/*
  * VAG demuxer
  * Copyright (c) 2015 Paul B Mahol
  *
  * 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 "avformat.h"
 #include "internal.h"
 

 static int vag_probe(const AVProbeData *p)

 {
     if (memcmp(p->buf, "VAGp\0\0\0", 7))
         return 0;
 
     return AVPROBE_SCORE_MAX;
 }
 
 static int vag_read_header(AVFormatContext *s)
 {
     AVStream *st;
 
     st = avformat_new_stream(s, NULL);
     if (!st)
         return AVERROR(ENOMEM);
 
     avio_skip(s->pb, 4);

     st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
     st->codecpar->codec_id    = AV_CODEC_ID_ADPCM_PSX;
     st->codecpar->channels    = 1 + (avio_rb32(s->pb) == 0x00000004);

     avio_skip(s->pb, 4);

     if (st->codecpar->channels > 1) {

         st->duration       = avio_rb32(s->pb);
     } else {
         st->duration       = avio_rb32(s->pb) / 16 * 28;
     }

     st->codecpar->sample_rate = avio_rb32(s->pb);
     if (st->codecpar->sample_rate <= 0)

         return AVERROR_INVALIDDATA;

     avio_seek(s->pb, 0x1000, SEEK_SET);
     if (avio_rl32(s->pb) == MKTAG('V','A','G','p')) {

         st->codecpar->block_align = 0x1000 * st->codecpar->channels;

         avio_seek(s->pb, 0, SEEK_SET);
         st->duration = st->duration / 16 * 28;
     } else {

         st->codecpar->block_align = 16 * st->codecpar->channels;
         avio_seek(s->pb, st->codecpar->channels > 1 ? 0x80 : 0x30, SEEK_SET);

     }

     avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);

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

     AVCodecParameters *par = s->streams[0]->codecpar;

     return av_get_packet(s->pb, pkt, par->block_align);

 }
 
 AVInputFormat ff_vag_demuxer = {
     .name           = "vag",

     .long_name      = NULL_IF_CONFIG_SMALL("Sony PS2 VAG"),

     .read_probe     = vag_probe,
     .read_header    = vag_read_header,
     .read_packet    = vag_read_packet,
     .extensions     = "vag",
 };