libavformat/mtv.c

   1 /*
   2  * mtv demuxer
   3  * Copyright (c) 2006 Reynaldo H. Verdejo Pinochet
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file mtv.c
  24  * MTV demuxer.
  25  */
  26
  27 #include "libavutil/bswap.h"
  28 #include "avformat.h"
  29
  30 #define MTV_ASUBCHUNK_DATA_SIZE 500
  31 #define MTV_HEADER_SIZE 512
  32 #define MTV_AUDIO_PADDING_SIZE 12
  33 #define AUDIO_SAMPLING_RATE 44100
  34 #define VIDEO_SID 0
  35 #define AUDIO_SID 1
  36
  37 typedef struct MTVDemuxContext {
  38
  39     unsigned int    file_size;         ///< filesize, not always right
  40     unsigned int    segments;          ///< number of 512 byte segments
  41     unsigned int    audio_identifier;  ///< 'MP3' on all files I have seen
  42     unsigned int    audio_br;          ///< bitrate of audio chanel (mp3)
  43     unsigned int    img_colorfmt;      ///< frame colorfmt rgb 565/555
  44     unsigned int    img_bpp;           ///< frame bits per pixel
  45     unsigned int    img_width;         //
  46     unsigned int    img_height;        //
  47     unsigned int    img_segment_size;  ///< size of image segment
  48     unsigned int    video_fps;         //
  49     unsigned int    full_segment_size;
  50
  51 } MTVDemuxContext;
  52
  53 static int mtv_probe(AVProbeData *p)
  54 {
  55     /* Magic is 'AMV' */
  56
  57     if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V')
  58         return 0;
  59
  60     return AVPROBE_SCORE_MAX;
  61 }
  62
  63 static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
  64 {
  65     MTVDemuxContext    *mtv = s->priv_data;
  66     ByteIOContext      *pb  = s->pb;
  67     AVStream           *st;
  68     unsigned int        audio_subsegments;
  69
  70
  71     url_fskip(pb, 3);
  72     mtv->file_size         = get_le32(pb);
  73     mtv->segments          = get_le32(pb);
  74     url_fskip(pb, 32);
  75     mtv->audio_identifier  = get_le24(pb);
  76     mtv->audio_br          = get_le16(pb);
  77     mtv->img_colorfmt      = get_le24(pb);
  78     mtv->img_bpp           = get_byte(pb);
  79     mtv->img_width         = get_le16(pb);
  80     mtv->img_height        = get_le16(pb);
  81     mtv->img_segment_size  = get_le16(pb);
  82     url_fskip(pb, 4);
  83     audio_subsegments = get_le16(pb);
  84     mtv->full_segment_size =
  85         audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
  86         mtv->img_segment_size;
  87     mtv->video_fps         = (mtv->audio_br / 4) / audio_subsegments;
  88
  89     // FIXME Add sanity check here
  90
  91     // all systems go! init decoders
  92
  93     // video - raw rgb565
  94
  95     st = av_new_stream(s, VIDEO_SID);
  96     if(!st)
  97         return AVERROR(ENOMEM);
  98
  99     av_set_pts_info(st, 64, 1, mtv->video_fps);
 100     st->codec->codec_type      = CODEC_TYPE_VIDEO;
 101     st->codec->codec_id        = CODEC_ID_RAWVIDEO;
 102     st->codec->codec_tag       = MKTAG('R', 'G', 'B', mtv->img_bpp);
 103     st->codec->width           = mtv->img_width;
 104     st->codec->height          = mtv->img_height;
 105     st->codec->bits_per_coded_sample = mtv->img_bpp;
 106     st->codec->sample_rate     = mtv->video_fps;
 107
 108     // audio - mp3
 109
 110     st = av_new_stream(s, AUDIO_SID);
 111     if(!st)
 112         return AVERROR(ENOMEM);
 113
 114     av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
 115     st->codec->codec_type      = CODEC_TYPE_AUDIO;
 116     st->codec->codec_id        = CODEC_ID_MP3;
 117     st->codec->bit_rate        = mtv->audio_br;
 118     st->need_parsing           = AVSTREAM_PARSE_FULL;
 119
 120     // Jump over header
 121
 122     if(url_fseek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
 123         return AVERROR(EIO);
 124
 125     return 0;
 126
 127 }
 128
 129 static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
 130 {
 131     MTVDemuxContext *mtv = s->priv_data;
 132     ByteIOContext *pb = s->pb;
 133     int ret;
 134 #ifndef WORDS_BIGENDIAN
 135     int i;
 136 #endif
 137
 138     ret = 0;
 139
 140     if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
 141     {
 142         url_fskip(pb, MTV_AUDIO_PADDING_SIZE);
 143
 144         ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
 145         if(ret != MTV_ASUBCHUNK_DATA_SIZE)
 146             return AVERROR(EIO);
 147
 148         pkt->pos -= MTV_AUDIO_PADDING_SIZE;
 149         pkt->stream_index = AUDIO_SID;
 150
 151     }else
 152     {
 153         ret = av_get_packet(pb, pkt, mtv->img_segment_size);
 154         if(ret != mtv->img_segment_size)
 155             return AVERROR(EIO);
 156
 157 #ifndef WORDS_BIGENDIAN
 158
 159         /* pkt->data is GGGRRRR BBBBBGGG
 160          * and we need RRRRRGGG GGGBBBBB
 161          * for PIX_FMT_RGB565 so here we
 162          * just swap bytes as they come
 163          */
 164
 165         for(i=0;i<mtv->img_segment_size/2;i++)
 166             *((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i));
 167 #endif
 168         pkt->stream_index = VIDEO_SID;
 169     }
 170
 171     return ret;
 172 }
 173
 174 AVInputFormat mtv_demuxer = {
 175     "MTV",
 176     NULL_IF_CONFIG_SMALL("MTV format"),
 177     sizeof(MTVDemuxContext),
 178     mtv_probe,
 179     mtv_read_header,
 180     mtv_read_packet,
 181 };