FFmpeg/libavformat/mtv.c

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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
* 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 MTV_IMAGE_DEFAULT_BPP 16
#define MTV_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(const AVProbeData *p)
{
/* we need at least 57 bytes from the header
* to try parsing all required fields
*/
if (p->buf_size < 57)
return 0;
/* Magic is 'AMV' */
if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')
return 0;
/* Audio magic is always MP3 */
if (p->buf[43] != 'M' || p->buf[44] != 'P' || p->buf[45] != '3')
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_EXTENSION;
else
return 0;
}
/* Image bpp is not an absolutely required
* field as we latter claim it should be 16
* no matter what. All samples in the wild
* are RGB565/555.
*/
if(p->buf[51] != MTV_IMAGE_DEFAULT_BPP)
return AVPROBE_SCORE_EXTENSION / 2;
/* We had enough data to parse header values
* but we expect to be able to get 512 bytes
* of header to be sure.
*/
if (p->buf_size < MTV_HEADER_SIZE)
return AVPROBE_SCORE_EXTENSION;
return AVPROBE_SCORE_MAX;
}
static int mtv_read_header(AVFormatContext *s)
{
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);
/* Assume 16bpp even if claimed otherwise.
* We know its going to be RGBG565/555 anyway
*/
if (mtv->img_bpp != MTV_IMAGE_DEFAULT_BPP) {
av_log (s, AV_LOG_WARNING, "Header claims %dbpp (!= 16). Ignoring\n",
mtv->img_bpp);
mtv->img_bpp = MTV_IMAGE_DEFAULT_BPP;
}
/* Calculate width and height if missing from header */
if (!mtv->img_width && mtv->img_height > 0 && mtv->img_bpp >= 8)
mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
/ mtv->img_height;
if (!mtv->img_height && mtv->img_width > 0 && mtv->img_bpp >= 8)
mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
/ mtv->img_width;
if(!mtv->img_height || !mtv->img_width || !mtv->img_segment_size){
av_log(s, AV_LOG_ERROR, "width or height or segment_size is invalid and I cannot calculate them from other information\n");
return AVERROR_INVALIDDATA;
}
avio_skip(pb, 4);
audio_subsegments = avio_rl16(pb);
if (audio_subsegments == 0) {
avpriv_request_sample(s, "MTV files without audio");
return AVERROR_PATCHWELCOME;
}
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);
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 18:42:52 +00:00
st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
st->codecpar->codec_id = AV_CODEC_ID_RAWVIDEO;
st->codecpar->format = AV_PIX_FMT_RGB565BE;
st->codecpar->width = mtv->img_width;
st->codecpar->height = mtv->img_height;
st->codecpar->extradata = av_strdup("BottomUp");
if (!st->codecpar->extradata)
return AVERROR(ENOMEM);
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 18:42:52 +00:00
st->codecpar->extradata_size = 9;
// audio - mp3
st = avformat_new_stream(s, NULL);
if(!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, MTV_AUDIO_SAMPLING_RATE);
lavf: replace AVStream.codec with AVStream.codecpar Currently, AVStream contains an embedded AVCodecContext instance, which is used by demuxers to export stream parameters to the caller and by muxers to receive stream parameters from the caller. It is also used internally as the codec context that is passed to parsers. In addition, it is also widely used by the callers as the decoding (when demuxer) or encoding (when muxing) context, though this has been officially discouraged since Libav 11. There are multiple important problems with this approach: - the fields in AVCodecContext are in general one of * stream parameters * codec options * codec state However, it's not clear which ones are which. It is consequently unclear which fields are a demuxer allowed to set or a muxer allowed to read. This leads to erratic behaviour depending on whether decoding or encoding is being performed or not (and whether it uses the AVStream embedded codec context). - various synchronization issues arising from the fact that the same context is used by several different APIs (muxers/demuxers, parsers, bitstream filters and encoders/decoders) simultaneously, with there being no clear rules for who can modify what and the different processes being typically delayed with respect to each other. - avformat_find_stream_info() making it necessary to support opening and closing a single codec context multiple times, thus complicating the semantics of freeing various allocated objects in the codec context. Those problems are resolved by replacing the AVStream embedded codec context with a newly added AVCodecParameters instance, which stores only the stream parameters exported by the demuxers or read by the muxers.
2014-06-18 18:42:52 +00:00
st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
st->codecpar->codec_id = AV_CODEC_ID_MP3;
st->codecpar->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((avio_tell(pb) - s->internal->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;
pkt->stream_index = 0;
}
return ret;
}
AVInputFormat ff_mtv_demuxer = {
.name = "mtv",
.long_name = NULL_IF_CONFIG_SMALL("MTV"),
.priv_data_size = sizeof(MTVDemuxContext),
.read_probe = mtv_probe,
.read_header = mtv_read_header,
.read_packet = mtv_read_packet,
};