/*
  * 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

  * MTV demuxer.
  */
 

 #include "libavutil/bswap.h"

 #include "libavutil/intreadwrite.h"

 #include "avformat.h"

 #include "internal.h"

 
 #define MTV_ASUBCHUNK_DATA_SIZE 500
 #define MTV_HEADER_SIZE 512
 #define MTV_AUDIO_PADDING_SIZE 12

 #define MTV_IMAGE_DEFAULT_BPP 16

 #define MTV_AUDIO_SAMPLING_RATE 44100

 
 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 channel (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)
 {

     /* we need at least 57 bytes from the header
      * to try parsing all required fields
      */
     if (p->buf_size < 57)
         return 0;
 

     /* Magic is 'AMV' */

     if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')

         return 0;
 

     /* Audio magic is always MP3 */
     if (p->buf[43] != 'M' || p->buf[44] != 'P' || p->buf[45] != '3')
         return 0;
 

     /* Check for nonzero in bpp and (width|height) header fields */

     if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))

         return 0;
 

     /* If width or height are 0 then imagesize header field should not */

     if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))

     {
         if(!!AV_RL16(&p->buf[56]))

             return AVPROBE_SCORE_EXTENSION;

         else
             return 0;
     }
 

     /* Image bpp is not an absolutely required
      * field as we latter claim it should be 16
      * no matter what. All samples in the wild
      * are RGB565/555.
      */
     if(p->buf[51] != MTV_IMAGE_DEFAULT_BPP)
         return AVPROBE_SCORE_EXTENSION / 2;

     /* We had enough data to parse header values
      * but we expect to be able to get 512 bytes
      * of header to be sure.
      */
     if (p->buf_size < MTV_HEADER_SIZE)
         return AVPROBE_SCORE_EXTENSION;
 

     return AVPROBE_SCORE_MAX;
 }
 

 static int mtv_read_header(AVFormatContext *s)

 {

     MTVDemuxContext *mtv = s->priv_data;

     AVIOContext   *pb  = s->pb;

     AVStream        *st;
     unsigned int    audio_subsegments;

     avio_skip(pb, 3);

     mtv->file_size         = avio_rl32(pb);
     mtv->segments          = avio_rl32(pb);

     avio_skip(pb, 32);

     mtv->audio_identifier  = avio_rl24(pb);
     mtv->audio_br          = avio_rl16(pb);
     mtv->img_colorfmt      = avio_rl24(pb);
     mtv->img_bpp           = avio_r8(pb);
     mtv->img_width         = avio_rl16(pb);
     mtv->img_height        = avio_rl16(pb);
     mtv->img_segment_size  = avio_rl16(pb);

     /* Assume 16bpp even if claimed otherwise.
      * We know its going to be RGBG565/555 anyway
      */
     if (mtv->img_bpp != MTV_IMAGE_DEFAULT_BPP) {
         av_log (s, AV_LOG_WARNING, "Header claims %dbpp (!= 16). Ignoring\n",
                 mtv->img_bpp);
         mtv->img_bpp = MTV_IMAGE_DEFAULT_BPP;
     }
 

     /* Calculate width and height if missing from header */
 

     if (!mtv->img_width && mtv->img_height > 0 && mtv->img_bpp >= 8)

         mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
                         / mtv->img_height;
 

     if (!mtv->img_height && mtv->img_width > 0 && mtv->img_bpp >= 8)

         mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
                         / mtv->img_width;

     if(!mtv->img_height || !mtv->img_width || !mtv->img_segment_size){
         av_log(s, AV_LOG_ERROR, "width or height or segment_size is invalid and I cannot calculate them from other information\n");

         return AVERROR_INVALIDDATA;

     }

     avio_skip(pb, 4);

     audio_subsegments = avio_rl16(pb);

 
     if (audio_subsegments == 0) {

         avpriv_request_sample(s, "MTV files without audio");

         return AVERROR_PATCHWELCOME;

     }

     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 = avformat_new_stream(s, NULL);

     if(!st)

         return AVERROR(ENOMEM);

     avpriv_set_pts_info(st, 64, 1, mtv->video_fps);

     st->codecpar->codec_type      = AVMEDIA_TYPE_VIDEO;
     st->codecpar->codec_id        = AV_CODEC_ID_RAWVIDEO;
     st->codecpar->format          = AV_PIX_FMT_RGB565BE;
     st->codecpar->width           = mtv->img_width;
     st->codecpar->height          = mtv->img_height;
     st->codecpar->extradata       = av_strdup("BottomUp");
     st->codecpar->extradata_size  = 9;

     // audio - mp3

     st = avformat_new_stream(s, NULL);

     if(!st)

         return AVERROR(ENOMEM);

     avpriv_set_pts_info(st, 64, 1, MTV_AUDIO_SAMPLING_RATE);

     st->codecpar->codec_type      = AVMEDIA_TYPE_AUDIO;
     st->codecpar->codec_id        = AV_CODEC_ID_MP3;
     st->codecpar->bit_rate        = mtv->audio_br;
     st->need_parsing              = AVSTREAM_PARSE_FULL;

     // Jump over header

     if(avio_seek(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;

     AVIOContext *pb = s->pb;

     int ret;
 

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

     {

         avio_skip(pb, MTV_AUDIO_PADDING_SIZE);

 
         ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);

         if(ret < 0)
             return ret;

         pkt->pos -= MTV_AUDIO_PADDING_SIZE;

         pkt->stream_index = 1;

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

         if(ret < 0)
             return ret;

         pkt->stream_index = 0;

     }
 

     return ret;

 }
 

 AVInputFormat ff_mtv_demuxer = {

     .name           = "mtv",

     .long_name      = NULL_IF_CONFIG_SMALL("MTV"),

     .priv_data_size = sizeof(MTVDemuxContext),
     .read_probe     = mtv_probe,
     .read_header    = mtv_read_header,
     .read_packet    = mtv_read_packet,

 };