libavformat/aeadec.c

   1 /*
   2  * MD STUDIO audio demuxer
   3  *
   4  * Copyright (c) 2009 Benjamin Larsson
   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/intreadwrite.h"
  25 #include "avformat.h"
  26 #include "avio_internal.h"
  27 #include "demux.h"
  28 #include "internal.h"
  29 #include "pcm.h"
  30
  31 #define AT1_SU_SIZE 212
  32
  33 static int aea_read_probe(const AVProbeData *p)
  34 {
  35     if (p->buf_size <= 2048+AT1_SU_SIZE)
  36         return 0;
  37
  38     /* Magic is '00 08 00 00' in little-endian*/
  39     if (AV_RL32(p->buf)==0x800) {
  40         int ch, block_size, score = 0;
  41         ch = p->buf[264];
  42
  43         if (ch != 1 && ch != 2)
  44             return 0;
  45
  46         block_size = ch * AT1_SU_SIZE;
  47         /* Check so that the redundant bsm bytes and info bytes are valid
  48          * the block size mode bytes have to be the same
  49          * the info bytes have to be the same
  50          */
  51         for (int i = 2048 + block_size; i + block_size <= p->buf_size; i += block_size) {
  52             if (AV_RN16(p->buf+i) != AV_RN16(p->buf+i+AT1_SU_SIZE))
  53                 return 0;
  54             score++;
  55         }
  56         return FFMIN(AVPROBE_SCORE_MAX / 4 + score, AVPROBE_SCORE_MAX);
  57     }
  58     return 0;
  59 }
  60
  61 static int aea_read_header(AVFormatContext *s)
  62 {
  63     AVStream *st = avformat_new_stream(s, NULL);
  64     char title[256 + 1];
  65     int channels, ret;
  66     if (!st)
  67         return AVERROR(ENOMEM);
  68
  69     /* Read the title, parse the number of channels and skip to pos 2048(0x800) */
  70     avio_rl32(s->pb); // magic
  71     ret = ffio_read_size(s->pb, title, sizeof(title) - 1);
  72     if (ret < 0)
  73         return ret;
  74     title[sizeof(title) - 1] = '\0';
  75     if (title[0] != '\0')
  76         av_dict_set(&st->metadata, "title", title, 0);
  77     avio_rl32(s->pb); // Block count
  78     channels = avio_r8(s->pb);
  79     avio_skip(s->pb, 1783);
  80
  81
  82     st->codecpar->codec_type     = AVMEDIA_TYPE_AUDIO;
  83     st->codecpar->codec_id       = AV_CODEC_ID_ATRAC1;
  84     st->codecpar->sample_rate    = 44100;
  85     st->codecpar->bit_rate       = 146000 * channels;
  86
  87     if (channels < 1 || channels > 8) {
  88         av_log(s, AV_LOG_ERROR, "Channels %d not supported!\n", channels);
  89         return AVERROR_INVALIDDATA;
  90     }
  91
  92     av_channel_layout_default(&st->codecpar->ch_layout, channels);
  93
  94     st->codecpar->block_align = AT1_SU_SIZE * st->codecpar->ch_layout.nb_channels;
  95     avpriv_set_pts_info(st, 64, 1, 44100);
  96     return 0;
  97 }
  98
  99 static int aea_read_packet(AVFormatContext *s, AVPacket *pkt)
 100 {
 101     return av_get_packet(s->pb, pkt, s->streams[0]->codecpar->block_align);
 102 }
 103
 104 const FFInputFormat ff_aea_demuxer = {
 105     .p.name         = "aea",
 106     .p.long_name    = NULL_IF_CONFIG_SMALL("MD STUDIO audio"),
 107     .p.flags        = AVFMT_GENERIC_INDEX,
 108     .p.extensions   = "aea",
 109     .read_probe     = aea_read_probe,
 110     .read_header    = aea_read_header,
 111     .read_packet    = aea_read_packet,
 112     .read_seek      = ff_pcm_read_seek,
 113 };