FFmpeg
mpl2dec.c
Go to the documentation of this file.
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 "internal.h"
30 #include "subtitles.h"
31 
32 typedef struct {
34 } MPL2Context;
35 
36 static int mpl2_probe(const AVProbeData *p)
37 {
38  int i;
39  char c;
40  int64_t start, end;
41  const unsigned char *ptr = p->buf;
42  const unsigned char *ptr_end = ptr + p->buf_size;
43 
44  if (AV_RB24(ptr) == 0xefbbbf)
45  ptr += 3;
46 
47  for (i = 0; i < 2; i++) {
48  if (sscanf(ptr, "[%"SCNd64"][%"SCNd64"]%c", &start, &end, &c) != 3 &&
49  sscanf(ptr, "[%"SCNd64"][]%c", &start, &c) != 2)
50  return 0;
51  ptr += ff_subtitles_next_line(ptr);
52  if (ptr >= ptr_end)
53  return 0;
54  }
55  return AVPROBE_SCORE_MAX;
56 }
57 
58 static int read_ts(char **line, int64_t *pts_start, int64_t *duration)
59 {
60  char c;
61  int len;
62  int64_t end;
63 
64  if (sscanf(*line, "[%"SCNd64"][]%c%n",
65  pts_start, &c, &len) >= 2) {
66  *duration = -1;
67  *line += len - 1;
68  return 0;
69  }
70  if (sscanf(*line, "[%"SCNd64"][%"SCNd64"]%c%n",
71  pts_start, &end, &c, &len) >= 3) {
72  if (end < *pts_start || end - (uint64_t)*pts_start > INT64_MAX) {
73  *duration = -1;
74  } else
75  *duration = end - *pts_start;
76  *line += len - 1;
77  return 0;
78  }
79  return -1;
80 }
81 
83 {
84  MPL2Context *mpl2 = s->priv_data;
86 
87  if (!st)
88  return AVERROR(ENOMEM);
89  avpriv_set_pts_info(st, 64, 1, 10);
92 
93  if (avio_rb24(s->pb) != 0xefbbbf)
94  avio_seek(s->pb, -3, SEEK_CUR);
95 
96  while (!avio_feof(s->pb)) {
97  char line[4096];
98  char *p = line;
99  const int64_t pos = avio_tell(s->pb);
100  int len = ff_get_line(s->pb, line, sizeof(line));
101  int64_t pts_start;
102  int64_t duration;
103 
104  if (!len)
105  break;
106 
107  line[strcspn(line, "\r\n")] = 0;
108 
109  if (!read_ts(&p, &pts_start, &duration)) {
110  AVPacket *sub;
111 
112  sub = ff_subtitles_queue_insert(&mpl2->q, p, strlen(p), 0);
113  if (!sub) {
114  ff_subtitles_queue_clean(&mpl2->q);
115  return AVERROR(ENOMEM);
116  }
117  sub->pos = pos;
118  sub->pts = pts_start;
119  sub->duration = duration;
120  }
121  }
122 
123  ff_subtitles_queue_finalize(s, &mpl2->q);
124  return 0;
125 }
126 
128 {
129  MPL2Context *mpl2 = s->priv_data;
130  return ff_subtitles_queue_read_packet(&mpl2->q, pkt);
131 }
132 
133 static int mpl2_read_seek(AVFormatContext *s, int stream_index,
134  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
135 {
136  MPL2Context *mpl2 = s->priv_data;
137  return ff_subtitles_queue_seek(&mpl2->q, s, stream_index,
138  min_ts, ts, max_ts, flags);
139 }
140 
142 {
143  MPL2Context *mpl2 = s->priv_data;
144  ff_subtitles_queue_clean(&mpl2->q);
145  return 0;
146 }
147 
149  .name = "mpl2",
150  .long_name = NULL_IF_CONFIG_SMALL("MPL2 subtitles"),
151  .priv_data_size = sizeof(MPL2Context),
155  .read_seek2 = mpl2_read_seek,
157  .extensions = "txt,mpl2",
158 };
#define NULL
Definition: coverity.c:32
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:383
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4869
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:253
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:302
static AVPacket pkt
Format I/O context.
Definition: avformat.h:1351
int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
Generic read_packet() callback for subtitles demuxers using this queue system.
Definition: subtitles.c:212
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:92
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:381
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
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4450
int64_t duration
Definition: movenc.c:63
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:145
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
AVInputFormat ff_mpl2_demuxer
Definition: mpl2dec.c:148
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:153
unsigned int pos
Definition: spdifenc.c:410
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
Definition: graph2dot.c:48
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:444
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
unsigned int avio_rb24(AVIOContext *s)
Definition: aviobuf.c:783
#define s(width, name)
Definition: cbs_vp9.c:257
int ff_get_line(AVIOContext *s, char *buf, int maxlen)
Read a whole line of text from AVIOContext.
Definition: aviobuf.c:798
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:527
static int mpl2_read_header(AVFormatContext *s)
Definition: mpl2dec.c:82
static int read_ts(char **line, int64_t *pts_start, int64_t *duration)
Definition: mpl2dec.c:58
Stream structure.
Definition: avformat.h:876
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
Update current_sub_idx to emulate a seek.
Definition: subtitles.c:250
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:87
AVIOContext * pb
I/O context.
Definition: avformat.h:1393
FFDemuxSubtitlesQueue q
Definition: mpl2dec.c:33
static int mpl2_probe(const AVProbeData *p)
Definition: mpl2dec.c:36
static int mpl2_read_close(AVFormatContext *s)
Definition: mpl2dec.c:141
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
static int mpl2_read_seek(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
Definition: mpl2dec.c:133
#define flags(name, subs,...)
Definition: cbs_av1.c:560
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:187
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
Main libavformat public API header.
static int mpl2_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mpl2dec.c:127
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:33
int len
void * priv_data
Format private data.
Definition: avformat.h:1379
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:650
static float sub(float src0, float src1)
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1023
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:368
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
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
This structure stores compressed data.
Definition: packet.h:340
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:194
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:356
int i
Definition: input.c:407