libavcodec/vc1_parser.c

   1 /*
   2  * VC-1 and WMV3 parser
   3  * Copyright (c) 2006-2007 Konstantin Shishkov
   4  * Partly based on vc9.c (c) 2005 Anonymous, Alex Beregszaszi, 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 /**
  24  * @file vc1_parser.c
  25  * VC-1 and WMV3 parser
  26  */
  27
  28 #include "parser.h"
  29 #include "vc1.h"
  30
  31 /**
  32  * finds the end of the current frame in the bitstream.
  33  * @return the position of the first byte of the next frame, or -1
  34  */
  35 static int vc1_find_frame_end(ParseContext *pc, const uint8_t *buf,
  36                                int buf_size) {
  37     int pic_found, i;
  38     uint32_t state;
  39
  40     pic_found= pc->frame_start_found;
  41     state= pc->state;
  42
  43     i=0;
  44     if(!pic_found){
  45         for(i=0; i<buf_size; i++){
  46             state= (state<<8) | buf[i];
  47             if(state == VC1_CODE_FRAME || state == VC1_CODE_FIELD){
  48                 i++;
  49                 pic_found=1;
  50                 break;
  51             }
  52         }
  53     }
  54
  55     if(pic_found){
  56         /* EOF considered as end of frame */
  57         if (buf_size == 0)
  58             return 0;
  59         for(; i<buf_size; i++){
  60             state= (state<<8) | buf[i];
  61             if(IS_MARKER(state) && state != VC1_CODE_FIELD && state != VC1_CODE_SLICE){
  62                 pc->frame_start_found=0;
  63                 pc->state=-1;
  64                 return i-3;
  65             }
  66         }
  67     }
  68     pc->frame_start_found= pic_found;
  69     pc->state= state;
  70     return END_NOT_FOUND;
  71 }
  72
  73 static int vc1_parse(AVCodecParserContext *s,
  74                            AVCodecContext *avctx,
  75                            const uint8_t **poutbuf, int *poutbuf_size,
  76                            const uint8_t *buf, int buf_size)
  77 {
  78     ParseContext *pc = s->priv_data;
  79     int next;
  80
  81     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
  82         next= buf_size;
  83     }else{
  84         next= vc1_find_frame_end(pc, buf, buf_size);
  85
  86         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
  87             *poutbuf = NULL;
  88             *poutbuf_size = 0;
  89             return buf_size;
  90         }
  91     }
  92     *poutbuf = buf;
  93     *poutbuf_size = buf_size;
  94     return next;
  95 }
  96
  97 static int vc1_split(AVCodecContext *avctx,
  98                            const uint8_t *buf, int buf_size)
  99 {
 100     int i;
 101     uint32_t state= -1;
 102
 103     for(i=0; i<buf_size; i++){
 104         state= (state<<8) | buf[i];
 105         if(IS_MARKER(state) && state != VC1_CODE_SEQHDR && state != VC1_CODE_ENTRYPOINT)
 106             return i-3;
 107     }
 108     return 0;
 109 }
 110
 111 AVCodecParser vc1_parser = {
 112     { CODEC_ID_VC1 },
 113     sizeof(ParseContext1),
 114     NULL,
 115     vc1_parse,
 116     ff_parse1_close,
 117     vc1_split,
 118 };