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        audio_subsegments; ///< audio subsegments on one segment
  50
  51     uint8_t             audio_packet_count;
  52
  53 } MTVDemuxContext;
  54
  55 static int mtv_probe(AVProbeData *p)
  56 {
  57     /* Magic is 'AMV' */
  58
  59     if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V')
  60         return 0;
  61
  62     return AVPROBE_SCORE_MAX;
  63 }
  64
  65 static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
  66 {
  67     MTVDemuxContext    *mtv = s->priv_data;
  68     ByteIOContext      *pb  = s->pb;
  69     AVStream           *st;
  70
  71
  72     url_fskip(pb, 3);
  73     mtv->file_size         = get_le32(pb);
  74     mtv->segments          = get_le32(pb);
  75     url_fskip(pb, 32);
  76     mtv->audio_identifier  = get_le24(pb);
  77     mtv->audio_br          = get_le16(pb);
  78     mtv->img_colorfmt      = get_le24(pb);
  79     mtv->img_bpp           = get_byte(pb);
  80     mtv->img_width         = get_le16(pb);
  81     mtv->img_height        = get_le16(pb);
  82     mtv->img_segment_size  = get_le16(pb);
  83     url_fskip(pb, 4);
  84     mtv->audio_subsegments = get_le16(pb);
  85     mtv->video_fps         = (mtv->audio_br / 4) / mtv->audio_subsegments;
  86
  87     /* FIXME Add sanity check here */
  88
  89     /* first packet is always audio*/
  90
  91     mtv->audio_packet_count = 1;
  92
  93     /* all systems go! init decoders */
  94
  95     /* video - raw rgb565 */
  96
  97     st = av_new_stream(s, VIDEO_SID);
  98     if(!st)
  99         return AVERROR(ENOMEM);
 100
 101     av_set_pts_info(st, 64, 1, mtv->video_fps);
 102     st->codec->codec_type      = CODEC_TYPE_VIDEO;
 103     st->codec->codec_id        = CODEC_ID_RAWVIDEO;
 104     st->codec->codec_tag       = MKTAG('R', 'G', 'B', mtv->img_bpp);
 105     st->codec->width           = mtv->img_width;
 106     st->codec->height          = mtv->img_height;
 107     st->codec->bits_per_sample = mtv->img_bpp;
 108     st->codec->sample_rate     = mtv->video_fps;
 109
 110     /* audio - mp3 */
 111
 112     st = av_new_stream(s, AUDIO_SID);
 113     if(!st)
 114         return AVERROR(ENOMEM);
 115
 116     av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
 117     st->codec->codec_type      = CODEC_TYPE_AUDIO;
 118     st->codec->codec_id        = CODEC_ID_MP3;
 119     st->codec->bit_rate        = mtv->audio_br;
 120     st->need_parsing           = AVSTREAM_PARSE_FULL;
 121
 122     /* Jump over header */
 123
 124     if(url_fseek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
 125         return AVERROR(EIO);
 126
 127     return 0;
 128
 129 }
 130
 131 static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
 132 {
 133     MTVDemuxContext *mtv = s->priv_data;
 134     ByteIOContext *pb = s->pb;
 135     int ret;
 136 #ifndef WORDS_BIGENDIAN
 137     int i;
 138 #endif
 139
 140     ret = 0;
 141
 142     if(mtv->audio_subsegments >= mtv->audio_packet_count)
 143     {
 144         url_fskip(pb, MTV_AUDIO_PADDING_SIZE);
 145
 146         ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
 147         if(ret != MTV_ASUBCHUNK_DATA_SIZE)
 148             return AVERROR(EIO);
 149
 150         mtv->audio_packet_count++;
 151         pkt->stream_index = AUDIO_SID;
 152
 153     }else
 154     {
 155         ret = av_get_packet(pb, pkt, mtv->img_segment_size);
 156         if(ret != mtv->img_segment_size)
 157             return AVERROR(EIO);
 158
 159 #ifndef WORDS_BIGENDIAN
 160
 161         /* pkt->data is GGGRRRR BBBBBGGG
 162          * and we need RRRRRGGG GGGBBBBB
 163          * for PIX_FMT_RGB565 so here we
 164          * just swap bytes as they come
 165          */
 166
 167         for(i=0;i<mtv->img_segment_size/2;i++)
 168             *((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i));
 169 #endif
 170         mtv->audio_packet_count = 1;
 171         pkt->stream_index = VIDEO_SID;
 172     }
 173
 174     return ret;
 175 }
 176
 177 AVInputFormat mtv_demuxer = {
 178     "MTV",
 179     "MTV format",
 180     sizeof(MTVDemuxContext),
 181     mtv_probe,
 182     mtv_read_header,
 183     mtv_read_packet,
 184 };