FFmpeg
mtv.c
Go to the documentation of this file.
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
24  * MTV demuxer.
25  */
26 
27 #include "libavutil/intreadwrite.h"
28 #include "libavutil/mem.h"
29 #include "avformat.h"
30 #include "demux.h"
31 #include "internal.h"
32 
33 #define MTV_ASUBCHUNK_DATA_SIZE 500
34 #define MTV_HEADER_SIZE 512
35 #define MTV_AUDIO_PADDING_SIZE 12
36 #define MTV_IMAGE_DEFAULT_BPP 16
37 #define MTV_AUDIO_SAMPLING_RATE 44100
38 
39 typedef struct MTVDemuxContext {
40 
41  unsigned int file_size; ///< filesize, not always right
42  unsigned int segments; ///< number of 512 byte segments
43  unsigned int audio_identifier; ///< 'MP3' on all files I have seen
44  unsigned int audio_br; ///< bitrate of audio channel (mp3)
45  unsigned int img_colorfmt; ///< frame colorfmt rgb 565/555
46  unsigned int img_bpp; ///< frame bits per pixel
47  unsigned int img_width;
48  unsigned int img_height;
49  unsigned int img_segment_size; ///< size of image segment
50  unsigned int video_fps;
51  unsigned int full_segment_size;
52 
54 
55 static int mtv_probe(const AVProbeData *p)
56 {
57  /* we need at least 57 bytes from the header
58  * to try parsing all required fields
59  */
60  if (p->buf_size < 57)
61  return 0;
62 
63  /* Magic is 'AMV' */
64  if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')
65  return 0;
66 
67  /* Audio magic is always MP3 */
68  if (p->buf[43] != 'M' || p->buf[44] != 'P' || p->buf[45] != '3')
69  return 0;
70 
71  /* Check for nonzero in bpp and (width|height) header fields */
72  if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))
73  return 0;
74 
75  /* If width or height are 0 then imagesize header field should not */
76  if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))
77  {
78  if(!!AV_RL16(&p->buf[56]))
80  else
81  return 0;
82  }
83 
84  /* Image bpp is not an absolutely required
85  * field as we latter claim it should be 16
86  * no matter what. All samples in the wild
87  * are RGB565/555.
88  */
89  if(p->buf[51] != MTV_IMAGE_DEFAULT_BPP)
90  return AVPROBE_SCORE_EXTENSION / 2;
91 
92  /* We had enough data to parse header values
93  * but we expect to be able to get 512 bytes
94  * of header to be sure.
95  */
96  if (p->buf_size < MTV_HEADER_SIZE)
98 
99  return AVPROBE_SCORE_MAX;
100 }
101 
103 {
104  MTVDemuxContext *mtv = s->priv_data;
105  AVIOContext *pb = s->pb;
106  AVStream *st;
107  unsigned int audio_subsegments;
108 
109  avio_skip(pb, 3);
110  mtv->file_size = avio_rl32(pb);
111  mtv->segments = avio_rl32(pb);
112  avio_skip(pb, 32);
113  mtv->audio_identifier = avio_rl24(pb);
114  mtv->audio_br = avio_rl16(pb);
115  mtv->img_colorfmt = avio_rl24(pb);
116  mtv->img_bpp = avio_r8(pb);
117  mtv->img_width = avio_rl16(pb);
118  mtv->img_height = avio_rl16(pb);
119  mtv->img_segment_size = avio_rl16(pb);
120 
121  /* Assume 16bpp even if claimed otherwise.
122  * We know its going to be RGBG565/555 anyway
123  */
124  if (mtv->img_bpp != MTV_IMAGE_DEFAULT_BPP) {
125  av_log (s, AV_LOG_WARNING, "Header claims %dbpp (!= 16). Ignoring\n",
126  mtv->img_bpp);
128  }
129 
130  /* Calculate width and height if missing from header */
131 
132  if (!mtv->img_width && mtv->img_height > 0 && mtv->img_bpp >= 8)
133  mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)
134  / mtv->img_height;
135 
136  if (!mtv->img_height && mtv->img_width > 0 && mtv->img_bpp >= 8)
137  mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)
138  / mtv->img_width;
139 
140  if(!mtv->img_height || !mtv->img_width || !mtv->img_segment_size){
141  av_log(s, AV_LOG_ERROR, "width or height or segment_size is invalid and I cannot calculate them from other information\n");
142  return AVERROR_INVALIDDATA;
143  }
144 
145  avio_skip(pb, 4);
146  audio_subsegments = avio_rl16(pb);
147 
148  if (audio_subsegments == 0) {
149  avpriv_request_sample(s, "MTV files without audio");
150  return AVERROR_PATCHWELCOME;
151  }
152 
153  mtv->full_segment_size =
154  audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +
155  mtv->img_segment_size;
156  mtv->video_fps = (mtv->audio_br / 4) / audio_subsegments;
157 
158  // FIXME Add sanity check here
159 
160  // all systems go! init decoders
161 
162  // video - raw rgb565
163 
164  st = avformat_new_stream(s, NULL);
165  if(!st)
166  return AVERROR(ENOMEM);
167 
168  avpriv_set_pts_info(st, 64, 1, mtv->video_fps);
172  st->codecpar->width = mtv->img_width;
173  st->codecpar->height = mtv->img_height;
174  st->codecpar->extradata = av_strdup("BottomUp");
175  if (!st->codecpar->extradata)
176  return AVERROR(ENOMEM);
177  st->codecpar->extradata_size = 9;
178 
179  // audio - mp3
180 
181  st = avformat_new_stream(s, NULL);
182  if(!st)
183  return AVERROR(ENOMEM);
184 
188  st->codecpar->bit_rate = mtv->audio_br;
190 
191  // Jump over header
192 
193  if(avio_seek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)
194  return AVERROR(EIO);
195 
196  return 0;
197 
198 }
199 
201 {
202  MTVDemuxContext *mtv = s->priv_data;
203  AVIOContext *pb = s->pb;
204  int ret;
205 
206  if((avio_tell(pb) - ffformatcontext(s)->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
207  {
209 
211  if(ret < 0)
212  return ret;
213 
215  pkt->stream_index = 1;
216 
217  }else
218  {
219  ret = av_get_packet(pb, pkt, mtv->img_segment_size);
220  if(ret < 0)
221  return ret;
222 
223  pkt->stream_index = 0;
224  }
225 
226  return ret;
227 }
228 
230  .p.name = "mtv",
231  .p.long_name = NULL_IF_CONFIG_SMALL("MTV"),
232  .priv_data_size = sizeof(MTVDemuxContext),
236 };
MTVDemuxContext::file_size
unsigned int file_size
filesize, not always right
Definition: mtv.c:41
mtv_read_packet
static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mtv.c:200
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:186
AVCodecParameters::extradata
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: codec_par.h:69
MTVDemuxContext::full_segment_size
unsigned int full_segment_size
Definition: mtv.c:51
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:51
ffformatcontext
static av_always_inline FFFormatContext * ffformatcontext(AVFormatContext *s)
Definition: internal.h:188
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const struct AVCodec *c)
Add a new stream to a media file.
AV_CODEC_ID_RAWVIDEO
@ AV_CODEC_ID_RAWVIDEO
Definition: codec_id.h:65
MTV_HEADER_SIZE
#define MTV_HEADER_SIZE
Definition: mtv.c:34
mtv_probe
static int mtv_probe(const AVProbeData *p)
Definition: mtv.c:55
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:454
MTVDemuxContext::img_segment_size
unsigned int img_segment_size
size of image segment
Definition: mtv.c:49
MTVDemuxContext::img_height
unsigned int img_height
Definition: mtv.c:48
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:463
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: avformat.c:853
ffstream
static av_always_inline FFStream * ffstream(AVStream *st)
Definition: internal.h:417
MTV_IMAGE_DEFAULT_BPP
#define MTV_IMAGE_DEFAULT_BPP
Definition: mtv.c:36
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:494
AV_CODEC_ID_MP3
@ AV_CODEC_ID_MP3
preferred ID for decoding MPEG audio layer 1, 2 or 3
Definition: codec_id.h:441
avio_rl16
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:714
MTVDemuxContext::audio_br
unsigned int audio_br
bitrate of audio channel (mp3)
Definition: mtv.c:44
pkt
AVPacket * pkt
Definition: movenc.c:60
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_read_callback.c:42
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:553
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:453
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AVCodecParameters::width
int width
Video only.
Definition: codec_par.h:134
MTV_AUDIO_SAMPLING_RATE
#define MTV_AUDIO_SAMPLING_RATE
Definition: mtv.c:37
AV_RL16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:94
if
if(ret)
Definition: filter_design.txt:179
FFStream::need_parsing
enum AVStreamParseType need_parsing
Definition: internal.h:386
AVFormatContext
Format I/O context.
Definition: avformat.h:1255
ff_mtv_demuxer
const FFInputFormat ff_mtv_demuxer
Definition: mtv.c:229
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:766
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:550
NULL
#define NULL
Definition: coverity.c:32
mtv_read_header
static int mtv_read_header(AVFormatContext *s)
Definition: mtv.c:102
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:64
MTVDemuxContext::img_bpp
unsigned int img_bpp
frame bits per pixel
Definition: mtv.c:46
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
MTVDemuxContext::segments
unsigned int segments
number of 512 byte segments
Definition: mtv.c:42
MTVDemuxContext::video_fps
unsigned int video_fps
Definition: mtv.c:50
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:461
AVCodecParameters::extradata_size
int extradata_size
Size of the extradata content in bytes.
Definition: codec_par.h:73
avio_rl32
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:730
AVIOContext
Bytestream IO Context.
Definition: avio.h:160
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:94
MTV_AUDIO_PADDING_SIZE
#define MTV_AUDIO_PADDING_SIZE
Definition: mtv.c:35
FFInputFormat::p
AVInputFormat p
The public AVInputFormat.
Definition: demux.h:41
avio_r8
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:603
MTVDemuxContext::img_width
unsigned int img_width
Definition: mtv.c:47
MTV_ASUBCHUNK_DATA_SIZE
#define MTV_ASUBCHUNK_DATA_SIZE
Definition: mtv.c:33
avio_rl24
unsigned int avio_rl24(AVIOContext *s)
Definition: aviobuf.c:722
AVCodecParameters::height
int height
Definition: codec_par.h:135
demux.h
av_get_packet
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:91
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:743
avio_seek
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:231
avformat.h
MTVDemuxContext::img_colorfmt
unsigned int img_colorfmt
frame colorfmt rgb 565/555
Definition: mtv.c:45
AVPacket::stream_index
int stream_index
Definition: packet.h:526
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:318
AV_PIX_FMT_RGB565BE
@ AV_PIX_FMT_RGB565BE
packed RGB 5:6:5, 16bpp, (msb) 5R 6G 5B(lsb), big-endian
Definition: pixfmt.h:112
av_strdup
char * av_strdup(const char *s)
Duplicate a string.
Definition: mem.c:272
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
read_probe
static int read_probe(const AVProbeData *p)
Definition: cdg.c:30
mem.h
avpriv_request_sample
#define avpriv_request_sample(...)
Definition: tableprint_vlc.h:36
AVCodecParameters::format
int format
Definition: codec_par.h:92
MTVDemuxContext
Definition: mtv.c:39
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:55
AVPacket
This structure stores compressed data.
Definition: packet.h:501
AVPacket::pos
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:544
FFInputFormat
Definition: demux.h:37
AVSTREAM_PARSE_FULL
@ AVSTREAM_PARSE_FULL
full parsing and repack
Definition: avformat.h:593
AVCodecParameters::bit_rate
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:97
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
MTVDemuxContext::audio_identifier
unsigned int audio_identifier
'MP3' on all files I have seen
Definition: mtv.c:43