FFmpeg
mpl2dec.c
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1 /*
2  * Copyright (c) 2012 Clément Bœsch
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * MPL2 subtitles format demuxer
24  */
25 
26 #include "libavutil/intreadwrite.h"
27 
28 #include "avformat.h"
29 #include "demux.h"
30 #include "internal.h"
31 #include "subtitles.h"
32 
33 typedef struct {
35 } MPL2Context;
36 
37 static int mpl2_probe(const AVProbeData *p)
38 {
39  int i;
40  char c;
41  int64_t start, end;
42  const unsigned char *ptr = p->buf;
43  const unsigned char *ptr_end = ptr + p->buf_size;
44 
45  if (AV_RB24(ptr) == 0xefbbbf)
46  ptr += 3;
47 
48  for (i = 0; i < 2; i++) {
49  if (sscanf(ptr, "[%"SCNd64"][%"SCNd64"]%c", &start, &end, &c) != 3 &&
50  sscanf(ptr, "[%"SCNd64"][]%c", &start, &c) != 2)
51  return 0;
52  ptr += ff_subtitles_next_line(ptr);
53  if (ptr >= ptr_end)
54  return 0;
55  }
56  return AVPROBE_SCORE_MAX;
57 }
58 
59 static int read_ts(char **line, int64_t *pts_start, int64_t *duration)
60 {
61  char c;
62  int len;
63  int64_t end;
64 
65  if (sscanf(*line, "[%"SCNd64"][]%c%n",
66  pts_start, &c, &len) >= 2) {
67  *duration = -1;
68  *line += len - 1;
69  return 0;
70  }
71  if (sscanf(*line, "[%"SCNd64"][%"SCNd64"]%c%n",
72  pts_start, &end, &c, &len) >= 3) {
73  if (end < *pts_start || end - (uint64_t)*pts_start > INT64_MAX) {
74  *duration = -1;
75  } else
76  *duration = end - *pts_start;
77  *line += len - 1;
78  return 0;
79  }
80  return -1;
81 }
82 
84 {
85  MPL2Context *mpl2 = s->priv_data;
87 
88  if (!st)
89  return AVERROR(ENOMEM);
90  avpriv_set_pts_info(st, 64, 1, 10);
93 
94  if (avio_rb24(s->pb) != 0xefbbbf)
95  avio_seek(s->pb, -3, SEEK_CUR);
96 
97  while (!avio_feof(s->pb)) {
98  char line[4096];
99  char *p = line;
100  const int64_t pos = avio_tell(s->pb);
101  int len = ff_get_line(s->pb, line, sizeof(line));
102  int64_t pts_start;
103  int64_t duration;
104 
105  if (!len)
106  break;
107 
108  line[strcspn(line, "\r\n")] = 0;
109 
110  if (!read_ts(&p, &pts_start, &duration)) {
111  AVPacket *sub;
112 
113  sub = ff_subtitles_queue_insert(&mpl2->q, p, strlen(p), 0);
114  if (!sub)
115  return AVERROR(ENOMEM);
116  sub->pos = pos;
117  sub->pts = pts_start;
118  sub->duration = duration;
119  }
120  }
121 
123  return 0;
124 }
125 
127  .p.name = "mpl2",
128  .p.long_name = NULL_IF_CONFIG_SMALL("MPL2 subtitles"),
129  .p.extensions = "txt,mpl2",
130  .priv_data_size = sizeof(MPL2Context),
131  .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
135  .read_seek2 = ff_subtitles_read_seek,
137 };
AVMEDIA_TYPE_SUBTITLE
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
ff_subtitles_read_close
int ff_subtitles_read_close(AVFormatContext *s)
Definition: subtitles.c:345
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
mpl2_probe
static int mpl2_probe(const AVProbeData *p)
Definition: mpl2dec.c:37
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const struct AVCodec *c)
Add a new stream to a media file.
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:538
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:454
mpl2_read_header
static int mpl2_read_header(AVFormatContext *s)
Definition: mpl2dec.c:83
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
AV_CODEC_ID_MPL2
@ AV_CODEC_ID_MPL2
Definition: codec_id.h:569
read_close
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:143
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:494
ff_subtitles_read_packet
int ff_subtitles_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: subtitles.c:331
duration
int64_t duration
Definition: movenc.c:65
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
FF_INFMT_FLAG_INIT_CLEANUP
#define FF_INFMT_FLAG_INIT_CLEANUP
For an FFInputFormat with this flag set read_close() needs to be called by the caller upon read_heade...
Definition: demux.h:35
AVFormatContext
Format I/O context.
Definition: avformat.h:1255
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:766
MPL2Context::q
FFDemuxSubtitlesQueue q
Definition: mpl2dec.c:34
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:550
NULL
#define NULL
Definition: coverity.c:32
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
ff_subtitles_queue_insert
AVPacket * ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q, const uint8_t *event, size_t len, int merge)
Insert a new subtitle event.
Definition: subtitles.c:111
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
avio_rb24
unsigned int avio_rb24(AVIOContext *s)
Definition: aviobuf.c:754
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
ff_subtitles_queue_finalize
void ff_subtitles_queue_finalize(void *log_ctx, FFDemuxSubtitlesQueue *q)
Set missing durations, sort subtitles by PTS (and then byte position), and drop duplicated events.
Definition: subtitles.c:212
FFDemuxSubtitlesQueue
Definition: subtitles.h:103
FFInputFormat::p
AVInputFormat p
The public AVInputFormat.
Definition: demux.h:41
line
Definition: graph2dot.c:48
read_ts
static int read_ts(char **line, int64_t *pts_start, int64_t *duration)
Definition: mpl2dec.c:59
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:513
ff_subtitles_read_seek
int ff_subtitles_read_seek(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
Definition: subtitles.c:337
ff_get_line
int ff_get_line(AVIOContext *s, char *buf, int maxlen)
Read a whole line of text from AVIOContext.
Definition: aviobuf.c:769
demux.h
len
int len
Definition: vorbis_enc_data.h:426
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
pos
unsigned int pos
Definition: spdifenc.c:414
avformat.h
subtitles.h
read_probe
static int read_probe(const AVProbeData *p)
Definition: cdg.c:30
MPL2Context
Definition: mpl2dec.c:33
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:497
AVPacket::pos
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:540
FFInputFormat
Definition: demux.h:37
ff_subtitles_next_line
static av_always_inline int ff_subtitles_next_line(const char *ptr)
Get the number of characters to increment to jump to the next line, or to the end of the string.
Definition: subtitles.h:205
AV_RB24
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_RB24
Definition: bytestream.h:97
line
The official guide to swscale for confused that consecutive non overlapping rectangles of slice_bottom special converter These generally are unscaled converters of common like for each output line the vertical scaler pulls lines from a ring buffer When the ring buffer does not contain the wanted line
Definition: swscale.txt:40
ff_mpl2_demuxer
const FFInputFormat ff_mpl2_demuxer
Definition: mpl2dec.c:126
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:346