/*
  * mtv demuxer
  * Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
  *
  * 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
  */
 
 /**

  * @file libavformat/mtv.c

  * MTV demuxer.
  */
 

 #include "libavutil/bswap.h"

 #include "avformat.h"
 
 #define MTV_ASUBCHUNK_DATA_SIZE 500
 #define MTV_HEADER_SIZE 512
 #define MTV_AUDIO_PADDING_SIZE 12
 #define AUDIO_SAMPLING_RATE 44100
 #define VIDEO_SID 0
 #define AUDIO_SID 1
 
 typedef struct MTVDemuxContext {
 

     unsigned int file_size;         ///< filesize, not always right
     unsigned int segments;          ///< number of 512 byte segments
     unsigned int audio_identifier;  ///< 'MP3' on all files I have seen
     unsigned int audio_br;          ///< bitrate of audio chanel (mp3)
     unsigned int img_colorfmt;      ///< frame colorfmt rgb 565/555
     unsigned int img_bpp;           ///< frame bits per pixel
     unsigned int img_width;         //
     unsigned int img_height;        //
     unsigned int img_segment_size;  ///< size of image segment
     unsigned int video_fps;         //
     unsigned int full_segment_size;

 
 } MTVDemuxContext;
 
 static int mtv_probe(AVProbeData *p)
 {
     /* Magic is 'AMV' */
     if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V')
         return 0;
 
     return AVPROBE_SCORE_MAX;
 }
 
 static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
 {

     MTVDemuxContext *mtv = s->priv_data;
     ByteIOContext   *pb  = s->pb;
     AVStream        *st;
     unsigned int    audio_subsegments;

 
     url_fskip(pb, 3);
     mtv->file_size         = get_le32(pb);
     mtv->segments          = get_le32(pb);
     url_fskip(pb, 32);
     mtv->audio_identifier  = get_le24(pb);
     mtv->audio_br          = get_le16(pb);
     mtv->img_colorfmt      = get_le24(pb);
     mtv->img_bpp           = get_byte(pb);
     mtv->img_width         = get_le16(pb);
     mtv->img_height        = get_le16(pb);
     mtv->img_segment_size  = get_le16(pb);
     url_fskip(pb, 4);

     audio_subsegments = get_le16(pb);
     mtv->full_segment_size =
         audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
         mtv->img_segment_size;
     mtv->video_fps         = (mtv->audio_br / 4) / audio_subsegments;

     // FIXME Add sanity check here

     // all systems go! init decoders

     // video - raw rgb565

 
     st = av_new_stream(s, VIDEO_SID);
     if(!st)

         return AVERROR(ENOMEM);

 
     av_set_pts_info(st, 64, 1, mtv->video_fps);
     st->codec->codec_type      = CODEC_TYPE_VIDEO;
     st->codec->codec_id        = CODEC_ID_RAWVIDEO;

     st->codec->codec_tag       = MKTAG('R', 'G', 'B', mtv->img_bpp);

     st->codec->width           = mtv->img_width;
     st->codec->height          = mtv->img_height;

     st->codec->bits_per_coded_sample = mtv->img_bpp;

     st->codec->sample_rate     = mtv->video_fps;
 

     // audio - mp3

 
     st = av_new_stream(s, AUDIO_SID);
     if(!st)

         return AVERROR(ENOMEM);

 
     av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
     st->codec->codec_type      = CODEC_TYPE_AUDIO;
     st->codec->codec_id        = CODEC_ID_MP3;
     st->codec->bit_rate        = mtv->audio_br;

     st->need_parsing           = AVSTREAM_PARSE_FULL;

     // Jump over header

 
     if(url_fseek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)

         return AVERROR(EIO);

     return 0;

 
 }
 
 static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     MTVDemuxContext *mtv = s->priv_data;

     ByteIOContext *pb = s->pb;

     int ret;
 #ifndef WORDS_BIGENDIAN
     int i;
 #endif
 
     ret = 0;
 

     if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)

     {
         url_fskip(pb, MTV_AUDIO_PADDING_SIZE);
 
         ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
         if(ret != MTV_ASUBCHUNK_DATA_SIZE)

             return AVERROR(EIO);

         pkt->pos -= MTV_AUDIO_PADDING_SIZE;

         pkt->stream_index = AUDIO_SID;
 
     }else
     {
         ret = av_get_packet(pb, pkt, mtv->img_segment_size);
         if(ret != mtv->img_segment_size)

             return AVERROR(EIO);

 
 #ifndef WORDS_BIGENDIAN
 
         /* pkt->data is GGGRRRR BBBBBGGG
          * and we need RRRRRGGG GGGBBBBB
          * for PIX_FMT_RGB565 so here we
          * just swap bytes as they come
          */
 
         for(i=0;i<mtv->img_segment_size/2;i++)
             *((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i));
 #endif
         pkt->stream_index = VIDEO_SID;
     }
 

     return ret;

 }
 
 AVInputFormat mtv_demuxer = {
     "MTV",

     NULL_IF_CONFIG_SMALL("MTV format"),

     sizeof(MTVDemuxContext),
     mtv_probe,
     mtv_read_header,
     mtv_read_packet,
 };