libavcodec/cavs_parser.c

   1 /*
   2  * Chinese AVS video (AVS1-P2, JiZhun profile) parser.
   3  * Copyright (c) 2006  Stefan Gehrer <stefan.gehrer@gmx.de>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * Chinese AVS video (AVS1-P2, JiZhun profile) parser
  25  * @author Stefan Gehrer <stefan.gehrer@gmx.de>
  26  */
  27
  28 #include "parser.h"
  29 #include "cavs.h"
  30
  31
  32 /**
  33  * Find the end of the current frame in the bitstream.
  34  * @return the position of the first byte of the next frame, or -1
  35  */
  36 static int cavs_find_frame_end(ParseContext *pc, const uint8_t *buf,
  37                                int buf_size) {
  38     int pic_found, i;
  39     uint32_t state;
  40
  41     pic_found= pc->frame_start_found;
  42     state= pc->state;
  43
  44     i=0;
  45     if(!pic_found){
  46         for(i=0; i<buf_size; i++){
  47             state= (state<<8) | buf[i];
  48             if(state == PIC_I_START_CODE || state == PIC_PB_START_CODE){
  49                 i++;
  50                 pic_found=1;
  51                 break;
  52             }
  53         }
  54     }
  55
  56     if(pic_found){
  57         /* EOF considered as end of frame */
  58         if (buf_size == 0)
  59             return 0;
  60         for(; i<buf_size; i++){
  61             state= (state<<8) | buf[i];
  62             if (state == PIC_I_START_CODE || state == PIC_PB_START_CODE ||
  63                     state == CAVS_START_CODE) {
  64                 pc->frame_start_found=0;
  65                 pc->state=-1;
  66                 return i-3;
  67             }
  68         }
  69     }
  70     pc->frame_start_found= pic_found;
  71     pc->state= state;
  72     return END_NOT_FOUND;
  73 }
  74
  75 static int cavsvideo_parse(AVCodecParserContext *s,
  76                            AVCodecContext *avctx,
  77                            const uint8_t **poutbuf, int *poutbuf_size,
  78                            const uint8_t *buf, int buf_size)
  79 {
  80     ParseContext *pc = s->priv_data;
  81     int next;
  82
  83     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
  84         next= buf_size;
  85     }else{
  86         next= cavs_find_frame_end(pc, buf, buf_size);
  87
  88         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
  89             *poutbuf = NULL;
  90             *poutbuf_size = 0;
  91             return buf_size;
  92         }
  93     }
  94     *poutbuf = buf;
  95     *poutbuf_size = buf_size;
  96     return next;
  97 }
  98
  99 const AVCodecParser ff_cavsvideo_parser = {
 100     .codec_ids      = { AV_CODEC_ID_CAVS },
 101     .priv_data_size = sizeof(ParseContext),
 102     .parser_parse   = cavsvideo_parse,
 103     .parser_close   = ff_parse_close,
 104 };