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 libavcodec/cavs_parser.c
  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  * finds 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&0xFFFFFF00) == 0x100){
  63                 if(state > SLICE_MAX_START_CODE){
  64                     pc->frame_start_found=0;
  65                     pc->state=-1;
  66                     return i-3;
  67                 }
  68             }
  69         }
  70     }
  71     pc->frame_start_found= pic_found;
  72     pc->state= state;
  73     return END_NOT_FOUND;
  74 }
  75
  76 static int cavsvideo_parse(AVCodecParserContext *s,
  77                            AVCodecContext *avctx,
  78                            const uint8_t **poutbuf, int *poutbuf_size,
  79                            const uint8_t *buf, int buf_size)
  80 {
  81     ParseContext *pc = s->priv_data;
  82     int next;
  83
  84     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
  85         next= buf_size;
  86     }else{
  87         next= cavs_find_frame_end(pc, buf, buf_size);
  88
  89         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
  90             *poutbuf = NULL;
  91             *poutbuf_size = 0;
  92             return buf_size;
  93         }
  94     }
  95     *poutbuf = buf;
  96     *poutbuf_size = buf_size;
  97     return next;
  98 }
  99
 100 AVCodecParser cavsvideo_parser = {
 101     { CODEC_ID_CAVS },
 102     sizeof(ParseContext1),
 103     NULL,
 104     cavsvideo_parse,
 105     ff_parse1_close,
 106     ff_mpeg4video_split,
 107 };