/*
  * VC-1 and WMV3 parser
  * Copyright (c) 2006-2007 Konstantin Shishkov
  * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, Michael Niedermayer
  *
  * 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

  * VC-1 and WMV3 parser
  */

 #include "libavutil/attributes.h"

 #include "parser.h"
 #include "vc1.h"

 #include "get_bits.h"

 #include "internal.h"

 /** The maximum number of bytes of a sequence, entry point or
  *  frame header whose values we pay any attention to */
 #define UNESCAPED_THRESHOLD 37
 
 /** The maximum number of bytes of a sequence, entry point or
  *  frame header which must be valid memory (because they are
  *  used to update the bitstream cache in skip_bits() calls)
  */
 #define UNESCAPED_LIMIT 144
 
 typedef enum {
     NO_MATCH,
     ONE_ZERO,
     TWO_ZEROS,
     ONE
 } VC1ParseSearchState;
 

 typedef struct VC1ParseContext {

     ParseContext pc;
     VC1Context v;

     uint8_t prev_start_code;
     size_t bytes_to_skip;
     uint8_t unesc_buffer[UNESCAPED_LIMIT];
     size_t unesc_index;
     VC1ParseSearchState search_state;

 } VC1ParseContext;
 

 static void vc1_extract_header(AVCodecParserContext *s, AVCodecContext *avctx,
                                const uint8_t *buf, int buf_size)

 {

     /* Parse the header we just finished unescaping */

     VC1ParseContext *vpc = s->priv_data;
     GetBitContext gb;

     int ret;

     vpc->v.s.avctx = avctx;
     vpc->v.parse_only = 1;

     init_get_bits(&gb, buf, buf_size * 8);
     switch (vpc->prev_start_code) {
     case VC1_CODE_SEQHDR & 0xFF:
         ff_vc1_decode_sequence_header(avctx, &vpc->v, &gb);
         break;
     case VC1_CODE_ENTRYPOINT & 0xFF:
         ff_vc1_decode_entry_point(avctx, &vpc->v, &gb);
         break;
     case VC1_CODE_FRAME & 0xFF:
         if(vpc->v.profile < PROFILE_ADVANCED)
             ret = ff_vc1_parse_frame_header    (&vpc->v, &gb);
         else
             ret = ff_vc1_parse_frame_header_adv(&vpc->v, &gb);

         if (ret < 0)

             break;
 

         /* keep AV_PICTURE_TYPE_BI internal to VC1 */
         if (vpc->v.s.pict_type == AV_PICTURE_TYPE_BI)
             s->pict_type = AV_PICTURE_TYPE_B;
         else
             s->pict_type = vpc->v.s.pict_type;

         if (avctx->ticks_per_frame > 1){
             // process pulldown flags
             s->repeat_pict = 1;
             // Pulldown flags are only valid when 'broadcast' has been set.
             // So ticks_per_frame will be 2
             if (vpc->v.rff){
                 // repeat field
                 s->repeat_pict = 2;
             }else if (vpc->v.rptfrm){
                 // repeat frames
                 s->repeat_pict = vpc->v.rptfrm * 2 + 1;

             }

         }else{
             s->repeat_pict = 0;

         }
 

         if (vpc->v.broadcast && vpc->v.interlace && !vpc->v.psf)
             s->field_order = vpc->v.tff ? AV_FIELD_TT : AV_FIELD_BB;
         else
             s->field_order = AV_FIELD_PROGRESSIVE;
 
         break;

     }

     if (avctx->framerate.num)
         avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));

     s->format = vpc->v.chromaformat == 1 ? AV_PIX_FMT_YUV420P
                                          : AV_PIX_FMT_NONE;
     if (avctx->width && avctx->height) {
         s->width        = avctx->width;
         s->height       = avctx->height;
         s->coded_width  = FFALIGN(avctx->coded_width,  16);
         s->coded_height = FFALIGN(avctx->coded_height, 16);
     }

 }
 
 static int vc1_parse(AVCodecParserContext *s,
                            AVCodecContext *avctx,

                            const uint8_t **poutbuf, int *poutbuf_size,

                            const uint8_t *buf, int buf_size)
 {

     /* Here we do the searching for frame boundaries and headers at
      * the same time. Only a minimal amount at the start of each
      * header is unescaped. */

     VC1ParseContext *vpc = s->priv_data;

     int pic_found = vpc->pc.frame_start_found;
     uint8_t *unesc_buffer = vpc->unesc_buffer;
     size_t unesc_index = vpc->unesc_index;
     VC1ParseSearchState search_state = vpc->search_state;

     int start_code_found = 0;

     int next = END_NOT_FOUND;
     int i = vpc->bytes_to_skip;
 
     if (pic_found && buf_size == 0) {
         /* EOF considered as end of frame */
         memset(unesc_buffer + unesc_index, 0, UNESCAPED_THRESHOLD - unesc_index);
         vc1_extract_header(s, avctx, unesc_buffer, unesc_index);
         next = 0;
     }
     while (i < buf_size) {
         uint8_t b;

         start_code_found = 0;

         while (i < buf_size && unesc_index < UNESCAPED_THRESHOLD) {
             b = buf[i++];
             unesc_buffer[unesc_index++] = b;
             if (search_state <= ONE_ZERO)
                 search_state = b ? NO_MATCH : search_state + 1;
             else if (search_state == TWO_ZEROS) {
                 if (b == 1)
                     search_state = ONE;
                 else if (b > 1) {
                     if (b == 3)
                         unesc_index--; // swallow emulation prevention byte
                     search_state = NO_MATCH;
                 }
             }
             else { // search_state == ONE
                 // Header unescaping terminates early due to detection of next start code
                 search_state = NO_MATCH;
                 start_code_found = 1;
                 break;
             }
         }
         if ((s->flags & PARSER_FLAG_COMPLETE_FRAMES) &&
                 unesc_index >= UNESCAPED_THRESHOLD &&
                 vpc->prev_start_code == (VC1_CODE_FRAME & 0xFF))
         {
             // No need to keep scanning the rest of the buffer for
             // start codes if we know it contains a complete frame and
             // we've already unescaped all we need of the frame header
             vc1_extract_header(s, avctx, unesc_buffer, unesc_index);
             break;
         }
         if (unesc_index >= UNESCAPED_THRESHOLD && !start_code_found) {
             while (i < buf_size) {
                 if (search_state == NO_MATCH) {

                     i += vpc->v.vc1dsp.startcode_find_candidate(buf + i, buf_size - i);

                     if (i < buf_size) {
                         search_state = ONE_ZERO;
                     }
                     i++;
                 } else {
                     b = buf[i++];
                     if (search_state == ONE_ZERO)
                         search_state = b ? NO_MATCH : TWO_ZEROS;
                     else if (search_state == TWO_ZEROS) {
                         if (b >= 1)
                             search_state = b == 1 ? ONE : NO_MATCH;
                     }
                     else { // search_state == ONE
                         search_state = NO_MATCH;
                         start_code_found = 1;
                         break;
                     }
                 }
             }
         }
         if (start_code_found) {
             vc1_extract_header(s, avctx, unesc_buffer, unesc_index);
 
             vpc->prev_start_code = b;
             unesc_index = 0;
 
             if (!(s->flags & PARSER_FLAG_COMPLETE_FRAMES)) {
                 if (!pic_found && (b == (VC1_CODE_FRAME & 0xFF) || b == (VC1_CODE_FIELD & 0xFF))) {
                     pic_found = 1;
                 }
                 else if (pic_found && b != (VC1_CODE_FIELD & 0xFF) && b != (VC1_CODE_SLICE & 0xFF)) {
                     next = i - 4;
                     pic_found = b == (VC1_CODE_FRAME & 0xFF);
                     break;
                 }
             }
         }
     }

     vpc->pc.frame_start_found = pic_found;
     vpc->unesc_index = unesc_index;
     vpc->search_state = search_state;

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

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

             vpc->bytes_to_skip = 0;

             *poutbuf = NULL;
             *poutbuf_size = 0;
             return buf_size;
         }
     }

     /* If we return with a valid pointer to a combined frame buffer
      * then on the next call then we'll have been unhelpfully rewound
      * by up to 4 bytes (depending upon whether the start code
      * overlapped the input buffer, and if so by how much). We don't
      * want this: it will either cause spurious second detections of
      * the start code we've already seen, or cause extra bytes to be
      * inserted at the start of the unescaped buffer. */
     vpc->bytes_to_skip = 4;

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

         vpc->bytes_to_skip += next;

     *poutbuf = buf;

     *poutbuf_size = buf_size;
     return next;
 }
 
 static int vc1_split(AVCodecContext *avctx,
                            const uint8_t *buf, int buf_size)
 {

     uint32_t state = -1;
     int charged = 0;
     const uint8_t *ptr = buf, *end = buf + buf_size;

     while (ptr < end) {
         ptr = avpriv_find_start_code(ptr, end, &state);
         if (state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT) {
             charged = 1;
         } else if (charged && IS_MARKER(state))
             return ptr - 4 - buf;

     }

     return 0;
 }
 

 static av_cold int vc1_parse_init(AVCodecParserContext *s)

 {
     VC1ParseContext *vpc = s->priv_data;
     vpc->v.s.slice_context_count = 1;

     vpc->v.first_pic_header_flag = 1;
     vpc->prev_start_code = 0;
     vpc->bytes_to_skip = 0;
     vpc->unesc_index = 0;
     vpc->search_state = NO_MATCH;

     return ff_vc1_init_common(&vpc->v);

 }
 

 AVCodecParser ff_vc1_parser = {

     .codec_ids      = { AV_CODEC_ID_VC1 },

     .priv_data_size = sizeof(VC1ParseContext),

     .parser_init    = vc1_parse_init,

     .parser_parse   = vc1_parse,

     .parser_close   = ff_parse_close,

     .split          = vc1_split,

 };