Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

218 lines (176 sloc) 6.599 kB
/*
* 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 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)
{
/* Magic is 'AMV' */
if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')
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_MAX/2;
else
return 0;
}
if(p->buf[51] != 16)
return AVPROBE_SCORE_MAX/4; // But we are going to assume 16bpp anyway ..
return AVPROBE_SCORE_MAX;
}
static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
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);
/* Calculate width and height if missing from header */
if(mtv->img_bpp>>3){
if(!mtv->img_width && mtv->img_height)
mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
/ mtv->img_height;
if(!mtv->img_height && mtv->img_width)
mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
/ mtv->img_width;
}
if(!mtv->img_height || !mtv->img_width){
av_log(s, AV_LOG_ERROR, "width or height is invalid and I cannot calculate them from other information\n");
return AVERROR(EINVAL);
}
avio_skip(pb, 4);
audio_subsegments = avio_rl16(pb);
if (audio_subsegments == 0) {
av_log_ask_for_sample(s, "MTV files without audio are not supported\n");
return AVERROR_INVALIDDATA;
}
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->codec->codec_type = AVMEDIA_TYPE_VIDEO;
st->codec->codec_id = CODEC_ID_RAWVIDEO;
st->codec->pix_fmt = PIX_FMT_RGB565;
st->codec->width = mtv->img_width;
st->codec->height = mtv->img_height;
st->codec->sample_rate = mtv->video_fps;
st->codec->extradata = av_strdup("BottomUp");
st->codec->extradata_size = 9;
// audio - mp3
st = avformat_new_stream(s, NULL);
if(!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);
st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
st->codec->codec_id = CODEC_ID_MP3;
st->codec->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 !HAVE_BIGENDIAN
int i;
#endif
if((avio_tell(pb) - s->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;
#if !HAVE_BIGENDIAN
/* 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<ret/2;i++)
*((uint16_t *)pkt->data+i) = av_bswap16(*((uint16_t *)pkt->data+i));
#endif
pkt->stream_index = 0;
}
return ret;
}
AVInputFormat ff_mtv_demuxer = {
.name = "MTV",
.long_name = NULL_IF_CONFIG_SMALL("MTV format"),
.priv_data_size = sizeof(MTVDemuxContext),
.read_probe = mtv_probe,
.read_header = mtv_read_header,
.read_packet = mtv_read_packet,
};
Jump to Line
Something went wrong with that request. Please try again.