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  1. /*
  2.  * MPEG4 Video frame extraction
  3.  * Copyright (c) 2003 Fabrice Bellard
  4.  * Copyright (c) 2003 Michael Niedermayer
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. #define UNCHECKED_BITSTREAM_READER 1
  24.  
  25. #include "internal.h"
  26. #include "parser.h"
  27. #include "mpegvideo.h"
  28. #include "mpeg4video.h"
  29. #include "mpeg4video_parser.h"
  30.  
  31. struct Mp4vParseContext {
  32.     ParseContext pc;
  33.     Mpeg4DecContext dec_ctx;
  34.     int first_picture;
  35. };
  36.  
  37. int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
  38. {
  39.     int vop_found, i;
  40.     uint32_t state;
  41.  
  42.     vop_found = pc->frame_start_found;
  43.     state     = pc->state;
  44.  
  45.     i = 0;
  46.     if (!vop_found) {
  47.         for (i = 0; i < buf_size; i++) {
  48.             state = (state << 8) | buf[i];
  49.             if (state == 0x1B6) {
  50.                 i++;
  51.                 vop_found = 1;
  52.                 break;
  53.             }
  54.         }
  55.     }
  56.  
  57.     if (vop_found) {
  58.         /* EOF considered as end of frame */
  59.         if (buf_size == 0)
  60.             return 0;
  61.         for (; i < buf_size; i++) {
  62.             state = (state << 8) | buf[i];
  63.             if ((state & 0xFFFFFF00) == 0x100) {
  64.                 pc->frame_start_found = 0;
  65.                 pc->state             = -1;
  66.                 return i - 3;
  67.             }
  68.         }
  69.     }
  70.     pc->frame_start_found = vop_found;
  71.     pc->state             = state;
  72.     return END_NOT_FOUND;
  73. }
  74.  
  75. /* XXX: make it use less memory */
  76. static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx,
  77.                                const uint8_t *buf, int buf_size)
  78. {
  79.     struct Mp4vParseContext *pc = s1->priv_data;
  80.     Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
  81.     MpegEncContext *s = &dec_ctx->m;
  82.     GetBitContext gb1, *gb = &gb1;
  83.     int ret;
  84.  
  85.     s->avctx               = avctx;
  86.     s->current_picture_ptr = &s->current_picture;
  87.  
  88.     if (avctx->extradata_size && pc->first_picture) {
  89.         init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
  90.         ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
  91.         if (ret < -1)
  92.             av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata\n");
  93.     }
  94.  
  95.     init_get_bits(gb, buf, 8 * buf_size);
  96.     ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
  97.     if (s->width && (!avctx->width || !avctx->height ||
  98.                      !avctx->coded_width || !avctx->coded_height)) {
  99.         ret = ff_set_dimensions(avctx, s->width, s->height);
  100.         if (ret < 0)
  101.             return ret;
  102.     }
  103.     if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->time_base.den>0 && ret>=0){
  104.         av_assert1(s1->pts == AV_NOPTS_VALUE);
  105.         av_assert1(s1->dts == AV_NOPTS_VALUE);
  106.  
  107.         s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->time_base.den}, (AVRational){1, 1200000});
  108.     }
  109.  
  110.     s1->pict_type     = s->pict_type;
  111.     pc->first_picture = 0;
  112.     return ret;
  113. }
  114.  
  115. static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
  116. {
  117.     struct Mp4vParseContext *pc = s->priv_data;
  118.  
  119.     ff_mpeg4videodec_static_init();
  120.  
  121.     pc->first_picture           = 1;
  122.     pc->dec_ctx.m.quant_precision     = 5;
  123.     pc->dec_ctx.m.slice_context_count = 1;
  124.     pc->dec_ctx.showed_packed_warning = 1;
  125.     return 0;
  126. }
  127.  
  128. static int mpeg4video_parse(AVCodecParserContext *s,
  129.                             AVCodecContext *avctx,
  130.                             const uint8_t **poutbuf, int *poutbuf_size,
  131.                             const uint8_t *buf, int buf_size)
  132. {
  133.     ParseContext *pc = s->priv_data;
  134.     int next;
  135.  
  136.     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
  137.         next = buf_size;
  138.     } else {
  139.         next = ff_mpeg4_find_frame_end(pc, buf, buf_size);
  140.  
  141.         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
  142.             *poutbuf      = NULL;
  143.             *poutbuf_size = 0;
  144.             return buf_size;
  145.         }
  146.     }
  147.     mpeg4_decode_header(s, avctx, buf, buf_size);
  148.  
  149.     *poutbuf      = buf;
  150.     *poutbuf_size = buf_size;
  151.     return next;
  152. }
  153.  
  154. AVCodecParser ff_mpeg4video_parser = {
  155.     .codec_ids      = { AV_CODEC_ID_MPEG4 },
  156.     .priv_data_size = sizeof(struct Mp4vParseContext),
  157.     .parser_init    = mpeg4video_parse_init,
  158.     .parser_parse   = mpeg4video_parse,
  159.     .parser_close   = ff_parse_close,
  160.     .split          = ff_mpeg4video_split,
  161. };
  162.