContext *avctx,

                                 const uint8_t *buf, int buf_size)

 {
     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;

     int ref, f_code, vbv_delay;

     init_get_bits(&s->gb, buf, buf_size*8);

 
     ref = get_bits(&s->gb, 10); /* temporal ref */
     s->pict_type = get_bits(&s->gb, 3);

     if(s->pict_type == 0 || s->pict_type > 3)
         return -1;

     vbv_delay= get_bits(&s->gb, 16);

     if (s->pict_type == AV_PICTURE_TYPE_P || s->pict_type == AV_PICTURE_TYPE_B) {

         s->full_pel[0] = get_bits1(&s->gb);

         f_code = get_bits(&s->gb, 3);

         if (f_code == 0 && avctx->error_recognition >= FF_ER_COMPLIANT)

             return -1;
         s->mpeg_f_code[0][0] = f_code;
         s->mpeg_f_code[0][1] = f_code;
     }

     if (s->pict_type == AV_PICTURE_TYPE_B) {

         s->full_pel[1] = get_bits1(&s->gb);

         f_code = get_bits(&s->gb, 3);

         if (f_code == 0 && avctx->error_recognition >= FF_ER_COMPLIANT)

             return -1;
         s->mpeg_f_code[1][0] = f_code;
         s->mpeg_f_code[1][1] = f_code;
     }

     s->current_picture.pict_type= s->pict_type;

     s->current_picture.key_frame= s->pict_type == AV_PICTURE_TYPE_I;

     if(avctx->debug & FF_DEBUG_PICT_INFO)
         av_log(avctx, AV_LOG_DEBUG, "vbv_delay %d, ref %d type:%d\n", vbv_delay, ref, s->pict_type);

     s->y_dc_scale = 8;
     s->c_dc_scale = 8;
     return 0;
 }
 

 static void mpeg_decode_sequence_extension(Mpeg1Context *s1)

 {

     MpegEncContext *s= &s1->mpeg_enc_ctx;

     int horiz_size_ext, vert_size_ext;

     int bit_rate_ext;

     skip_bits(&s->gb, 1); /* profile and level esc*/

     s->avctx->profile= get_bits(&s->gb, 3);
     s->avctx->level= get_bits(&s->gb, 4);

     s->progressive_sequence = get_bits1(&s->gb); /* progressive_sequence */

     s->chroma_format = get_bits(&s->gb, 2); /* chroma_format 1=420, 2=422, 3=444 */

     horiz_size_ext = get_bits(&s->gb, 2);
     vert_size_ext = get_bits(&s->gb, 2);
     s->width |= (horiz_size_ext << 12);
     s->height |= (vert_size_ext << 12);
     bit_rate_ext = get_bits(&s->gb, 12);  /* XXX: handle it */

     s->bit_rate += (bit_rate_ext << 18) * 400;

     skip_bits1(&s->gb); /* marker */

     s->avctx->rc_buffer_size += get_bits(&s->gb, 8)*1024*16<<10;

     s->low_delay = get_bits1(&s->gb);

     if(s->flags & CODEC_FLAG_LOW_DELAY) s->low_delay=1;
 

     s1->frame_rate_ext.num = get_bits(&s->gb, 2)+1;
     s1->frame_rate_ext.den = get_bits(&s->gb, 5)+1;

     av_dlog(s->avctx, "sequence extension\n");

     s->codec_id= s->avctx->codec_id= CODEC_ID_MPEG2VIDEO;

     s->avctx->sub_id = 2; /* indicates MPEG-2 found */

     if(s->avctx->debug & FF_DEBUG_PICT_INFO)

         av_log(s->avctx, AV_LOG_DEBUG, "profile: %d, level: %d vbv buffer: %d, bitrate:%d\n",

                s->avctx->profile, s->avctx->level, s->avctx->rc_buffer_size, s->bit_rate);

 }
 

 static void mpeg_decode_sequence_display_extension(Mpeg1Context *s1)
 {
     MpegEncContext *s= &s1->mpeg_enc_ctx;
     int color_description, w, h;
 
     skip_bits(&s->gb, 3); /* video format */
     color_description= get_bits1(&s->gb);
     if(color_description){

         s->avctx->color_primaries= get_bits(&s->gb, 8);
         s->avctx->color_trc      = get_bits(&s->gb, 8);
         s->avctx->colorspace     = get_bits(&s->gb, 8);

     }
     w= get_bits(&s->gb, 14);
     skip_bits(&s->gb, 1); //marker
     h= get_bits(&s->gb, 14);

     // remaining 3 bits are zero padding

     s1->pan_scan.width= 16*w;
     s1->pan_scan.height=16*h;

     if(s->avctx->debug & FF_DEBUG_PICT_INFO)

         av_log(s->avctx, AV_LOG_DEBUG, "sde w:%d, h:%d\n", w, h);

 }
 
 static void mpeg_decode_picture_display_extension(Mpeg1Context *s1)
 {
     MpegEncContext *s= &s1->mpeg_enc_ctx;

     int i,nofco;
 
     nofco = 1;
     if(s->progressive_sequence){
         if(s->repeat_first_field){

             nofco++;
             if(s->top_field_first)
                 nofco++;
         }

     }else{
         if(s->picture_structure == PICT_FRAME){
             nofco++;

             if(s->repeat_first_field)
                 nofco++;
         }

     }
     for(i=0; i<nofco; i++){

         s1->pan_scan.position[i][0]= get_sbits(&s->gb, 16);
         skip_bits(&s->gb, 1); //marker
         s1->pan_scan.position[i][1]= get_sbits(&s->gb, 16);
         skip_bits(&s->gb, 1); //marker
     }

     if(s->avctx->debug & FF_DEBUG_PICT_INFO)

         av_log(s->avctx, AV_LOG_DEBUG, "pde (%d,%d) (%d,%d) (%d,%d)\n",
             s1->pan_scan.position[0][0], s1->pan_scan.position[0][1],
             s1->pan_scan.position[1][0], s1->pan_scan.position[1][1],

             s1->pan_scan.position[2][0], s1->pan_scan.position[2][1]
         );
 }
 

 static int load_matrix(MpegEncContext *s, uint16_t matrix0[64], uint16_t matrix1[64], int intra){
     int i;
 
     for(i=0; i<64; i++) {
         int j = s->dsp.idct_permutation[ ff_zigzag_direct[i] ];
         int v = get_bits(&s->gb, 8);
         if(v==0){
             av_log(s->avctx, AV_LOG_ERROR, "matrix damaged\n");
             return -1;
         }

         if(intra && i==0 && v!=8){
             av_log(s->avctx, AV_LOG_ERROR, "intra matrix invalid, ignoring\n");
             v= 8; // needed by pink.mpg / issue1046
         }

         matrix0[j] = v;
         if(matrix1)
             matrix1[j] = v;
     }
     return 0;
 }
 

 static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)
 {

     av_dlog(s->avctx, "matrix extension\n");

     if(get_bits1(&s->gb)) load_matrix(s, s->chroma_intra_matrix, s->intra_matrix, 1);
     if(get_bits1(&s->gb)) load_matrix(s, s->chroma_inter_matrix, s->inter_matrix, 0);
     if(get_bits1(&s->gb)) load_matrix(s, s->chroma_intra_matrix, NULL           , 1);
     if(get_bits1(&s->gb)) load_matrix(s, s->chroma_inter_matrix, NULL           , 0);

 }
 

 static void mpeg_decode_picture_coding_extension(Mpeg1Context *s1)

 {

     MpegEncContext *s= &s1->mpeg_enc_ctx;
 

     s->full_pel[0] = s->full_pel[1] = 0;
     s->mpeg_f_code[0][0] = get_bits(&s->gb, 4);
     s->mpeg_f_code[0][1] = get_bits(&s->gb, 4);
     s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);
     s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);

     if(!s->pict_type && s1->mpeg_enc_ctx_allocated){
         av_log(s->avctx, AV_LOG_ERROR, "Missing picture start code, guessing missing values\n");
         if(s->mpeg_f_code[1][0] == 15 && s->mpeg_f_code[1][1]==15){
             if(s->mpeg_f_code[0][0] == 15 && s->mpeg_f_code[0][1] == 15)

                 s->pict_type= AV_PICTURE_TYPE_I;

             else

                 s->pict_type= AV_PICTURE_TYPE_P;

         }else

             s->pict_type= AV_PICTURE_TYPE_B;

         s->current_picture.pict_type= s->pict_type;

         s->current_picture.key_frame= s->pict_type == AV_PICTURE_TYPE_I;

     }

     s->intra_dc_precision = get_bits(&s->gb, 2);
     s->picture_structure = get_bits(&s->gb, 2);

     s->top_field_first = get_bits1(&s->gb);
     s->frame_pred_frame_dct = get_bits1(&s->gb);
     s->concealment_motion_vectors = get_bits1(&s->gb);
     s->q_scale_type = get_bits1(&s->gb);
     s->intra_vlc_format = get_bits1(&s->gb);
     s->alternate_scan = get_bits1(&s->gb);
     s->repeat_first_field = get_bits1(&s->gb);
     s->chroma_420_type = get_bits1(&s->gb);
     s->progressive_frame = get_bits1(&s->gb);

     if(s->progressive_sequence && !s->progressive_frame){

         s->progressive_frame= 1;

         av_log(s->avctx, AV_LOG_ERROR, "interlaced frame in progressive sequence, ignoring\n");
     }
 
     if(s->picture_structure==0 || (s->progressive_frame && s->picture_structure!=PICT_FRAME)){
         av_log(s->avctx, AV_LOG_ERROR, "picture_structure %d invalid, ignoring\n", s->picture_structure);

         s->picture_structure= PICT_FRAME;

     }
 

     if(s->progressive_sequence && !s->frame_pred_frame_dct){

         av_log(s->avctx, AV_LOG_ERROR, "invalid frame_pred_frame_dct\n");

     }
 

     if(s->picture_structure == PICT_FRAME){

         s->first_field=0;

         s->v_edge_pos= 16*s->mb_height;
     }else{

         s->first_field ^= 1;

         s->v_edge_pos=  8*s->mb_height;

         memset(s->mbskip_table, 0, s->mb_stride*s->mb_height);

     }

     if(s->alternate_scan){

         ff_init_scantable(s->dsp.idct_permutation, &s->inter_scantable  , ff_alternate_vertical_scan);
         ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable  , ff_alternate_vertical_scan);

     }else{

         ff_init_scantable(s->dsp.idct_permutation, &s->inter_scantable  , ff_zigzag_direct);
         ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable  , ff_zigzag_direct);

     }

     /* composite display not parsed */

     av_dlog(s->avctx, "intra_dc_precision=%d\n", s->intra_dc_precision);
     av_dlog(s->avctx, "picture_structure=%d\n", s->picture_structure);
     av_dlog(s->avctx, "top field first=%d\n", s->top_field_first);
     av_dlog(s->avctx, "repeat first field=%d\n", s->repeat_first_field);
     av_dlog(s->avctx, "conceal=%d\n", s->concealment_motion_vectors);
     av_dlog(s->avctx, "intra_vlc_format=%d\n", s->intra_vlc_format);
     av_dlog(s->avctx, "alternate_scan=%d\n", s->alternate_scan);
     av_dlog(s->avctx, "frame_pred_frame_dct=%d\n", s->frame_pred_frame_dct);
     av_dlog(s->avctx, "progressive_frame=%d\n", s->progressive_frame);

 }
 

 static void exchange_uv(MpegEncContext *s){

     DCTELEM (*tmp)[64];
 
     tmp           = s->pblocks[4];

     s->pblocks[4] = s->pblocks[5];
     s->pblocks[5] = tmp;

 }
 

 static int mpeg_field_start(MpegEncContext *s, const uint8_t *buf, int buf_size){

     AVCodecContext *avctx= s->avctx;
     Mpeg1Context *s1 = (Mpeg1Context*)s;

 
     /* start frame decoding */

     if(s->first_field || s->picture_structure==PICT_FRAME){

         if(MPV_frame_start(s, avctx) < 0)

             return -1;

 
         ff_er_frame_start(s);
 

         /* first check if we must repeat the frame */

         s->current_picture_ptr->repeat_pict = 0;

         if (s->repeat_first_field) {
             if (s->progressive_sequence) {
                 if (s->top_field_first)

                     s->current_picture_ptr->repeat_pict = 4;

                 else

                     s->current_picture_ptr->repeat_pict = 2;

             } else if (s->progressive_frame) {

                 s->current_picture_ptr->repeat_pict = 1;

             }

         }

 
         *s->current_picture_ptr->pan_scan= s1->pan_scan;

         if (HAVE_PTHREADS && (avctx->active_thread_type & FF_THREAD_FRAME))

             ff_thread_finish_setup(avctx);

     }else{ //second field

             int i;

             if(!s->current_picture_ptr){

                 av_log(s->avctx, AV_LOG_ERROR, "first field missing\n");

                 return -1;
             }

             for(i=0; i<4; i++){
                 s->current_picture.data[i] = s->current_picture_ptr->data[i];
                 if(s->picture_structure == PICT_BOTTOM_FIELD){
                     s->current_picture.data[i] += s->current_picture_ptr->linesize[i];

                 }

             }

     }

 
     if (avctx->hwaccel) {
         if (avctx->hwaccel->start_frame(avctx, buf, buf_size) < 0)
             return -1;
     }
 

 // MPV_frame_start will call this function too,
 // but we need to call it on every field

     if(CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration)

         if(ff_xvmc_field_start(s,avctx) < 0)

             return -1;

     return 0;
 }
 
 #define DECODE_SLICE_ERROR -1
 #define DECODE_SLICE_OK 0
 
 /**
  * decodes a slice. MpegEncContext.mb_y must be set to the MB row from the startcode
  * @return DECODE_SLICE_ERROR if the slice is damaged<br>
  *         DECODE_SLICE_OK if this slice is ok<br>
  */
 static int mpeg_decode_slice(Mpeg1Context *s1, int mb_y,

                              const uint8_t **buf, int buf_size)

 {
     MpegEncContext *s = &s1->mpeg_enc_ctx;
     AVCodecContext *avctx= s->avctx;
     const int field_pic= s->picture_structure != PICT_FRAME;

     const int lowres= s->avctx->lowres;

 
     s->resync_mb_x=
     s->resync_mb_y= -1;
 

     assert(mb_y < s->mb_height);

     init_get_bits(&s->gb, *buf, buf_size*8);

     ff_mpeg1_clean_buffers(s);
     s->interlaced_dct = 0;
 

     s->qscale = get_qscale(s);

     if(s->qscale == 0){

         av_log(s->avctx, AV_LOG_ERROR, "qscale == 0\n");

         return -1;

     }

     /* extra slice info */

     while (get_bits1(&s->gb) != 0) {
         skip_bits(&s->gb, 8);

     }

     s->mb_x=0;

     if(mb_y==0 && s->codec_tag == AV_RL32("SLIF")){
         skip_bits1(&s->gb);
     }else{

         for(;;) {
             int code = get_vlc2(&s->gb, mbincr_vlc.table, MBINCR_VLC_BITS, 2);
             if (code < 0){
                 av_log(s->avctx, AV_LOG_ERROR, "first mb_incr damaged\n");
                 return -1;
             }
             if (code >= 33) {
                 if (code == 33) {
                     s->mb_x += 33;
                 }
                 /* otherwise, stuffing, nothing to do */
             } else {
                 s->mb_x += code;
                 break;

             }
         }
     }

     if(s->mb_x >= (unsigned)s->mb_width){
         av_log(s->avctx, AV_LOG_ERROR, "initial skip overflow\n");
         return -1;
     }

     if (avctx->hwaccel) {
         const uint8_t *buf_end, *buf_start = *buf - 4; /* include start_code */
         int start_code = -1;
         buf_end = ff_find_start_code(buf_start + 2, *buf + buf_size, &start_code);
         if (buf_end < *buf + buf_size)
             buf_end -= 4;
         s->mb_y = mb_y;
         if (avctx->hwaccel->decode_slice(avctx, buf_start, buf_end - buf_start) < 0)
             return DECODE_SLICE_ERROR;
         *buf = buf_end;
         return DECODE_SLICE_OK;
     }
 

     s->resync_mb_x= s->mb_x;

     s->resync_mb_y= s->mb_y= mb_y;

     s->mb_skip_run= 0;

     ff_init_block_index(s);

     if (s->mb_y==0 && s->mb_x==0 && (s->first_field || s->picture_structure==PICT_FRAME)) {
         if(s->avctx->debug&FF_DEBUG_PICT_INFO){

              av_log(s->avctx, AV_LOG_DEBUG, "qp:%d fc:%2d%2d%2d%2d %s %s %s %s %s dc:%d pstruct:%d fdct:%d cmv:%d qtype:%d ivlc:%d rff:%d %s\n",

                  s->qscale, s->mpeg_f_code[0][0],s->mpeg_f_code[0][1],s->mpeg_f_code[1][0],s->mpeg_f_code[1][1],

                  s->pict_type == AV_PICTURE_TYPE_I ? "I" : (s->pict_type == AV_PICTURE_TYPE_P ? "P" : (s->pict_type == AV_PICTURE_TYPE_B ? "B" : "S")),

                  s->progressive_sequence ? "ps" :"", s->progressive_frame ? "pf" : "", s->alternate_scan ? "alt" :"", s->top_field_first ? "top" :"",

                  s->intra_dc_precision, s->picture_structure, s->frame_pred_frame_dct, s->concealment_motion_vectors,
                  s->q_scale_type, s->intra_vlc_format, s->repeat_first_field, s->chroma_420_type ? "420" :"");
         }

     }
 

     for(;;) {

         //If 1, we memcpy blocks in xvmcvideo.

         if(CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration > 1)

             ff_xvmc_init_block(s);//set s->block

         if(mpeg_decode_mb(s, s->block) < 0)

             return -1;

         if(s->current_picture.motion_val[0] && !s->encoding){ //note motion_val is normally NULL unless we want to extract the MVs

             const int wrap = s->b8_stride;

             int xy = s->mb_x*2 + s->mb_y*2*wrap;

             int b8_xy= 4*(s->mb_x + s->mb_y*s->mb_stride);

             int motion_x, motion_y, dir, i;

             for(i=0; i<2; i++){
                 for(dir=0; dir<2; dir++){

                     if (s->mb_intra || (dir==1 && s->pict_type != AV_PICTURE_TYPE_B)) {

                         motion_x = motion_y = 0;

                     }else if (s->mv_type == MV_TYPE_16X16 || (s->mv_type == MV_TYPE_FIELD && field_pic)){

                         motion_x = s->mv[dir][0][0];
                         motion_y = s->mv[dir][0][1];
                     } else /*if ((s->mv_type == MV_TYPE_FIELD) || (s->mv_type == MV_TYPE_16X8))*/ {
                         motion_x = s->mv[dir][i][0];
                         motion_y = s->mv[dir][i][1];
                     }

                     s->current_picture.motion_val[dir][xy    ][0] = motion_x;
                     s->current_picture.motion_val[dir][xy    ][1] = motion_y;
                     s->current_picture.motion_val[dir][xy + 1][0] = motion_x;
                     s->current_picture.motion_val[dir][xy + 1][1] = motion_y;

                     s->current_picture.ref_index [dir][b8_xy    ]=
                     s->current_picture.ref_index [dir][b8_xy + 1]= s->field_select[dir][i];

                     assert(s->field_select[dir][i]==0 || s->field_select[dir][i]==1);

                 }

                 xy += wrap;

                 b8_xy +=2;

             }
         }

         s->dest[0] += 16 >> lowres;

         s->dest[1] +=(16 >> lowres) >> s->chroma_x_shift;
         s->dest[2] +=(16 >> lowres) >> s->chroma_x_shift;

         MPV_decode_mb(s, s->block);

         if (++s->mb_x >= s->mb_width) {

             const int mb_size= 16>>s->avctx->lowres;

             ff_draw_horiz_band(s, mb_size*(s->mb_y>>field_pic), mb_size);

             MPV_report_decode_progress(s);

 
             s->mb_x = 0;

             s->mb_y += 1<<field_pic;

             if(s->mb_y >= s->mb_height){

                 int left= get_bits_left(&s->gb);

                 int is_d10= s->chroma_format==2 && s->pict_type==AV_PICTURE_TYPE_I && avctx->profile==0 && avctx->level==5

                             && s->intra_dc_precision == 2 && s->q_scale_type == 1 && s->alternate_scan == 0
                             && s->progressive_frame == 0 /* vbv_delay == 0xBBB || 0xE10*/;

                 if(left < 0 || (left && show_bits(&s->gb, FFMIN(left, 23)) && !is_d10)

                    || (avctx->error_recognition >= FF_ER_AGGRESSIVE && left>8)){

                     av_log(avctx, AV_LOG_ERROR, "end mismatch left=%d %0X\n", left, show_bits(&s->gb, FFMIN(left, 23)));

                     return -1;
                 }else
                     goto eos;
             }

             ff_init_block_index(s);

         }
 
         /* skip mb handling */

         if (s->mb_skip_run == -1) {

             /* read increment again */

             s->mb_skip_run = 0;

             for(;;) {
                 int code = get_vlc2(&s->gb, mbincr_vlc.table, MBINCR_VLC_BITS, 2);

                 if (code < 0){

                     av_log(s->avctx, AV_LOG_ERROR, "mb incr damaged\n");

                     return -1;

                 }

                 if (code >= 33) {
                     if (code == 33) {

                         s->mb_skip_run += 33;

                     }else if(code == 35){
                         if(s->mb_skip_run != 0 || show_bits(&s->gb, 15) != 0){

                             av_log(s->avctx, AV_LOG_ERROR, "slice mismatch\n");

                             return -1;
                         }
                         goto eos; /* end of slice */

                     }
                     /* otherwise, stuffing, nothing to do */
                 } else {

                     s->mb_skip_run += code;

                     break;
                 }
             }

             if(s->mb_skip_run){
                 int i;

                 if(s->pict_type == AV_PICTURE_TYPE_I){

                     av_log(s->avctx, AV_LOG_ERROR, "skipped MB in I frame at %d %d\n", s->mb_x, s->mb_y);
                     return -1;
                 }
 
                 /* skip mb */
                 s->mb_intra = 0;
                 for(i=0;i<12;i++)
                     s->block_last_index[i] = -1;
                 if(s->picture_structure == PICT_FRAME)
                     s->mv_type = MV_TYPE_16X16;
                 else
                     s->mv_type = MV_TYPE_FIELD;

                 if (s->pict_type == AV_PICTURE_TYPE_P) {

                     /* if P type, zero motion vector is implied */
                     s->mv_dir = MV_DIR_FORWARD;
                     s->mv[0][0][0] = s->mv[0][0][1] = 0;
                     s->last_mv[0][0][0] = s->last_mv[0][0][1] = 0;
                     s->last_mv[0][1][0] = s->last_mv[0][1][1] = 0;

                     s->field_select[0][0]= (s->picture_structure - 1) & 1;

                 } else {
                     /* if B type, reuse previous vectors and directions */
                     s->mv[0][0][0] = s->last_mv[0][0][0];
                     s->mv[0][0][1] = s->last_mv[0][0][1];
                     s->mv[1][0][0] = s->last_mv[1][0][0];
                     s->mv[1][0][1] = s->last_mv[1][0][1];
                 }
             }

         }

     }

 eos: // end of slice

     *buf += (get_bits_count(&s->gb)-1)/8;

 //printf("y %d %d %d %d\n", s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y);

     return 0;
 }

 static int slice_decode_thread(AVCodecContext *c, void *arg){

     MpegEncContext *s= *(void**)arg;

     const uint8_t *buf= s->gb.buffer;

     int mb_y= s->start_mb_y;

     const int field_pic= s->picture_structure != PICT_FRAME;

     s->error_count= (3*(s->end_mb_y - s->start_mb_y)*s->mb_width) >> field_pic;

 
     for(;;){

         uint32_t start_code;
         int ret;

 
         ret= mpeg_decode_slice((Mpeg1Context*)s, mb_y, &buf, s->gb.buffer_end - buf);
         emms_c();

 //av_log(c, AV_LOG_DEBUG, "ret:%d resync:%d/%d mb:%d/%d ts:%d/%d ec:%d\n",

 //ret, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, s->start_mb_y, s->end_mb_y, s->error_count);
         if(ret < 0){
             if(s->resync_mb_x>=0 && s->resync_mb_y>=0)
                 ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x, s->mb_y, AC_ERROR|DC_ERROR|MV_ERROR);
         }else{
             ff_er_add_slice(s, s->resync_mb_x, s->resync_mb_y, s->mb_x-1, s->mb_y, AC_END|DC_END|MV_END);
         }

         if(s->mb_y == s->end_mb_y)
             return 0;

         start_code= -1;
         buf = ff_find_start_code(buf, s->gb.buffer_end, &start_code);

         mb_y= (start_code - SLICE_MIN_START_CODE) << field_pic;
         if (s->picture_structure == PICT_BOTTOM_FIELD)
             mb_y++;

         if(mb_y < 0 || mb_y >= s->end_mb_y)
             return -1;
     }

     return 0; //not reached
 }
 

 /**

  * Handle slice ends.

  * @return 1 if it seems to be the last slice

  */
 static int slice_end(AVCodecContext *avctx, AVFrame *pict)
 {
     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;

     if (!s1->mpeg_enc_ctx_allocated || !s->current_picture_ptr)

         return 0;
 

     if (s->avctx->hwaccel) {
         if (s->avctx->hwaccel->end_frame(s->avctx) < 0)
             av_log(avctx, AV_LOG_ERROR, "hardware accelerator failed to decode picture\n");
     }
 

     if(CONFIG_MPEG_XVMC_DECODER && s->avctx->xvmc_acceleration)

         ff_xvmc_field_end(s);

     /* end of slice reached */

     if (/*s->mb_y<<field_pic == s->mb_height &&*/ !s->first_field) {

         /* end of image */

         s->current_picture_ptr->qscale_type= FF_QSCALE_TYPE_MPEG2;

         ff_er_frame_end(s);

 
         MPV_frame_end(s);
 

         if (s->pict_type == AV_PICTURE_TYPE_B || s->low_delay) {

             *pict= *(AVFrame*)s->current_picture_ptr;

             ff_print_debug_info(s, pict);

         } else {

             if (avctx->active_thread_type & FF_THREAD_FRAME)

                 s->picture_number++;

             /* latency of 1 frame for I- and P-frames */

             /* XXX: use another variable than picture_number */

             if (s->last_picture_ptr != NULL) {

                 *pict= *(AVFrame*)s->last_picture_ptr;

                  ff_print_debug_info(s, pict);

             }
         }

 
         return 1;
     } else {
         return 0;

     }
 }
 

 static int mpeg1_decode_sequence(AVCodecContext *avctx,

                                  const uint8_t *buf, int buf_size)

 {
     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;

     int width,height;

     int i, v, j;

     init_get_bits(&s->gb, buf, buf_size*8);

     width = get_bits(&s->gb, 12);
     height = get_bits(&s->gb, 12);

     if (width <= 0 || height <= 0)

         return -1;

     s->aspect_ratio_info= get_bits(&s->gb, 4);

     if (s->aspect_ratio_info == 0) {
         av_log(avctx, AV_LOG_ERROR, "aspect ratio has forbidden 0 value\n");

         if (avctx->error_recognition >= FF_ER_COMPLIANT)

             return -1;
     }

     s->frame_rate_index = get_bits(&s->gb, 4);

     if (s->frame_rate_index == 0 || s->frame_rate_index > 13)

         return -1;
     s->bit_rate = get_bits(&s->gb, 18) * 400;

     if (get_bits1(&s->gb) == 0) /* marker */

         return -1;

     s->width = width;
     s->height = height;

     s->avctx->rc_buffer_size= get_bits(&s->gb, 10) * 1024*16;

     skip_bits(&s->gb, 1);

 
     /* get matrix */

     if (get_bits1(&s->gb)) {

         load_matrix(s, s->chroma_intra_matrix, s->intra_matrix, 1);

     } else {
         for(i=0;i<64;i++) {

             j = s->dsp.idct_permutation[i];

             v = ff_mpeg1_default_intra_matrix[i];

             s->intra_matrix[j] = v;
             s->chroma_intra_matrix[j] = v;

         }
     }

     if (get_bits1(&s->gb)) {

         load_matrix(s, s->chroma_inter_matrix, s->inter_matrix, 0);

     } else {
         for(i=0;i<64;i++) {

             int j= s->dsp.idct_permutation[i];

             v = ff_mpeg1_default_non_intra_matrix[i];

             s->inter_matrix[j] = v;
             s->chroma_inter_matrix[j] = v;

         }
     }

     if(show_bits(&s->gb, 23) != 0){
         av_log(s->avctx, AV_LOG_ERROR, "sequence header damaged\n");
         return -1;
     }

     /* we set MPEG-2 parameters so that it emulates MPEG-1 */

     s->progressive_sequence = 1;
     s->progressive_frame = 1;
     s->picture_structure = PICT_FRAME;
     s->frame_pred_frame_dct = 1;

     s->chroma_format = 1;

     s->codec_id= s->avctx->codec_id= CODEC_ID_MPEG1VIDEO;

     avctx->sub_id = 1; /* indicates MPEG-1 */

     s->out_format = FMT_MPEG1;

     s->swap_uv = 0;//AFAIK VCR2 does not have SEQ_HEADER

     if(s->flags & CODEC_FLAG_LOW_DELAY) s->low_delay=1;

     if(s->avctx->debug & FF_DEBUG_PICT_INFO)

         av_log(s->avctx, AV_LOG_DEBUG, "vbv buffer: %d, bitrate:%d\n",

                s->avctx->rc_buffer_size, s->bit_rate);

     return 0;
 }
 

 static int vcr2_init_sequence(AVCodecContext *avctx)
 {
     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;

     int i, v;

     /* start new MPEG-1 context decoding */

     s->out_format = FMT_MPEG1;
     if (s1->mpeg_enc_ctx_allocated) {
         MPV_common_end(s);
     }

     s->width  = avctx->coded_width;
     s->height = avctx->coded_height;

     avctx->has_b_frames= 0; //true?

     s->low_delay= 1;

     avctx->pix_fmt = mpeg_get_pixelformat(avctx);

     avctx->hwaccel = ff_find_hwaccel(avctx->codec->id, avctx->pix_fmt);

     if( avctx->pix_fmt == PIX_FMT_XVMC_MPEG2_IDCT || avctx->hwaccel )

         if( avctx->idct_algo == FF_IDCT_AUTO )
             avctx->idct_algo = FF_IDCT_SIMPLE;

     if (MPV_common_init(s) < 0)
         return -1;

     exchange_uv(s);//common init reset pblocks, so we swap them here

     s->swap_uv = 1;// in case of xvmc we need to swap uv for each MB

     s1->mpeg_enc_ctx_allocated = 1;
 
     for(i=0;i<64;i++) {
         int j= s->dsp.idct_permutation[i];
         v = ff_mpeg1_default_intra_matrix[i];
         s->intra_matrix[j] = v;
         s->chroma_intra_matrix[j] = v;
 
         v = ff_mpeg1_default_non_intra_matrix[i];
         s->inter_matrix[j] = v;
         s->chroma_inter_matrix[j] = v;
     }
 
     s->progressive_sequence = 1;
     s->progressive_frame = 1;
     s->picture_structure = PICT_FRAME;
     s->frame_pred_frame_dct = 1;

     s->chroma_format = 1;

     s->codec_id= s->avctx->codec_id= CODEC_ID_MPEG2VIDEO;

     avctx->sub_id = 2; /* indicates MPEG-2 */

     s1->save_width           = s->width;
     s1->save_height          = s->height;
     s1->save_progressive_seq = s->progressive_sequence;

     return 0;
 }
 
 

 static void mpeg_decode_user_data(AVCodecContext *avctx,

                                   const uint8_t *p, int buf_size)

 {

     const uint8_t *buf_end = p+buf_size;

 
     /* we parse the DTG active format information */

     if (buf_end - p >= 5 &&

         p[0] == 'D' && p[1] == 'T' && p[2] == 'G' && p[3] == '1') {

         int flags = p[4];

         p += 5;
         if (flags & 0x80) {
             /* skip event id */
             p += 2;
         }
         if (flags & 0x40) {

             if (buf_end - p < 1)

                 return;
             avctx->dtg_active_format = p[0] & 0x0f;
         }
     }
 }
 

 static void mpeg_decode_gop(AVCodecContext *avctx,

                             const uint8_t *buf, int buf_size){
     Mpeg1Context *s1 = avctx->priv_data;
     MpegEncContext *s = &s1->mpeg_enc_ctx;
 
     int time_code_hours, time_code_minutes;
     int time_code_seconds, time_code_pictures;

     int broken_link;

 
     init_get_bits(&s->gb, buf, buf_size*8);
 

     skip_bits1(&s->gb); /* drop_frame_flag */

     time_code_hours=get_bits(&s->gb,5);
     time_code_minutes = get_bits(&s->gb,6);
     skip_bits1(&s->gb);//marker bit
     time_code_seconds = get_bits(&s->gb,6);
     time_code_pictures = get_bits(&s->gb,6);
 

     s->closed_gop = get_bits1(&s->gb);

     /*broken_link indicate that after editing the
       reference frames of the first B-Frames after GOP I-Frame
       are missing (open gop)*/
     broken_link = get_bits1(&s->gb);
 
     if(s->avctx->debug & FF_DEBUG_PICT_INFO)

         av_log(s->avctx, AV_LOG_DEBUG, "GOP (%2d:%02d:%02d.[%02d]) closed_gop=%d broken_link=%d\n",

             time_code_hours, time_code_minutes, time_code_seconds,

             time_code_pictures, s->closed_gop, broken_link);

 }

 /**

  * Find the end of the current frame in the bitstream.

  * @return the position of the first byte of the next frame, or -1
  */

 int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)

 {

     int i;

     uint32_t state= pc->state;

     /* EOF considered as end of frame */
     if (buf_size == 0)
         return 0;
 
 /*
  0  frame start         -> 1/4
  1  first_SEQEXT        -> 0/2
  2  first field start   -> 3/0
  3  second_SEQEXT       -> 2/0
  4  searching end
 */
 
     for(i=0; i<buf_size; i++){
         assert(pc->frame_start_found>=0 && pc->frame_start_found<=4);
         if(pc->frame_start_found&1){
             if(state == EXT_START_CODE && (buf[i]&0xF0) != 0x80)
                 pc->frame_start_found--;
             else if(state == EXT_START_CODE+2){
                 if((buf[i]&3) == 3) pc->frame_start_found= 0;
                 else                pc->frame_start_found= (pc->frame_start_found+1)&3;
             }
             state++;
         }else{

             i= ff_find_start_code(buf+i, buf+buf_size, &state) - buf - 1;

             if(pc->frame_start_found==0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE){

                 i++;

                 pc->frame_start_found=4;

             }

             if(state == SEQ_END_CODE){
                 pc->state=-1;
                 return i+1;
             }

             if(pc->frame_start_found==2 && state == SEQ_START_CODE)
                 pc->frame_start_found= 0;
             if(pc->frame_start_found<4 && state == EXT_START_CODE)
                 pc->frame_start_found++;
             if(pc->frame_start_found == 4 && (state&0xFFFFFF00) == 0x100){

                 if(state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE){
                     pc->frame_start_found=0;

                     pc->state=-1;

                     return i-3;
                 }
             }

             if(pc->frame_start_found == 0 && s && state == PICTURE_START_CODE){

                 ff_fetch_timestamp(s, i-3, 1);

             }

         }

     }

     pc->state= state;

     return END_NOT_FOUND;

 }
 

 static int decode_chunks(AVCodecContext *avctx,
                              AVFrame *picture, int *data_size,
                              const uint8_t *buf, int buf_size);
 

 /* handle buffering and image synchronisation */

 static int mpeg_decode_frame(AVCodecContext *avctx,

                              void *data, int *data_size,

                              AVPacket *avpkt)

 {

     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

     Mpeg1Context *s = avctx->priv_data;

     AVFrame *picture = data;

     MpegEncContext *s2 = &s->mpeg_enc_ctx;

     av_dlog(avctx, "fill_buffer\n");

     if (buf_size == 0 || (buf_size == 4 && AV_RB32(buf) == SEQ_END_CODE)) {

         /* special case for last picture */
         if (s2->low_delay==0 && s2->next_picture_ptr) {
             *picture= *(AVFrame*)s2->next_picture_ptr;
             s2->next_picture_ptr= NULL;

             *data_size = sizeof(AVFrame);
         }

         return buf_size;

     }
 

     if(s2->flags&CODEC_FLAG_TRUNCATED){

         int next= ff_mpeg1_find_frame_end(&s2->parse_context, buf, buf_size, NULL);

         if( ff_combine_frame(&s2->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )

             return buf_size;

     }
 
 #if 0
     if (s->repeat_field % 2 == 1) {

         s->repeat_field++;
         //fprintf(stderr,"\nRepeating last frame: %d -> %d! pict: %d %d", avctx->frame_number-1, avctx->frame_number,

         //        s2->picture_number, s->repeat_field);
         if (avctx->flags & CODEC_FLAG_REPEAT_FIELD) {
             *data_size = sizeof(AVPicture);
             goto the_end;
         }

     }

 #endif

     if(s->mpeg_enc_ctx_allocated==0 && avctx->codec_tag == AV_RL32("VCR2"))

         vcr2_init_sequence(avctx);

     s->slice_count= 0;

     if(avctx->extradata && !avctx->frame_number)
         decode_chunks(avctx, picture, data_size, avctx->extradata, avctx->extradata_size);
 

     return decode_chunks(avctx, picture, data_size, buf, buf_size);
 }
 
 static int decode_chunks(AVCodecContext *avctx,
                              AVFrame *picture, int *data_size,
                              const uint8_t *buf, int buf_size)
 {
     Mpeg1Context *s = avctx->priv_data;
     MpegEncContext *s2 = &s->mpeg_enc_ctx;
     const uint8_t *buf_ptr = buf;
     const uint8_t *buf_end = buf + buf_size;
     int ret, input_size;

     int last_code= 0;

     for(;;) {

         /* find next start code */

         uint32_t start_code = -1;

         buf_ptr = ff_find_start_code(buf_ptr,buf_end, &start_code);

         if (start_code > 0x1ff){

             if(s2->pict_type != AV_PICTURE_TYPE_B || avctx->skip_frame <= AVDISCARD_DEFAULT){

                 if(HAVE_THREADS && (avctx->active_thread_type & FF_THREAD_SLICE)){

                     int i;

                     av_assert0(avctx->thread_count > 1);

                     avctx->execute(avctx, slice_decode_thread,  &s2->thread_context[0], NULL, s->slice_count, sizeof(void*));

                     for(i=0; i<s->slice_count; i++)
                         s2->error_count += s2->thread_context[i]->error_count;
                 }

                 if (CONFIG_VDPAU && uses_vdpau(avctx))

                     ff_vdpau_mpeg_picture_complete(s2, buf, buf_size, s->slice_count);
 

                 if (slice_end(avctx, picture)) {
                     if(s2->last_picture_ptr || s2->low_delay) //FIXME merge with the stuff in mpeg_decode_slice
                         *data_size = sizeof(AVPicture);
                 }

             }

             s2->pict_type= 0;

             return FFMAX(0, buf_ptr - buf - s2->parse_context.last_index);

         }

         input_size = buf_end - buf_ptr;
 
         if(avctx->debug & FF_DEBUG_STARTCODE){

             av_log(avctx, AV_LOG_DEBUG, "%3X at %td left %d\n", start_code, buf_ptr-buf, input_size);

         }

         /* prepare data for next start code */
         switch(start_code) {
         case SEQ_START_CODE:

             if(last_code == 0){

             mpeg1_decode_sequence(avctx, buf_ptr,
                                     input_size);

                 s->sync=1;

             }else{
                 av_log(avctx, AV_LOG_ERROR, "ignoring SEQ_START_CODE after %X\n", last_code);
             }

             break;

         case PICTURE_START_CODE:

             if (HAVE_THREADS && (avctx->active_thread_type&FF_THREAD_SLICE) && s->slice_count) {

                 int i;
 
                 avctx->execute(avctx, slice_decode_thread,
                                s2->thread_context, NULL,
                                s->slice_count, sizeof(void*));
                 for (i = 0; i < s->slice_count; i++)
                     s2->error_count += s2->thread_context[i]->error_count;
                 s->slice_count = 0;
             }

             if(last_code == 0 || last_code == SLICE_MIN_START_CODE){

             if(mpeg_decode_postinit(avctx) < 0){
                 av_log(avctx, AV_LOG_ERROR, "mpeg_decode_postinit() failure\n");
                 return -1;
             }
 

             /* we have a complete image: we try to decompress it */

             if(mpeg1_decode_picture(avctx,
                                     buf_ptr, input_size) < 0)
                 s2->pict_type=0;

                 s2->first_slice = 1;

             last_code= PICTURE_START_CODE;

             }else{
                 av_log(avctx, AV_LOG_ERROR, "ignoring pic after %X\n", last_code);
             }

             break;
         case EXT_START_CODE:

             init_get_bits(&s2->gb, buf_ptr, input_size*8);
 
             switch(get_bits(&s2->gb, 4)) {
             case 0x1:

                 if(last_code == 0){

                 mpeg_decode_sequence_extension(s);

                 }else{
                     av_log(avctx, AV_LOG_ERROR, "ignoring seq ext after %X\n", last_code);
                 }

                 break;
             case 0x2:
                 mpeg_decode_sequence_display_extension(s);
                 break;
             case 0x3:
                 mpeg_decode_quant_matrix_extension(s2);
                 break;
             case 0x7:
                 mpeg_decode_picture_display_extension(s);
                 break;
             case 0x8:

                 if(last_code == PICTURE_START_CODE){

                 mpeg_decode_picture_coding_extension(s);

                 }else{
                     av_log(avctx, AV_LOG_ERROR, "ignoring pic cod ext after %X\n", last_code);
                 }

                 break;
             }

             break;
         case USER_START_CODE:
             mpeg_decode_user_data(avctx,
                                     buf_ptr, input_size);
             break;
         case GOP_START_CODE:

             if(last_code == 0){

             s2->first_field=0;
             mpeg_decode_gop(avctx,
                                     buf_ptr, input_size);

                 s->sync=1;

             }else{
                 av_log(avctx, AV_LOG_ERROR, "ignoring GOP_START_CODE after %X\n", last_code);
             }

             break;
         default:
             if (start_code >= SLICE_MIN_START_CODE &&

                 start_code <= SLICE_MAX_START_CODE && last_code!=0) {

                 const int field_pic= s2->picture_structure != PICT_FRAME;
                 int mb_y= (start_code - SLICE_MIN_START_CODE) << field_pic;

                 last_code= SLICE_MIN_START_CODE;

                 if(s2->picture_structure == PICT_BOTTOM_FIELD)
                     mb_y++;
 

                 if (mb_y >= s2->mb_height){
                     av_log(s2->avctx, AV_LOG_ERROR, "slice below image (%d >= %d)\n", mb_y, s2->mb_height);
                     return -1;
                 }
 

                 if(s2->last_picture_ptr==NULL){

                 /* Skip B-frames if we do not have reference frames and gop is not closed */

                     if(s2->pict_type==AV_PICTURE_TYPE_B){

                         if(!s2->closed_gop)
                             break;
                     }

                 }

                 if(s2->pict_type==AV_PICTURE_TYPE_I)

                     s->sync=1;

                 if(s2->next_picture_ptr==NULL){

                 /* Skip P-frames if we do not have a reference frame or we have an invalid header. */

                     if(s2->pict_type==AV_PICTURE_TYPE_P && !s->sync) break;

                 }

                 if(  (avctx->skip_frame >= AVDISCARD_NONREF && s2->pict_type==AV_PICTURE_TYPE_B)
                     ||(avctx->skip_frame >= AVDISCARD_NONKEY && s2->pict_type!=AV_PICTURE_TYPE_I)

                     || avctx->skip_frame >= AVDISCARD_ALL)

                     break;

                 if (!s->mpeg_enc_ctx_allocated) break;
 
                 if(s2->codec_id == CODEC_ID_MPEG2VIDEO){
                     if(mb_y < avctx->skip_top || mb_y >= s2->mb_height - avctx->skip_bottom)
                         break;
                 }

                 if(!s2->pict_type){
                     av_log(avctx, AV_LOG_ERROR, "Missing picture start code\n");
                     break;
                 }
 

                 if(s2->first_slice){
                     s2->first_slice=0;

                     if(mpeg_field_start(s2, buf, buf_size) < 0)

                         return -1;

                 }

                 if(!s2->current_picture_ptr){

                     av_log(avctx, AV_LOG_ERROR, "current_picture not initialized\n");

                     return -1;
                 }

                 if (uses_vdpau(avctx)) {

                     s->slice_count++;
                     break;
                 }
 

                 if(HAVE_THREADS && (avctx->active_thread_type & FF_THREAD_SLICE)){

                     int threshold= (s2->mb_height*s->slice_count + avctx->thread_count/2) / avctx->thread_count;

                     av_assert0(avctx->thread_count > 1);

                     if(threshold <= mb_y){
                         MpegEncContext *thread_context= s2->thread_context[s->slice_count];
 
                         thread_context->start_mb_y= mb_y;
                         thread_context->end_mb_y  = s2->mb_height;
                         if(s->slice_count){
                             s2->thread_context[s->slice_count-1]->end_mb_y= mb_y;
                             ff_update_duplicate_context(thread_context, s2);

                         }

                         init_get_bits(&thread_context->gb, buf_ptr, input_size*8);
                         s->slice_count++;
                     }

                     buf_ptr += 2; //FIXME add minimum number of bytes per slice

                 }else{
                     ret = mpeg_decode_slice(s, mb_y, &buf_ptr, input_size);
                     emms_c();
 
                     if(ret < 0){
                         if(s2->resync_mb_x>=0 && s2->resync_mb_y>=0)
                             ff_er_add_slice(s2, s2->resync_mb_x, s2->resync_mb_y, s2->mb_x, s2->mb_y, AC_ERROR|DC_ERROR|MV_ERROR);
                     }else{
                         ff_er_add_slice(s2, s2->resync_mb_x, s2->resync_mb_y, s2->mb_x-1, s2->mb_y, AC_END|DC_END|MV_END);

                     }
                 }

             }
             break;
         }

     }
 }
 

 static void flush(AVCodecContext *avctx){
     Mpeg1Context *s = avctx->priv_data;
 
     s->sync=0;
 
     ff_mpeg_flush(avctx);
 }
 

 static int mpeg_decode_end(AVCodecContext *avctx)
 {
     Mpeg1Context *s = avctx->priv_data;
 
     if (s->mpeg_enc_ctx_allocated)
         MPV_common_end(&s->mpeg_enc_ctx);
     return 0;
 }
 

 static const AVProfile mpeg2_video_profiles[] = {
     { FF_PROFILE_MPEG2_422,          "4:2:2"              },
     { FF_PROFILE_MPEG2_HIGH,         "High"               },
     { FF_PROFILE_MPEG2_SS,           "Spatially Scalable" },
     { FF_PROFILE_MPEG2_SNR_SCALABLE, "SNR Scalable"       },
     { FF_PROFILE_MPEG2_MAIN,         "Main"               },
     { FF_PROFILE_MPEG2_SIMPLE,       "Simple"             },
     { FF_PROFILE_RESERVED,           "Reserved"           },
     { FF_PROFILE_RESERVED,           "Reserved"           },

     { FF_PROFILE_UNKNOWN },

 };
 
 

 AVCodec ff_mpeg1video_decoder = {

     "mpeg1video",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_MPEG1VIDEO,
     sizeof(Mpeg1Context),
     mpeg_decode_init,
     NULL,
     mpeg_decode_end,
     mpeg_decode_frame,

     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY,

     .flush= flush,

     .max_lowres= 3,

     .long_name= NULL_IF_CONFIG_SMALL("MPEG-1 video"),

     .update_thread_context= ONLY_IF_THREADS_ENABLED(mpeg_decode_update_thread_context)

 };
 

 AVCodec ff_mpeg2video_decoder = {

     "mpeg2video",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_MPEG2VIDEO,
     sizeof(Mpeg1Context),
     mpeg_decode_init,
     NULL,
     mpeg_decode_end,
     mpeg_decode_frame,

     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY | CODEC_CAP_SLICE_THREADS,

     .flush= flush,

     .max_lowres= 3,

     .long_name= NULL_IF_CONFIG_SMALL("MPEG-2 video"),

     .profiles = NULL_IF_CONFIG_SMALL(mpeg2_video_profiles),

 };
 
 //legacy decoder

 AVCodec ff_mpegvideo_decoder = {

     "mpegvideo",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_MPEG2VIDEO,
     sizeof(Mpeg1Context),
     mpeg_decode_init,
     NULL,
     mpeg_decode_end,
     mpeg_decode_frame,

     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_DELAY | CODEC_CAP_SLICE_THREADS,

     .flush= flush,

     .max_lowres= 3,

     .long_name= NULL_IF_CONFIG_SMALL("MPEG-1 video"),

 };

 #if CONFIG_MPEG_XVMC_DECODER

 static av_cold int mpeg_mc_decode_init(AVCodecContext *avctx){

     if( avctx->active_thread_type & FF_THREAD_SLICE )

         return -1;

     if( !(avctx->slice_flags & SLICE_FLAG_CODED_ORDER) )
         return -1;

     if( !(avctx->slice_flags & SLICE_FLAG_ALLOW_FIELD) ){

         av_dlog(avctx, "mpeg12.c: XvMC decoder will work better if SLICE_FLAG_ALLOW_FIELD is set\n");

     }

     mpeg_decode_init(avctx);
 
     avctx->pix_fmt = PIX_FMT_XVMC_MPEG2_IDCT;

     avctx->xvmc_acceleration = 2;//2 - the blocks are packed!

 
     return 0;
 }
 

 AVCodec ff_mpeg_xvmc_decoder = {

     "mpegvideo_xvmc",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_MPEG2VIDEO_XVMC,
     sizeof(Mpeg1Context),
     mpeg_mc_decode_init,
     NULL,
     mpeg_decode_end,
     mpeg_decode_frame,

     CODEC_CAP_DRAW_HORIZ_BAND | CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED| CODEC_CAP_HWACCEL | CODEC_CAP_DELAY,

     .flush= flush,

     .long_name = NULL_IF_CONFIG_SMALL("MPEG-1/2 video XvMC (X-Video Motion Compensation)"),

 };
 
 #endif

 
 #if CONFIG_MPEG_VDPAU_DECODER

 AVCodec ff_mpeg_vdpau_decoder = {

     "mpegvideo_vdpau",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_MPEG2VIDEO,
     sizeof(Mpeg1Context),
     mpeg_decode_init,
     NULL,
     mpeg_decode_end,
     mpeg_decode_frame,
     CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_HWACCEL_VDPAU | CODEC_CAP_DELAY,

     .flush= flush,

     .long_name = NULL_IF_CONFIG_SMALL("MPEG-1/2 video (VDPAU acceleration)"),
 };
 #endif
 

 #if CONFIG_MPEG1_VDPAU_DECODER

 AVCodec ff_mpeg1_vdpau_decoder = {

     "mpeg1video_vdpau",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_MPEG1VIDEO,
     sizeof(Mpeg1Context),
     mpeg_decode_init,
     NULL,
     mpeg_decode_end,
     mpeg_decode_frame,
     CODEC_CAP_DR1 | CODEC_CAP_TRUNCATED | CODEC_CAP_HWACCEL_VDPAU | CODEC_CAP_DELAY,

     .flush= flush,

     .long_name = NULL_IF_CONFIG_SMALL("MPEG-1 video (VDPAU acceleration)"),
 };
 #endif