/*
  * AST demuxer
  * Copyright (c) 2012 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 "libavutil/intreadwrite.h"
 #include "avformat.h"
 #include "internal.h"

 #include "ast.h"

 static int ast_probe(const AVProbeData *p)

 {

     if (AV_RL32(p->buf) != MKTAG('S','T','R','M'))
         return 0;
 
     if (!AV_RB16(p->buf + 10) ||
         !AV_RB16(p->buf + 12) || AV_RB16(p->buf + 12) > 256 ||
         !AV_RB32(p->buf + 16) || AV_RB32(p->buf + 16) > 8*48000)

         return AVPROBE_SCORE_MAX / 8;

 
     return AVPROBE_SCORE_MAX / 3 * 2;

 }
 
 static int ast_read_header(AVFormatContext *s)
 {

     int depth;

     AVStream *st;
 
     st = avformat_new_stream(s, NULL);
     if (!st)
         return AVERROR(ENOMEM);
 
     avio_skip(s->pb, 8);

     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
     st->codecpar->codec_id   = ff_codec_get_id(ff_codec_ast_tags, avio_rb16(s->pb));

     depth = avio_rb16(s->pb);
     if (depth != 16) {

         avpriv_request_sample(s, "depth %d", depth);

         return AVERROR_INVALIDDATA;
     }

     st->codecpar->channels = avio_rb16(s->pb);
     if (!st->codecpar->channels)

         return AVERROR_INVALIDDATA;
 

     if (st->codecpar->channels == 2)
         st->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;
     else if (st->codecpar->channels == 4)
         st->codecpar->channel_layout = AV_CH_LAYOUT_4POINT0;

 
     avio_skip(s->pb, 2);

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

         return AVERROR_INVALIDDATA;
     st->start_time         = 0;
     st->duration           = avio_rb32(s->pb);
     avio_skip(s->pb, 40);

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

 
     return 0;
 }
 
 static int ast_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     uint32_t type, size;
     int64_t pos;
     int ret;
 

     if (avio_feof(s->pb))

         return AVERROR_EOF;
 
     pos  = avio_tell(s->pb);
     type = avio_rl32(s->pb);
     size = avio_rb32(s->pb);

     if (!s->streams[0]->codecpar->channels || size > INT_MAX / s->streams[0]->codecpar->channels)

         return AVERROR_INVALIDDATA;
 

     size *= s->streams[0]->codecpar->channels;

     if ((ret = avio_skip(s->pb, 24)) < 0) // padding
         return ret;
 
     if (type == MKTAG('B','L','C','K')) {
         ret = av_get_packet(s->pb, pkt, size);
         pkt->stream_index = 0;
         pkt->pos = pos;
     } else {

         av_log(s, AV_LOG_ERROR, "unknown chunk %"PRIx32"\n", type);

         avio_skip(s->pb, size);
         ret = AVERROR_INVALIDDATA;
     }
 
     return ret;
 }
 
 AVInputFormat ff_ast_demuxer = {
     .name           = "ast",
     .long_name      = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),
     .read_probe     = ast_probe,
     .read_header    = ast_read_header,
     .read_packet    = ast_read_packet,
     .extensions     = "ast",
     .flags          = AVFMT_GENERIC_INDEX,

     .codec_tag      = (const AVCodecTag* const []){ff_codec_ast_tags, 0},

 };