mtv.c 6.1 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
/*
 * 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
 */

/**
23
 * @file libavformat/mtv.c
24 25 26
 * MTV demuxer.
 */

27
#include "libavutil/bswap.h"
28
#include "libavutil/intreadwrite.h"
29 30 31 32 33 34 35 36 37 38 39
#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 {

Reynaldo H. Verdejo Pinochet's avatar
Reynaldo H. Verdejo Pinochet committed
40 41 42
    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
43
    unsigned int audio_br;          ///< bitrate of audio channel (mp3)
Reynaldo H. Verdejo Pinochet's avatar
Reynaldo H. Verdejo Pinochet committed
44 45 46 47 48 49 50
    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;
51 52 53 54 55 56 57 58 59

} MTVDemuxContext;

static int mtv_probe(AVProbeData *p)
{
    /* Magic is 'AMV' */
    if(*(p->buf) != 'A' || *(p->buf+1) != 'M' || *(p->buf+2) != 'V')
        return 0;

60 61 62 63
    /* 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;

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 68 69 70 71 72
    {
        if(!!AV_RL16(&p->buf[56]))
            return AVPROBE_SCORE_MAX/2;
        else
            return 0;
    }

73
    if(p->buf[51] != 16)
74
        return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway ..
75

76 77 78 79 80
    return AVPROBE_SCORE_MAX;
}

static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
Reynaldo H. Verdejo Pinochet's avatar
Reynaldo H. Verdejo Pinochet committed
81 82 83 84
    MTVDemuxContext *mtv = s->priv_data;
    ByteIOContext   *pb  = s->pb;
    AVStream        *st;
    unsigned int    audio_subsegments;
85 86 87 88 89 90 91 92 93 94 95 96

    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);
97 98 99 100 101 102 103 104 105 106 107

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

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

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

108
    url_fskip(pb, 4);
109 110 111 112 113
    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;
114

115
    // FIXME Add sanity check here
116

117
    // all systems go! init decoders
118

119
    // video - raw rgb565
120 121 122

    st = av_new_stream(s, VIDEO_SID);
    if(!st)
123
        return AVERROR(ENOMEM);
124 125 126 127

    av_set_pts_info(st, 64, 1, mtv->video_fps);
    st->codec->codec_type      = CODEC_TYPE_VIDEO;
    st->codec->codec_id        = CODEC_ID_RAWVIDEO;
128
    st->codec->codec_tag       = MKTAG('R', 'G', 'B', mtv->img_bpp);
129 130
    st->codec->width           = mtv->img_width;
    st->codec->height          = mtv->img_height;
131
    st->codec->bits_per_coded_sample = mtv->img_bpp;
132
    st->codec->sample_rate     = mtv->video_fps;
133 134
    st->codec->extradata       = av_strdup("BottomUp");
    st->codec->extradata_size  = 9;
135

136
    // audio - mp3
137 138 139

    st = av_new_stream(s, AUDIO_SID);
    if(!st)
140
        return AVERROR(ENOMEM);
141 142 143 144 145

    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;
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;
154 155 156 157 158 159

}

static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    MTVDemuxContext *mtv = s->priv_data;
160
    ByteIOContext *pb = s->pb;
161
    int ret;
162
#if !HAVE_BIGENDIAN
163 164 165
    int i;
#endif

166
    if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
167 168 169 170 171
    {
        url_fskip(pb, MTV_AUDIO_PADDING_SIZE);

        ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
        if(ret != MTV_ASUBCHUNK_DATA_SIZE)
172
            return AVERROR(EIO);
173

174
        pkt->pos -= MTV_AUDIO_PADDING_SIZE;
175 176 177 178 179 180
        pkt->stream_index = AUDIO_SID;

    }else
    {
        ret = av_get_packet(pb, pkt, mtv->img_segment_size);
        if(ret != mtv->img_segment_size)
181
            return AVERROR(EIO);
182

183
#if !HAVE_BIGENDIAN
184 185 186 187 188 189 190 191 192 193 194 195 196

        /* 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;
    }

197
    return ret;
198 199 200 201
}

AVInputFormat mtv_demuxer = {
    "MTV",
202
    NULL_IF_CONFIG_SMALL("MTV format"),
203 204 205 206 207
    sizeof(MTVDemuxContext),
    mtv_probe,
    mtv_read_header,
    mtv_read_packet,
};