/*
  * H.26L/H.264/AVC/JVT/14496-10/... parser
  * Copyright (c) 2003 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

  * H.264 / AVC / MPEG4 part10 parser.
  * @author Michael Niedermayer <michaelni@gmx.at>
  */
 

 #define UNCHECKED_BITSTREAM_READER 1
 

 #include "libavutil/attributes.h"

 #include "parser.h"

 #include "h264data.h"
 #include "golomb.h"

 #include "internal.h"

 static int h264_find_frame_end(H264Context *h, const uint8_t *buf,
                                int buf_size)

 {

     int i, j;

     uint32_t state;

     ParseContext *pc = &h->parse_context;

     int next_avc= h->is_avc ? 0 : buf_size;
 

 //    mb_addr= pc->mb_addr - 1;

     state = pc->state;
     if (state > 13)
         state = 7;

     if (h->is_avc && !h->nal_length_size)

         av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");

     for (i = 0; i < buf_size; i++) {

         if (i >= next_avc) {

             int nalsize = 0;
             i = next_avc;

             for (j = 0; j < h->nal_length_size; j++)

                 nalsize = (nalsize << 8) | buf[i++];

             if (nalsize <= 0 || nalsize > buf_size - i) {

                 av_log(h->avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);

                 return buf_size;
             }

             next_avc = i + nalsize;
             state    = 5;

         }
 

         if (state == 7) {

             i += h->h264dsp.h264_find_start_code_candidate(buf + i, next_avc - i);
             if (i < next_avc)

                 state = 2;

         } else if (state <= 2) {
             if (buf[i] == 1)
                 state ^= 5;            // 2->7, 1->4, 0->5
             else if (buf[i])
                 state = 7;
             else
                 state >>= 1;           // 2->1, 1->0, 0->0
         } else if (state <= 5) {

             int nalu_type = buf[i] & 0x1F;
             if (nalu_type == NAL_SEI || nalu_type == NAL_SPS ||
                 nalu_type == NAL_PPS || nalu_type == NAL_AUD) {

                 if (pc->frame_start_found) {

                     i++;

                     goto found;

                 }

             } else if (nalu_type == NAL_SLICE || nalu_type == NAL_DPA ||
                        nalu_type == NAL_IDR_SLICE) {

                 state += 8;

                 continue;
             }

             state = 7;
         } else {

             h->parse_history[h->parse_history_count++]= buf[i];

             if (h->parse_history_count>3) {

                 unsigned int mb, last_mb= h->parse_last_mb;
                 GetBitContext gb;
 
                 init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);
                 h->parse_history_count=0;
                 mb= get_ue_golomb_long(&gb);
                 last_mb= h->parse_last_mb;
                 h->parse_last_mb= mb;

                 if (pc->frame_start_found) {

                     if (mb <= last_mb)

                         goto found;

                 } else

                     pc->frame_start_found = 1;

                 state = 7;

             }
         }
     }

     pc->state = state;

     if (h->is_avc)

         return next_avc;

     return END_NOT_FOUND;

 
 found:

     pc->state             = 7;
     pc->frame_start_found = 0;

     if (h->is_avc)

         return next_avc;

     return i - (state & 5) - 3 * (state > 7);

 }
 

 static int scan_mmco_reset(AVCodecParserContext *s)
 {
     H264Context *h = s->priv_data;
 
     h->slice_type_nos = s->pict_type & 3;
 
     if (h->pps.redundant_pic_cnt_present)
         get_ue_golomb(&h->gb); // redundant_pic_count
 
     if (ff_set_ref_count(h) < 0)
         return AVERROR_INVALIDDATA;
 
     if (h->slice_type_nos != AV_PICTURE_TYPE_I) {
         int list;
         for (list = 0; list < h->list_count; list++) {
             if (get_bits1(&h->gb)) {
                 int index;
                 for (index = 0; ; index++) {
                     unsigned int reordering_of_pic_nums_idc = get_ue_golomb_31(&h->gb);
 
                     if (reordering_of_pic_nums_idc < 3)
                         get_ue_golomb(&h->gb);
                     else if (reordering_of_pic_nums_idc > 3) {
                         av_log(h->avctx, AV_LOG_ERROR,
                                "illegal reordering_of_pic_nums_idc %d\n",
                                reordering_of_pic_nums_idc);
                         return AVERROR_INVALIDDATA;
                     } else
                         break;
 
                     if (index >= h->ref_count[list]) {

                         av_log(h->avctx, AV_LOG_ERROR,
                                "reference count %d overflow\n", index);

                         return AVERROR_INVALIDDATA;
                     }
                 }
             }
         }
     }
 
     if ((h->pps.weighted_pred && h->slice_type_nos == AV_PICTURE_TYPE_P) ||
         (h->pps.weighted_bipred_idc == 1 && h->slice_type_nos == AV_PICTURE_TYPE_B))
         ff_pred_weight_table(h);
 
     if (get_bits1(&h->gb)) { // adaptive_ref_pic_marking_mode_flag
         int i;
         for (i = 0; i < MAX_MMCO_COUNT; i++) {
             MMCOOpcode opcode = get_ue_golomb_31(&h->gb);
             if (opcode > (unsigned) MMCO_LONG) {
                 av_log(h->avctx, AV_LOG_ERROR,
                        "illegal memory management control operation %d\n",
                        opcode);
                 return AVERROR_INVALIDDATA;
             }
             if (opcode == MMCO_END)
                return 0;
             else if (opcode == MMCO_RESET)
                 return 1;
 
             if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG)
                 get_ue_golomb(&h->gb);
             if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
                 opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG)
                 get_ue_golomb_31(&h->gb);
         }
     }
 
     return 0;
 }
 

 /**

  * Parse NAL units of found picture and decode some basic information.
  *
  * @param s parser context.
  * @param avctx codec context.
  * @param buf buffer with field/frame data.
  * @param buf_size size of the buffer.
  */
 static inline int parse_nal_units(AVCodecParserContext *s,
                                   AVCodecContext *avctx,
                                   const uint8_t *buf, int buf_size)
 {

     H264Context *h         = s->priv_data;

     const uint8_t *buf_end = buf + buf_size;

     unsigned int pps_id;

     unsigned int slice_type;

     int state = -1, got_reset = 0;

     const uint8_t *ptr;

     int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);

     int field_poc[2];

 
     /* set some sane default values */

     s->pict_type         = AV_PICTURE_TYPE_I;
     s->key_frame         = 0;

     s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;

     h->avctx = avctx;
     ff_h264_reset_sei(h);

     h->sei_fpa.frame_packing_arrangement_cancel_flag = -1;

     if (!buf_size)
         return 0;
 

     for (;;) {

         int src_length, dst_length, consumed, nalsize = 0;
         if (h->is_avc) {
             int i;
             if (h->nal_length_size >= buf_end - buf) break;
             nalsize = 0;
             for (i = 0; i < h->nal_length_size; i++)
                 nalsize = (nalsize << 8) | *buf++;
             if (nalsize <= 0 || nalsize > buf_end - buf) {

                 av_log(h->avctx, AV_LOG_ERROR, "AVC: nal size %d\n", nalsize);

                 break;
             }
             src_length = nalsize;
         } else {

         buf = avpriv_find_start_code(buf, buf_end, &state);

         if (buf >= buf_end)

             break;
         --buf;
         src_length = buf_end - buf;

         }

         switch (state & 0x1f) {
         case NAL_SLICE:
         case NAL_IDR_SLICE:
             // Do not walk the whole buffer just to decode slice header

             if ((state & 0x1f) == NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {

                 /* IDR or disposable slice
                  * No need to decode many bytes because MMCOs shall not be present. */
                 if (src_length > 60)
                     src_length = 60;
             } else {
                 /* To decode up to MMCOs */
                 if (src_length > 1000)
                     src_length = 1000;
             }

             break;
         }

         ptr = ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
         if (ptr == NULL || dst_length < 0)

             break;
 

         init_get_bits(&h->gb, ptr, 8 * dst_length);
         switch (h->nal_unit_type) {

         case NAL_SPS:
             ff_h264_decode_seq_parameter_set(h);
             break;
         case NAL_PPS:

             ff_h264_decode_picture_parameter_set(h, h->gb.size_in_bits);

             break;
         case NAL_SEI:
             ff_h264_decode_sei(h);
             break;
         case NAL_IDR_SLICE:

             s->key_frame = 1;

 
             h->prev_frame_num        = 0;
             h->prev_frame_num_offset = 0;
             h->prev_poc_msb          =
             h->prev_poc_lsb          = 0;

         /* fall through */

         case NAL_SLICE:

             get_ue_golomb_long(&h->gb);  // skip first_mb_in_slice

             slice_type   = get_ue_golomb_31(&h->gb);

             s->pict_type = golomb_to_pict_type[slice_type % 5];

             if (h->sei_recovery_frame_cnt >= 0) {
                 /* key frame, since recovery_frame_cnt is set */
                 s->key_frame = 1;
             }

             pps_id = get_ue_golomb(&h->gb);
             if (pps_id >= MAX_PPS_COUNT) {
                 av_log(h->avctx, AV_LOG_ERROR,

                        "pps_id %u out of range\n", pps_id);

                 return -1;
             }

             if (!h->pps_buffers[pps_id]) {
                 av_log(h->avctx, AV_LOG_ERROR,

                        "non-existing PPS %u referenced\n", pps_id);

                 return -1;
             }

             h->pps = *h->pps_buffers[pps_id];
             if (!h->sps_buffers[h->pps.sps_id]) {
                 av_log(h->avctx, AV_LOG_ERROR,

                        "non-existing SPS %u referenced\n", h->pps.sps_id);

                 return -1;
             }

             h->sps       = *h->sps_buffers[h->pps.sps_id];

             h->frame_num = get_bits(&h->gb, h->sps.log2_max_frame_num);

             if(h->sps.ref_frame_count <= 1 && h->pps.ref_count[0] <= 1 && s->pict_type == AV_PICTURE_TYPE_I)
                 s->key_frame = 1;
 

             avctx->profile = ff_h264_get_profile(&h->sps);

             avctx->level   = h->sps.level_idc;
 

             if (h->sps.frame_mbs_only_flag) {
                 h->picture_structure = PICT_FRAME;
             } else {
                 if (get_bits1(&h->gb)) { // field_pic_flag
                     h->picture_structure = PICT_TOP_FIELD + get_bits1(&h->gb); // bottom_field_flag

                 } else {

                     h->picture_structure = PICT_FRAME;

                 }
             }
 

             if (h->nal_unit_type == NAL_IDR_SLICE)
                 get_ue_golomb(&h->gb); /* idr_pic_id */
             if (h->sps.poc_type == 0) {
                 h->poc_lsb = get_bits(&h->gb, h->sps.log2_max_poc_lsb);
 

                 if (h->pps.pic_order_present == 1 &&
                     h->picture_structure == PICT_FRAME)

                     h->delta_poc_bottom = get_se_golomb(&h->gb);
             }
 

             if (h->sps.poc_type == 1 &&
                 !h->sps.delta_pic_order_always_zero_flag) {

                 h->delta_poc[0] = get_se_golomb(&h->gb);
 

                 if (h->pps.pic_order_present == 1 &&
                     h->picture_structure == PICT_FRAME)

                     h->delta_poc[1] = get_se_golomb(&h->gb);
             }
 

             /* Decode POC of this picture.
              * The prev_ values needed for decoding POC of the next picture are not set here. */

             field_poc[0] = field_poc[1] = INT_MAX;

             ff_init_poc(h, field_poc, &s->output_picture_number);

             /* Continue parsing to check if MMCO_RESET is present.
              * FIXME: MMCO_RESET could appear in non-first slice.
              *        Maybe, we should parse all undisposable non-IDR slice of this
              *        picture until encountering MMCO_RESET in a slice of it. */
             if (h->nal_ref_idc && h->nal_unit_type != NAL_IDR_SLICE) {
                 got_reset = scan_mmco_reset(s);
                 if (got_reset < 0)
                     return got_reset;
             }
 

             /* Set up the prev_ values for decoding POC of the next picture. */

             h->prev_frame_num        = got_reset ? 0 : h->frame_num;
             h->prev_frame_num_offset = got_reset ? 0 : h->frame_num_offset;

             if (h->nal_ref_idc != 0) {

                 if (!got_reset) {
                     h->prev_poc_msb = h->poc_msb;
                     h->prev_poc_lsb = h->poc_lsb;
                 } else {
                     h->prev_poc_msb = 0;
                     h->prev_poc_lsb =
                         h->picture_structure == PICT_BOTTOM_FIELD ? 0 : field_poc[0];
                 }

             }
 

             if (h->sps.pic_struct_present_flag) {

                 switch (h->sei_pic_struct) {

                 case SEI_PIC_STRUCT_TOP_FIELD:
                 case SEI_PIC_STRUCT_BOTTOM_FIELD:
                     s->repeat_pict = 0;
                     break;
                 case SEI_PIC_STRUCT_FRAME:
                 case SEI_PIC_STRUCT_TOP_BOTTOM:
                 case SEI_PIC_STRUCT_BOTTOM_TOP:
                     s->repeat_pict = 1;
                     break;
                 case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
                 case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
                     s->repeat_pict = 2;
                     break;
                 case SEI_PIC_STRUCT_FRAME_DOUBLING:
                     s->repeat_pict = 3;
                     break;
                 case SEI_PIC_STRUCT_FRAME_TRIPLING:
                     s->repeat_pict = 5;
                     break;
                 default:
                     s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;
                     break;

                 }
             } else {

                 s->repeat_pict = h->picture_structure == PICT_FRAME ? 1 : 0;

             }
 

             if (h->picture_structure == PICT_FRAME) {
                 s->picture_structure = AV_PICTURE_STRUCTURE_FRAME;
                 if (h->sps.pic_struct_present_flag) {
                     switch (h->sei_pic_struct) {

                     case SEI_PIC_STRUCT_TOP_BOTTOM:
                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
                         s->field_order = AV_FIELD_TT;
                         break;
                     case SEI_PIC_STRUCT_BOTTOM_TOP:
                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:
                         s->field_order = AV_FIELD_BB;
                         break;
                     default:
                         s->field_order = AV_FIELD_PROGRESSIVE;
                         break;

                     }
                 } else {
                     if (field_poc[0] < field_poc[1])
                         s->field_order = AV_FIELD_TT;
                     else if (field_poc[0] > field_poc[1])
                         s->field_order = AV_FIELD_BB;
                     else
                         s->field_order = AV_FIELD_PROGRESSIVE;
                 }
             } else {
                 if (h->picture_structure == PICT_TOP_FIELD)
                     s->picture_structure = AV_PICTURE_STRUCTURE_TOP_FIELD;
                 else
                     s->picture_structure = AV_PICTURE_STRUCTURE_BOTTOM_FIELD;
                 s->field_order = AV_FIELD_UNKNOWN;
             }
 

             return 0; /* no need to evaluate the rest */
         }

         buf += h->is_avc ? nalsize : consumed;

     }

     if (q264)
         return 0;

     /* didn't find a picture! */

     av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);

     return -1;
 }
 

 static int h264_parse(AVCodecParserContext *s,
                       AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
 {

     H264Context *h   = s->priv_data;

     ParseContext *pc = &h->parse_context;

     int next;
 

     if (!h->got_first) {
         h->got_first = 1;

         if (avctx->extradata_size) {

             h->avctx = avctx;

             // must be done like in decoder, otherwise opening the parser,
             // letting it create extradata and then closing and opening again
             // will cause has_b_frames to be always set.
             // Note that estimate_timings_from_pts does exactly this.
             if (!avctx->has_b_frames)

                 h->low_delay = 1;

             ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);

         }
     }
 

     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
         next = buf_size;
     } else {

         next = h264_find_frame_end(h, buf, buf_size);

 
         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

             *poutbuf      = NULL;

             *poutbuf_size = 0;
             return buf_size;
         }
 

         if (next < 0 && next != END_NOT_FOUND) {

             av_assert1(pc->last_index + next >= 0);

             h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); // update state

         }

     }

     parse_nal_units(s, avctx, buf, buf_size);

     if (h->sei_cpb_removal_delay >= 0) {
         s->dts_sync_point    = h->sei_buffering_period_present;
         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
         s->pts_dts_delta     = h->sei_dpb_output_delay;
     } else {
         s->dts_sync_point    = INT_MIN;
         s->dts_ref_dts_delta = INT_MIN;
         s->pts_dts_delta     = INT_MIN;
     }

     if (s->flags & PARSER_FLAG_ONCE) {
         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
     }

     *poutbuf      = buf;

     *poutbuf_size = buf_size;
     return next;
 }
 
 static int h264_split(AVCodecContext *avctx,
                       const uint8_t *buf, int buf_size)
 {
     int i;
     uint32_t state = -1;

     int has_sps    = 0;
 
     for (i = 0; i <= buf_size; i++) {
         if ((state & 0xFFFFFF1F) == 0x107)
             has_sps = 1;

         /*  if ((state&0xFFFFFF1F) == 0x101 ||

          *     (state&0xFFFFFF1F) == 0x102 ||
          *     (state&0xFFFFFF1F) == 0x105) {
          *  }
          */
         if ((state & 0xFFFFFF00) == 0x100 && (state & 0xFFFFFF1F) != 0x107 &&
             (state & 0xFFFFFF1F) != 0x108 && (state & 0xFFFFFF1F) != 0x109) {
             if (has_sps) {
                 while (i > 4 && buf[i - 5] == 0)
                     i--;
                 return i - 4;

             }
         }

         if (i < buf_size)
             state = (state << 8) | buf[i];

     }
     return 0;
 }
 

 static void close(AVCodecParserContext *s)

 {

     H264Context *h   = s->priv_data;

     ParseContext *pc = &h->parse_context;

 
     av_free(pc->buffer);

     ff_h264_free_context(h);

 }
 

 static av_cold int init(AVCodecParserContext *s)

 {
     H264Context *h = s->priv_data;

     h->thread_context[0]   = h;

     h->slice_context_count = 1;

     ff_h264dsp_init(&h->h264dsp, 8, 1);

     return 0;
 }

 AVCodecParser ff_h264_parser = {

     .codec_ids      = { AV_CODEC_ID_H264 },

     .priv_data_size = sizeof(H264Context),
     .parser_init    = init,
     .parser_parse   = h264_parse,
     .parser_close   = close,
     .split          = h264_split,

 };