libavcodec/aac_ac3_parser.c

   1 /*
   2  * Common AAC and AC3 parser
   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 #include "parser.h"
  24 #include "aac_ac3_parser.h"
  25
  26 int ff_aac_ac3_parse(AVCodecParserContext *s1,
  27                      AVCodecContext *avctx,
  28                      const uint8_t **poutbuf, int *poutbuf_size,
  29                      const uint8_t *buf, int buf_size)
  30 {
  31     AACAC3ParseContext *s = s1->priv_data;
  32     ParseContext *pc = &s->pc;
  33     int len, i;
  34     int new_frame_start;
  35
  36 get_next:
  37     i=END_NOT_FOUND;
  38     if(s->remaining_size <= buf_size){
  39         if(s->remaining_size && !s->need_next_header){
  40             i= s->remaining_size;
  41             s->remaining_size = 0;
  42         }else{ //we need a header first
  43             len=0;
  44             for(i=s->remaining_size; i<buf_size; i++){
  45                 s->state = (s->state<<8) + buf[i];
  46                 if((len=s->sync(s->state, s, &s->need_next_header, &new_frame_start)))
  47                     break;
  48             }
  49             if(len<=0){
  50                 i=END_NOT_FOUND;
  51             }else{
  52                 i-= s->header_size -1;
  53                 s->remaining_size = len;
  54                 if(!new_frame_start){
  55                     s->remaining_size += i;
  56                     goto get_next;
  57                 }
  58             }
  59         }
  60     }
  61
  62     if(ff_combine_frame(pc, i, &buf, &buf_size)<0){
  63         s->remaining_size -= FFMIN(s->remaining_size, buf_size);
  64         *poutbuf = NULL;
  65         *poutbuf_size = 0;
  66         return buf_size;
  67     }
  68
  69     *poutbuf = buf;
  70     *poutbuf_size = buf_size;
  71
  72     /* update codec info */
  73     avctx->sample_rate = s->sample_rate;
  74     /* allow downmixing to stereo (or mono for AC3) */
  75     if(avctx->request_channels > 0 &&
  76             avctx->request_channels < s->channels &&
  77             (avctx->request_channels <= 2 ||
  78             (avctx->request_channels == 1 &&
  79             avctx->codec_id == CODEC_ID_AC3))) {
  80         avctx->channels = avctx->request_channels;
  81     } else {
  82         avctx->channels = s->channels;
  83     }
  84     avctx->bit_rate = s->bit_rate;
  85     avctx->frame_size = s->samples;
  86
  87     return i;
  88 }