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/*
* 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 libavformat/mtv.c
* MTV demuxer.
*/
#include "libavutil/bswap.h"
#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 {
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 chanel (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;
return AVPROBE_SCORE_MAX;
}
static int mtv_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
MTVDemuxContext *mtv = s->priv_data;
ByteIOContext *pb = s->pb;
AVStream *st;
unsigned int audio_subsegments;
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);
url_fskip(pb, 4);
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;
// FIXME Add sanity check here
// all systems go! init decoders
// video - raw rgb565
st = av_new_stream(s, VIDEO_SID);
if(!st)
return AVERROR(ENOMEM);
av_set_pts_info(st, 64, 1, mtv->video_fps);
st->codec->codec_type = CODEC_TYPE_VIDEO;
st->codec->codec_id = CODEC_ID_RAWVIDEO;
st->codec->codec_tag = MKTAG('R', 'G', 'B', mtv->img_bpp);
st->codec->width = mtv->img_width;
st->codec->height = mtv->img_height;
st->codec->bits_per_coded_sample = mtv->img_bpp;
st->codec->sample_rate = mtv->video_fps;
// audio - mp3
st = av_new_stream(s, AUDIO_SID);
if(!st)
return AVERROR(ENOMEM);
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;
st->need_parsing = AVSTREAM_PARSE_FULL;
// Jump over header
if(url_fseek(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;
ByteIOContext *pb = s->pb;
int ret;
#ifndef WORDS_BIGENDIAN
int i;
#endif
ret = 0;
if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
{
url_fskip(pb, MTV_AUDIO_PADDING_SIZE);
ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);
if(ret != MTV_ASUBCHUNK_DATA_SIZE)
return AVERROR(EIO);
pkt->pos -= MTV_AUDIO_PADDING_SIZE;
pkt->stream_index = AUDIO_SID;
}else
{
ret = av_get_packet(pb, pkt, mtv->img_segment_size);
if(ret != mtv->img_segment_size)
return AVERROR(EIO);
#ifndef WORDS_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<mtv->img_segment_size/2;i++)
*((uint16_t *)pkt->data+i) = bswap_16(*((uint16_t *)pkt->data+i));
#endif
pkt->stream_index = VIDEO_SID;
}
return ret;
}
AVInputFormat mtv_demuxer = {
"MTV",
NULL_IF_CONFIG_SMALL("MTV format"),
sizeof(MTVDemuxContext),
mtv_probe,
mtv_read_header,
mtv_read_packet,
};
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