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 libavformat/mtv.c
  24  * MTV demuxer.
  25  */
  26
  27 #include "libavutil/bswap.h"
  28 #include "libavutil/intreadwrite.h"
  29 #include "avformat.h"
  30
  31 #define MTV_ASUBCHUNK_DATA_SIZE 500
  32 #define MTV_HEADER_SIZE 512
  33 #define MTV_AUDIO_PADDING_SIZE 12
  34 #define AUDIO_SAMPLING_RATE 44100
  35 #define VIDEO_SID 0
  36 #define AUDIO_SID 1
  37
  38 typedef struct MTVDemuxContext {
  39
  40     unsigned int file_size;         ///< filesize, not always right
  41     unsigned int segments;          ///< number of 512 byte segments
  42     unsigned int audio_identifier;  ///< 'MP3' on all files I have seen
  43     unsigned int audio_br;          ///< bitrate of audio channel (mp3)
  44     unsigned int img_colorfmt;      ///< frame colorfmt rgb 565/555
  45     unsigned int img_bpp;           ///< frame bits per pixel
  46     unsigned int img_width;         //
  47     unsigned int img_height;        //
  48     unsigned int img_segment_size;  ///< size of image segment
  49     unsigned int video_fps;         //
  50     unsigned int full_segment_size;
  51
  52 } MTVDemuxContext;
  53
  54 static int mtv_probe(AVProbeData *p)
  55 {
  56     /* Magic is 'AMV' */
  57     if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V')
  58         return 0;
  59
  60     /* Check for nonzero in bpp and (width|height) header fields */
  61     if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))
  62         return 0;
  63
  64     /* If width or height are 0 then imagesize header field should not */
  65     if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))
  66     {
  67         if(!!AV_RL16(&p->buf[56]))
  68             return AVPROBE_SCORE_MAX/2;
  69         else
  70             return 0;
  71     }
  72
  73     if(p->buf[51] != 16)
  74         return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway ..
  75
  76     return AVPROBE_SCORE_MAX;
  77 }
  78
  79 static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
  80 {
  81     MTVDemuxContext *mtv = s->priv_data;
  82     ByteIOContext   *pb  = s->pb;
  83     AVStream        *st;
  84     unsigned int    audio_subsegments;
  85
  86     url_fskip(pb, 3);
  87     mtv->file_size         = get_le32(pb);
  88     mtv->segments          = get_le32(pb);
  89     url_fskip(pb, 32);
  90     mtv->audio_identifier  = get_le24(pb);
  91     mtv->audio_br          = get_le16(pb);
  92     mtv->img_colorfmt      = get_le24(pb);
  93     mtv->img_bpp           = get_byte(pb);
  94     mtv->img_width         = get_le16(pb);
  95     mtv->img_height        = get_le16(pb);
  96     mtv->img_segment_size  = get_le16(pb);
  97
  98     /* Calculate width and height if missing from header */
  99
 100     if(!mtv->img_width)
 101         mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
 102                         / mtv->img_height;
 103
 104     if(!mtv->img_height)
 105         mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
 106                         / mtv->img_width;
 107
 108     url_fskip(pb, 4);
 109     audio_subsegments = get_le16(pb);
 110     mtv->full_segment_size =
 111         audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
 112         mtv->img_segment_size;
 113     mtv->video_fps         = (mtv->audio_br / 4) / audio_subsegments;
 114
 115     // FIXME Add sanity check here
 116
 117     // all systems go! init decoders
 118
 119     // video - raw rgb565
 120
 121     st = av_new_stream(s, VIDEO_SID);
 122     if(!st)
 123         return AVERROR(ENOMEM);
 124
 125     av_set_pts_info(st, 64, 1, mtv->video_fps);
 126     st->codec->codec_type      = CODEC_TYPE_VIDEO;
 127     st->codec->codec_id        = CODEC_ID_RAWVIDEO;
 128     st->codec->codec_tag       = MKTAG('R', 'G', 'B', mtv->img_bpp);
 129     st->codec->width           = mtv->img_width;
 130     st->codec->height          = mtv->img_height;
 131     st->codec->bits_per_coded_sample = mtv->img_bpp;
 132     st->codec->sample_rate     = mtv->video_fps;
 133     st->codec->extradata       = av_strdup("BottomUp");
 134     st->codec->extradata_size  = 9;
 135
 136     // audio - mp3
 137
 138     st = av_new_stream(s, AUDIO_SID);
 139     if(!st)
 140         return AVERROR(ENOMEM);
 141
 142     av_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
 143     st->codec->codec_type      = CODEC_TYPE_AUDIO;
 144     st->codec->codec_id        = CODEC_ID_MP3;
 145     st->codec->bit_rate        = mtv->audio_br;
 146     st->need_parsing           = AVSTREAM_PARSE_FULL;
 147
 148     // Jump over header
 149
 150     if(url_fseek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
 151         return AVERROR(EIO);
 152
 153     return 0;
 154
 155 }
 156
 157 static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
 158 {
 159     MTVDemuxContext *mtv = s->priv_data;
 160     ByteIOContext *pb = s->pb;
 161     int ret;
 162 #if !HAVE_BIGENDIAN
 163     int i;
 164 #endif
 165
 166     if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
 167     {
 168         url_fskip(pb, MTV_AUDIO_PADDING_SIZE);
 169
 170         ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
 171         if(ret != MTV_ASUBCHUNK_DATA_SIZE)
 172             return AVERROR(EIO);
 173
 174         pkt->pos -= MTV_AUDIO_PADDING_SIZE;
 175         pkt->stream_index = AUDIO_SID;
 176
 177     }else
 178     {
 179         ret = av_get_packet(pb, pkt, mtv->img_segment_size);
 180         if(ret != mtv->img_segment_size)
 181             return AVERROR(EIO);
 182
 183 #if !HAVE_BIGENDIAN
 184
 185         /* pkt->data is GGGRRRR BBBBBGGG
 186          * and we need RRRRRGGG GGGBBBBB
 187          * for PIX_FMT_RGB565 so here we
 188          * just swap bytes as they come
 189          */
 190
 191         for(i=0;i<mtv->img_segment_size/2;i++)
 192             *((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i));
 193 #endif
 194         pkt->stream_index = VIDEO_SID;
 195     }
 196
 197     return ret;
 198 }
 199
 200 AVInputFormat mtv_demuxer = {
 201     "MTV",
 202     NULL_IF_CONFIG_SMALL("MTV format"),
 203     sizeof(MTVDemuxContext),
 204     mtv_probe,
 205     mtv_read_header,
 206     mtv_read_packet,
 207 };