libavformat/aacdec.c

   1 /*
   2  * raw ADTS AAC demuxer
   3  * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
   4  * Copyright (c) 2009 Robert Swain ( rob opendot cl )
   5  *
   6  * This file is part of Libav.
   7  *
   8  * Libav 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  * Libav 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 Libav; 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/intreadwrite.h"
  24 #include "avformat.h"
  25 #include "internal.h"
  26 #include "rawdec.h"
  27 #include "id3v1.h"
  28
  29
  30 static int adts_aac_probe(AVProbeData *p)
  31 {
  32     int max_frames = 0, first_frames = 0;
  33     int fsize, frames;
  34     uint8_t *buf0 = p->buf;
  35     uint8_t *buf2;
  36     uint8_t *buf;
  37     uint8_t *end = buf0 + p->buf_size - 7;
  38
  39     buf = buf0;
  40
  41     for(; buf < end; buf= buf2+1) {
  42         buf2 = buf;
  43
  44         for(frames = 0; buf2 < end; frames++) {
  45             uint32_t header = AV_RB16(buf2);
  46             if((header&0xFFF6) != 0xFFF0)
  47                 break;
  48             fsize = (AV_RB32(buf2 + 3) >> 13) & 0x1FFF;
  49             if(fsize < 7)
  50                 break;
  51             buf2 += fsize;
  52         }
  53         max_frames = FFMAX(max_frames, frames);
  54         if(buf == buf0)
  55             first_frames= frames;
  56     }
  57     if   (first_frames>=3) return AVPROBE_SCORE_MAX/2+1;
  58     else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
  59     else if(max_frames>=3) return AVPROBE_SCORE_MAX/4;
  60     else if(max_frames>=1) return 1;
  61     else                   return 0;
  62 }
  63
  64 static int adts_aac_read_header(AVFormatContext *s)
  65 {
  66     AVStream *st;
  67
  68     st = avformat_new_stream(s, NULL);
  69     if (!st)
  70         return AVERROR(ENOMEM);
  71
  72     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
  73     st->codec->codec_id = s->iformat->raw_codec_id;
  74     st->need_parsing = AVSTREAM_PARSE_FULL;
  75
  76     ff_id3v1_read(s);
  77
  78     //LCM of all possible ADTS sample rates
  79     avpriv_set_pts_info(st, 64, 1, 28224000);
  80
  81     return 0;
  82 }
  83
  84 AVInputFormat ff_aac_demuxer = {
  85     .name           = "aac",
  86     .long_name      = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
  87     .read_probe     = adts_aac_probe,
  88     .read_header    = adts_aac_read_header,
  89     .read_packet    = ff_raw_read_partial_packet,
  90     .flags          = AVFMT_GENERIC_INDEX,
  91     .extensions     = "aac",
  92     .raw_codec_id   = AV_CODEC_ID_AAC,
  93 };