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Member "ffmpeg-4.0.1/libavcodec/aac_ac3_parser.c" (20 Apr 2018, 3513 Bytes) of package /linux/misc/ffmpeg-4.0.1.tar.xz:


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    1 /*
    2  * Common AAC and AC-3 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 "libavutil/channel_layout.h"
   24 #include "libavutil/common.h"
   25 #include "parser.h"
   26 #include "aac_ac3_parser.h"
   27 
   28 int ff_aac_ac3_parse(AVCodecParserContext *s1,
   29                      AVCodecContext *avctx,
   30                      const uint8_t **poutbuf, int *poutbuf_size,
   31                      const uint8_t *buf, int buf_size)
   32 {
   33     AACAC3ParseContext *s = s1->priv_data;
   34     ParseContext *pc = &s->pc;
   35     int len, i;
   36     int new_frame_start;
   37     int got_frame = 0;
   38 
   39 get_next:
   40     i=END_NOT_FOUND;
   41     if(s->remaining_size <= buf_size){
   42         if(s->remaining_size && !s->need_next_header){
   43             i= s->remaining_size;
   44             s->remaining_size = 0;
   45         }else{ //we need a header first
   46             len=0;
   47             for(i=s->remaining_size; i<buf_size; i++){
   48                 s->state = (s->state<<8) + buf[i];
   49                 if((len=s->sync(s->state, s, &s->need_next_header, &new_frame_start)))
   50                     break;
   51             }
   52             if(len<=0){
   53                 i=END_NOT_FOUND;
   54             }else{
   55                 got_frame = 1;
   56                 s->state=0;
   57                 i-= s->header_size -1;
   58                 s->remaining_size = len;
   59                 if(!new_frame_start || pc->index+i<=0){
   60                     s->remaining_size += i;
   61                     goto get_next;
   62                 }
   63                 else if (i < 0) {
   64                     s->remaining_size += i;
   65                 }
   66             }
   67         }
   68     }
   69 
   70     if(ff_combine_frame(pc, i, &buf, &buf_size)<0){
   71         s->remaining_size -= FFMIN(s->remaining_size, buf_size);
   72         *poutbuf = NULL;
   73         *poutbuf_size = 0;
   74         return buf_size;
   75     }
   76 
   77     *poutbuf = buf;
   78     *poutbuf_size = buf_size;
   79 
   80     /* update codec info */
   81     if(s->codec_id)
   82         avctx->codec_id = s->codec_id;
   83 
   84     if (got_frame) {
   85         /* Due to backwards compatible HE-AAC the sample rate, channel count,
   86            and total number of samples found in an AAC ADTS header are not
   87            reliable. Bit rate is still accurate because the total frame
   88            duration in seconds is still correct (as is the number of bits in
   89            the frame). */
   90         if (avctx->codec_id != AV_CODEC_ID_AAC) {
   91             avctx->sample_rate = s->sample_rate;
   92             if (avctx->codec_id != AV_CODEC_ID_EAC3) {
   93                 avctx->channels = s->channels;
   94                 avctx->channel_layout = s->channel_layout;
   95             }
   96             s1->duration = s->samples;
   97             avctx->audio_service_type = s->service_type;
   98         }
   99 
  100         if (avctx->codec_id != AV_CODEC_ID_EAC3)
  101             avctx->bit_rate = s->bit_rate;
  102     }
  103 
  104     return i;
  105 }