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libavformat/aea.c

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00001 /*
00002  * MD STUDIO audio demuxer
00003  *
00004  * Copyright (c) 2009 Benjamin Larsson
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #include "avformat.h"
00024 #include "pcm.h"
00025 #include "libavutil/intreadwrite.h"
00026 #include "libavutil/audioconvert.h"
00027 
00028 #define AT1_SU_SIZE     212
00029 
00030 static int aea_read_probe(AVProbeData *p)
00031 {
00032     if (p->buf_size <= 2048+212)
00033         return 0;
00034 
00035     /* Magic is '00 08 00 00' in Little Endian*/
00036     if (AV_RL32(p->buf)==0x800) {
00037         int bsm_s, bsm_e, inb_s, inb_e, ch;
00038         ch    = p->buf[264];
00039         bsm_s = p->buf[2048];
00040         inb_s = p->buf[2048+1];
00041         inb_e = p->buf[2048+210];
00042         bsm_e = p->buf[2048+211];
00043 
00044         if (ch != 1 && ch != 2)
00045             return 0;
00046 
00047         /* Check so that the redundant bsm bytes and info bytes are valid
00048          * the block size mode bytes have to be the same
00049          * the info bytes have to be the same
00050          */
00051         if (bsm_s == bsm_e && inb_s == inb_e)
00052             return AVPROBE_SCORE_MAX / 4 + 1;
00053     }
00054     return 0;
00055 }
00056 
00057 static int aea_read_header(AVFormatContext *s,
00058                            AVFormatParameters *ap)
00059 {
00060     AVStream *st = av_new_stream(s, 0);
00061     if (!st)
00062         return AVERROR(ENOMEM);
00063 
00064     /* Parse the amount of channels and skip to pos 2048(0x800) */
00065     avio_skip(s->pb, 264);
00066     st->codec->channels = avio_r8(s->pb);
00067     avio_skip(s->pb, 1783);
00068 
00069 
00070     st->codec->codec_type     = AVMEDIA_TYPE_AUDIO;
00071     st->codec->codec_id       = CODEC_ID_ATRAC1;
00072     st->codec->sample_rate    = 44100;
00073     st->codec->bit_rate       = 292000;
00074 
00075     if (st->codec->channels != 1 && st->codec->channels != 2) {
00076         av_log(s,AV_LOG_ERROR,"Channels %d not supported!\n",st->codec->channels);
00077         return -1;
00078     }
00079 
00080     st->codec->channel_layout = (st->codec->channels == 1) ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;
00081 
00082     st->codec->block_align = AT1_SU_SIZE * st->codec->channels;
00083     return 0;
00084 }
00085 
00086 static int aea_read_packet(AVFormatContext *s, AVPacket *pkt)
00087 {
00088     int ret = av_get_packet(s->pb, pkt, s->streams[0]->codec->block_align);
00089 
00090     pkt->stream_index = 0;
00091     if (ret <= 0)
00092         return AVERROR(EIO);
00093 
00094     return ret;
00095 }
00096 
00097 AVInputFormat ff_aea_demuxer = {
00098     "aea",
00099     NULL_IF_CONFIG_SMALL("MD STUDIO audio"),
00100     0,
00101     aea_read_probe,
00102     aea_read_header,
00103     aea_read_packet,
00104     0,
00105     pcm_read_seek,
00106     .flags= AVFMT_GENERIC_INDEX,
00107     .extensions = "aea",
00108 };
00109 

Generated on Fri Feb 22 2013 07:24:31 for FFmpeg by  doxygen 1.7.1