FFmpeg
sccdec.c
Go to the documentation of this file.
1 /*
2  * SCC subtitle demuxer
3  * Copyright (c) 2017 Paul B Mahol
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 #include "avformat.h"
23 #include "internal.h"
24 #include "subtitles.h"
25 #include "libavutil/avstring.h"
26 #include "libavutil/bprint.h"
27 #include "libavutil/intreadwrite.h"
28 
29 typedef struct SCCContext {
30  FFDemuxSubtitlesQueue q;
31 } SCCContext;
32 
33 static int scc_probe(const AVProbeData *p)
34 {
35  char buf[18];
36  FFTextReader tr;
37 
38  ff_text_init_buf(&tr, p->buf, p->buf_size);
39 
40  while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')
41  ff_text_r8(&tr);
42 
43  ff_text_read(&tr, buf, sizeof(buf));
44 
45  if (!memcmp(buf, "Scenarist_SCC V1.0", 18))
46  return AVPROBE_SCORE_MAX;
47 
48  return 0;
49 }
50 
51 static int convert(uint8_t x)
52 {
53  if (x >= 'a')
54  x -= 'a' - 10;
55  else if (x >= 'A')
56  x -= 'A' - 10;
57  else
58  x -= '0';
59  return x;
60 }
61 
62 static int scc_read_header(AVFormatContext *s)
63 {
64  SCCContext *scc = s->priv_data;
65  AVStream *st = avformat_new_stream(s, NULL);
66  AVPacket *sub = NULL;
67  ptrdiff_t len;
68  uint8_t out[4096];
69  FFTextReader tr;
70 
71  ff_text_init_avio(s, &tr, s->pb);
72 
73  if (!st)
74  return AVERROR(ENOMEM);
75  avpriv_set_pts_info(st, 64, 1, 1000);
76  st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
77  st->codecpar->codec_id = AV_CODEC_ID_EIA_608;
78 
79  while (1) {
80  char *saveptr = NULL, *lline;
81  int hh, mm, ss, fs, i;
82  char line[4096];
83  int64_t pos, ts;
84 
85  pos = ff_text_pos(&tr);
86  len = ff_subtitles_read_line(&tr, line, sizeof(line));
87  if (len <= 13) {
88  if (ff_text_eof(&tr))
89  break;
90  continue;
91  }
92  if (av_sscanf(line, "%d:%d:%d%*[:;]%d", &hh, &mm, &ss, &fs) != 4)
93  continue;
94 
95  ts = (hh * 3600LL + mm * 60LL + ss) * 1000LL + fs * 33LL;
96  if (sub)
97  sub->duration = ts - sub->pts;
98 
99  lline = line;
100  lline += 12;
101 
102  for (i = 0; i < 4095; i += 3) {
103  char *ptr = av_strtok(lline, " ", &saveptr);
104  char c1, c2, c3, c4;
105  uint8_t o1, o2;
106 
107  if (!ptr)
108  break;
109 
110  if (av_sscanf(ptr, "%c%c%c%c", &c1, &c2, &c3, &c4) != 4)
111  break;
112  o1 = convert(c2) | (convert(c1) << 4);
113  o2 = convert(c4) | (convert(c3) << 4);
114 
115  lline = NULL;
116 
117  if (i > 12 && o1 == 0x94 && o2 == 0x20 && saveptr &&
118  (av_strncasecmp(saveptr, "942f", 4) && !av_strncasecmp(saveptr, "942c", 4))) {
119 
120  sub = ff_subtitles_queue_insert(&scc->q, out, i, 0);
121  if (!sub)
122  return AVERROR(ENOMEM);
123 
124  sub->pos = pos;
125  pos += i;
126  sub->pts = ts;
127  sub->duration = i * 11;
128  ts += sub->duration;
129  i = 0;
130  }
131 
132  out[i+0] = 0xfc;
133  out[i+1] = o1;
134  out[i+2] = o2;
135  }
136 
137  sub = ff_subtitles_queue_insert(&scc->q, out, i, 0);
138  if (!sub)
139  return AVERROR(ENOMEM);
140 
141  sub->pos = pos;
142  sub->pts = ts;
143  }
144 
145  ff_subtitles_queue_finalize(s, &scc->q);
146 
147  return 0;
148 }
149 
150 const AVInputFormat ff_scc_demuxer = {
151  .name = "scc",
152  .long_name = NULL_IF_CONFIG_SMALL("Scenarist Closed Captions"),
153  .priv_data_size = sizeof(SCCContext),
154  .flags_internal = FF_FMT_INIT_CLEANUP,
155  .read_probe = scc_probe,
156  .read_header = scc_read_header,
157  .extensions = "scc",
158  .read_packet = ff_subtitles_read_packet,
159  .read_seek2 = ff_subtitles_read_seek,
160  .read_close = ff_subtitles_read_close,
161 };
AV_CODEC_ID_EIA_608
@ AV_CODEC_ID_EIA_608
Definition: codec_id.h:554
AVMEDIA_TYPE_SUBTITLE
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
ff_subtitles_read_close
int ff_subtitles_read_close(AVFormatContext *s)
Definition: subtitles.c:329
ff_text_r8
int ff_text_r8(FFTextReader *r)
Return the next byte.
Definition: subtitles.c:63
FF_FMT_INIT_CLEANUP
#define FF_FMT_INIT_CLEANUP
For an AVInputFormat with this flag set read_close() needs to be called by the caller upon read_heade...
Definition: internal.h:47
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
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: options.c:243
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:58
out
FILE * out
Definition: movenc.c:54
sub
static float sub(float src0, float src1)
Definition: dnn_backend_native_layer_mathbinary.c:31
FFTextReader
Definition: subtitles.h:41
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:454
c1
static const uint64_t c1
Definition: murmur3.c:51
ff_subtitles_read_line
ptrdiff_t ff_subtitles_read_line(FFTextReader *tr, char *buf, size_t size)
Read a line of text.
Definition: subtitles.c:435
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:771
read_close
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:143
SCCContext
Definition: sccdec.c:29
ss
#define ss(width, name, subs,...)
Definition: cbs_vp9.c:260
scc_probe
static int scc_probe(const AVProbeData *p)
Definition: sccdec.c:33
AVInputFormat
Definition: avformat.h:546
ff_text_init_buf
void ff_text_init_buf(FFTextReader *r, void *buf, size_t size)
Similar to ff_text_init_avio(), but sets it up to read from a bounded buffer.
Definition: subtitles.c:52
ff_subtitles_read_packet
int ff_subtitles_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: subtitles.c:315
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_read_callback.c:41
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:256
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:551
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:453
av_strtok
char * av_strtok(char *s, const char *delim, char **saveptr)
Split the string into several tokens which can be accessed by successive calls to av_strtok().
Definition: avstring.c:179
scc_read_header
static int scc_read_header(AVFormatContext *s)
Definition: sccdec.c:62
AVFormatContext
Format I/O context.
Definition: avformat.h:1104
internal.h
ff_text_read
void ff_text_read(FFTextReader *r, char *buf, size_t size)
Read the given number of bytes (in UTF-8).
Definition: subtitles.c:84
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:861
av_sscanf
int av_sscanf(const char *string, const char *format,...)
See libc sscanf manual for more information.
Definition: avsscanf.c:962
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:545
NULL
#define NULL
Definition: coverity.c:32
fs
#define fs(width, name, subs,...)
Definition: cbs_vp9.c:258
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:109
ff_text_init_avio
void ff_text_init_avio(void *s, FFTextReader *r, AVIOContext *pb)
Initialize the FFTextReader from the given AVIOContext.
Definition: subtitles.c:26
ff_scc_demuxer
const AVInputFormat ff_scc_demuxer
Definition: sccdec.c:150
av_strncasecmp
int av_strncasecmp(const char *a, const char *b, size_t n)
Locale-independent case-insensitive compare.
Definition: avstring.c:218
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:115
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:196
FFDemuxSubtitlesQueue
Definition: subtitles.h:103
line
Definition: graph2dot.c:48
bprint.h
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
ff_text_pos
int64_t ff_text_pos(FFTextReader *r)
Return the byte position of the next byte returned by ff_text_r8().
Definition: subtitles.c:58
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:321
len
int len
Definition: vorbis_enc_data.h:426
AVStream
Stream structure.
Definition: avformat.h:838
pos
unsigned int pos
Definition: spdifenc.c:413
avformat.h
SCCContext::q
FFDemuxSubtitlesQueue q
Definition: sccdec.c:30
ff_text_peek_r8
int ff_text_peek_r8(FFTextReader *r)
Like ff_text_r8(), but don't remove the byte from the buffer.
Definition: subtitles.c:95
c2
static const uint64_t c2
Definition: murmur3.c:52
subtitles.h
read_probe
static int read_probe(const AVProbeData *p)
Definition: cdg.c:29
ff_text_eof
int ff_text_eof(FFTextReader *r)
Return non-zero if EOF was reached.
Definition: subtitles.c:90
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:62
AVPacket
This structure stores compressed data.
Definition: packet.h:351
convert
static int convert(uint8_t x)
Definition: sccdec.c:51
avstring.h
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
Generated on Tue Feb 28 2023 21:34:09 for FFmpeg by   doxygen 1.8.17