• Main Page
  • Related Pages
  • Modules
  • Data Structures
  • Files
  • File List
  • Globals

libavformat/aea.c

Go to the documentation of this file.
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 "raw.h"
00025 #include "libavutil/intreadwrite.h"
00026 
00027 #define AT1_SU_SIZE     212
00028 
00029 static int aea_read_probe(AVProbeData *p)
00030 {
00031     if (p->buf_size <= 2048+212)
00032         return 0;
00033 
00034     /* Magic is '00 08 00 00' in Little Endian*/
00035     if (AV_RL32(p->buf)==0x800) {
00036         int bsm_s, bsm_e, inb_s, inb_e, ch;
00037         ch    = p->buf[264];
00038         bsm_s = p->buf[2048];
00039         inb_s = p->buf[2048+1];
00040         inb_e = p->buf[2048+210];
00041         bsm_e = p->buf[2048+211];
00042 
00043         if (ch != 1 && ch != 2)
00044             return 0;
00045 
00046         /* Check so that the redundant bsm bytes and info bytes are valid
00047          * the block size mode bytes have to be the same
00048          * the info bytes have to be the same
00049          */
00050         if (bsm_s == bsm_e && inb_s == inb_e)
00051             return AVPROBE_SCORE_MAX / 4 + 1;
00052     }
00053     return 0;
00054 }
00055 
00056 static int aea_read_header(AVFormatContext *s,
00057                            AVFormatParameters *ap)
00058 {
00059     AVStream *st = av_new_stream(s, 0);
00060     if (!st)
00061         return AVERROR(ENOMEM);
00062 
00063     /* Parse the amount of channels and skip to pos 2048(0x800) */
00064     url_fskip(s->pb, 264);
00065     st->codec->channels = get_byte(s->pb);
00066     url_fskip(s->pb, 1783);
00067 
00068 
00069     st->codec->codec_type     = AVMEDIA_TYPE_AUDIO;
00070     st->codec->codec_id       = CODEC_ID_ATRAC1;
00071     st->codec->sample_rate    = 44100;
00072     st->codec->bit_rate       = 292000;
00073 
00074     if (st->codec->channels != 1 && st->codec->channels != 2) {
00075         av_log(s,AV_LOG_ERROR,"Channels %d not supported!\n",st->codec->channels);
00076         return -1;
00077     }
00078 
00079     st->codec->channel_layout = (st->codec->channels == 1) ? CH_LAYOUT_MONO : CH_LAYOUT_STEREO;
00080 
00081     st->codec->block_align = AT1_SU_SIZE * st->codec->channels;
00082     return 0;
00083 }
00084 
00085 static int aea_read_packet(AVFormatContext *s, AVPacket *pkt)
00086 {
00087     int ret = av_get_packet(s->pb, pkt, s->streams[0]->codec->block_align);
00088 
00089     pkt->stream_index = 0;
00090     if (ret <= 0)
00091         return AVERROR(EIO);
00092 
00093     return ret;
00094 }
00095 
00096 AVInputFormat aea_demuxer = {
00097     "aea",
00098     NULL_IF_CONFIG_SMALL("MD STUDIO audio"),
00099     0,
00100     aea_read_probe,
00101     aea_read_header,
00102     aea_read_packet,
00103     0,
00104     pcm_read_seek,
00105     .flags= AVFMT_GENERIC_INDEX,
00106     .extensions = "aea",
00107 };
00108 

Generated on Fri Sep 16 2011 17:17:47 for FFmpeg by  doxygen 1.7.1