/*
  * MD STUDIO audio demuxer
  *
  * Copyright (c) 2009 Benjamin Larsson
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 #include "libavutil/channel_layout.h"
 #include "libavutil/intreadwrite.h"

 #include "avformat.h"

 #include "pcm.h"

 
 #define AT1_SU_SIZE     212
 
 static int aea_read_probe(AVProbeData *p)
 {
     if (p->buf_size <= 2048+212)
         return 0;
 

     /* Magic is '00 08 00 00' in little-endian*/

     if (AV_RL32(p->buf)==0x800) {

         int ch, i;
         ch = p->buf[264];

         if (ch != 1 && ch != 2)
             return 0;

 
         /* Check so that the redundant bsm bytes and info bytes are valid
          * the block size mode bytes have to be the same
          * the info bytes have to be the same
          */

         for (i = 2048; i + 211 < p->buf_size; i+= 212) {
             int bsm_s, bsm_e, inb_s, inb_e;
             bsm_s = p->buf[0];
             inb_s = p->buf[1];
             inb_e = p->buf[210];
             bsm_e = p->buf[211];
 
             if (bsm_s != bsm_e || inb_s != inb_e)
                 return 0;
         }
         return AVPROBE_SCORE_MAX / 4 + 1;

     }
     return 0;
 }
 

 static int aea_read_header(AVFormatContext *s)

 {

     AVStream *st = avformat_new_stream(s, NULL);

     if (!st)
         return AVERROR(ENOMEM);
 
     /* Parse the amount of channels and skip to pos 2048(0x800) */

     avio_skip(s->pb, 264);

     st->codecpar->channels = avio_r8(s->pb);

     avio_skip(s->pb, 1783);

     st->codecpar->codec_type     = AVMEDIA_TYPE_AUDIO;
     st->codecpar->codec_id       = AV_CODEC_ID_ATRAC1;
     st->codecpar->sample_rate    = 44100;
     st->codecpar->bit_rate       = 292000;

     if (st->codecpar->channels != 1 && st->codecpar->channels != 2) {
         av_log(s, AV_LOG_ERROR, "Channels %d not supported!\n", st->codecpar->channels);

         return AVERROR_INVALIDDATA;

     }
 

     st->codecpar->channel_layout = (st->codecpar->channels == 1) ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;

     st->codecpar->block_align = AT1_SU_SIZE * st->codecpar->channels;

     return 0;
 }
 
 static int aea_read_packet(AVFormatContext *s, AVPacket *pkt)
 {

     int ret = av_get_packet(s->pb, pkt, s->streams[0]->codecpar->block_align);

 
     pkt->stream_index = 0;
     if (ret <= 0)
         return AVERROR(EIO);
 
     return ret;
 }
 

 AVInputFormat ff_aea_demuxer = {

     .name           = "aea",
     .long_name      = NULL_IF_CONFIG_SMALL("MD STUDIO audio"),
     .read_probe     = aea_read_probe,
     .read_header    = aea_read_header,
     .read_packet    = aea_read_packet,

     .read_seek      = ff_pcm_read_seek,

     .flags          = AVFMT_GENERIC_INDEX,
     .extensions     = "aea",

 };