Subversion Repositories Kolibri OS

Rev

Go to most recent revision | Blame | Last modification | View Log | RSS feed

  1. /*
  2.  * H261 parser
  3.  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
  4.  * Copyright (c) 2004 Maarten Daniels
  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. /**
  24.  * @file
  25.  * h261codec.
  26.  */
  27.  
  28. #include "parser.h"
  29.  
  30. static int h261_find_frame_end(ParseContext *pc, AVCodecContext *avctx,
  31.                                const uint8_t *buf, int buf_size)
  32. {
  33.     int vop_found, i, j;
  34.     uint32_t state;
  35.  
  36.     vop_found = pc->frame_start_found;
  37.     state     = pc->state;
  38.  
  39.     for (i = 0; i < buf_size && !vop_found; i++) {
  40.         state = (state << 8) | buf[i];
  41.         for (j = 0; j < 8; j++) {
  42.             if (((state >> j) & 0xFFFFF0) == 0x000100) {
  43.                 vop_found = 1;
  44.                 break;
  45.             }
  46.         }
  47.     }
  48.     if (vop_found) {
  49.         for (; i < buf_size; i++) {
  50.             state = (state << 8) | buf[i];
  51.             for (j = 0; j < 8; j++) {
  52.                 if (((state >> j) & 0xFFFFF0) == 0x000100) {
  53.                     pc->frame_start_found = 0;
  54.                     pc->state             = (state >> (3 * 8)) + 0xFF00;
  55.                     return i - 2;
  56.                 }
  57.             }
  58.         }
  59.     }
  60.  
  61.     pc->frame_start_found = vop_found;
  62.     pc->state             = state;
  63.     return END_NOT_FOUND;
  64. }
  65.  
  66. static int h261_parse(AVCodecParserContext *s,
  67.                       AVCodecContext *avctx,
  68.                       const uint8_t **poutbuf, int *poutbuf_size,
  69.                       const uint8_t *buf, int buf_size)
  70. {
  71.     ParseContext *pc = s->priv_data;
  72.     int next;
  73.  
  74.     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
  75.         next = buf_size;
  76.     } else {
  77.         next = h261_find_frame_end(pc, avctx, buf, buf_size);
  78.         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
  79.             *poutbuf      = NULL;
  80.             *poutbuf_size = 0;
  81.             return buf_size;
  82.         }
  83.     }
  84.     *poutbuf      = buf;
  85.     *poutbuf_size = buf_size;
  86.     return next;
  87. }
  88.  
  89. AVCodecParser ff_h261_parser = {
  90.     .codec_ids      = { AV_CODEC_ID_H261 },
  91.     .priv_data_size = sizeof(ParseContext),
  92.     .parser_parse   = h261_parse,
  93.     .parser_close   = ff_parse_close,
  94. };
  95.