FFmpeg
ttmlenc.c
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1 /*
2  * TTML subtitle muxer
3  * Copyright (c) 2020 24i
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  * TTML subtitle muxer
25  * @see https://www.w3.org/TR/ttml1/
26  * @see https://www.w3.org/TR/ttml2/
27  * @see https://www.w3.org/TR/ttml-imsc/rec
28  */
29 
30 #include "avformat.h"
31 #include "internal.h"
32 #include "libavcodec/ttmlenc.h"
33 #include "libavutil/internal.h"
34 
38 };
39 
41  const char *tt_element_params;
42  const char *pre_body_elements;
43 };
44 
45 typedef struct TTMLMuxContext {
47  unsigned int document_written;
49 
50 static const char ttml_header_text[] =
51 "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
52 "<tt\n"
53 "%s"
54 " xml:lang=\"%s\">\n"
55 "%s"
56 " <body>\n"
57 " <div>\n";
58 
59 static const char ttml_footer_text[] =
60 " </div>\n"
61 " </body>\n"
62 "</tt>\n";
63 
64 static void ttml_write_time(AVIOContext *pb, const char tag[],
65  int64_t millisec)
66 {
67  int64_t sec, min, hour;
68  sec = millisec / 1000;
69  millisec -= 1000 * sec;
70  min = sec / 60;
71  sec -= 60 * min;
72  hour = min / 60;
73  min -= 60 * hour;
74 
75  avio_printf(pb, "%s=\"%02"PRId64":%02"PRId64":%02"PRId64".%03"PRId64"\"",
76  tag, hour, min, sec, millisec);
77 }
78 
80  AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
81 {
82  size_t additional_data_size =
84  char *value =
86  size_t value_size = av_strnlen(value, additional_data_size);
87  struct TTMLHeaderParameters local_params = { 0 };
88 
89  if (!additional_data_size) {
90  // simple case, we don't have to go through local_params and just
91  // set default fall-back values (for old extradata format).
93  header_params->pre_body_elements = "";
94 
95  return 0;
96  }
97 
98  if (value_size == additional_data_size ||
99  value[value_size] != '\0')
100  return AVERROR_INVALIDDATA;
101 
102  local_params.tt_element_params = value;
103 
104  additional_data_size -= value_size + 1;
105  value += value_size + 1;
106  if (!additional_data_size)
107  return AVERROR_INVALIDDATA;
108 
109  value_size = av_strnlen(value, additional_data_size);
110  if (value_size == additional_data_size ||
111  value[value_size] != '\0')
112  return AVERROR_INVALIDDATA;
113 
114  local_params.pre_body_elements = value;
115 
116  *header_params = local_params;
117 
118  return 0;
119 }
120 
122 {
123  TTMLMuxContext *ttml_ctx = ctx->priv_data;
124  ttml_ctx->document_written = 0;
125 
126  if (ctx->nb_streams != 1 ||
128  av_log(ctx, AV_LOG_ERROR, "Exactly one TTML stream is required!\n");
129  return AVERROR(EINVAL);
130  }
131 
132  {
133  AVStream *st = ctx->streams[0];
134  AVIOContext *pb = ctx->pb;
135 
136  AVDictionaryEntry *lang = av_dict_get(st->metadata, "language", NULL,
137  0);
138  const char *printed_lang = (lang && lang->value) ? lang->value : "";
139 
140  // Not perfect, but decide whether the packet is a document or not
141  // by the existence of the lavc ttmlenc extradata.
142  ttml_ctx->input_type = (st->codecpar->extradata &&
144  !memcmp(st->codecpar->extradata,
149 
150  avpriv_set_pts_info(st, 64, 1, 1000);
151 
152  if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) {
153  struct TTMLHeaderParameters header_params;
155  st->codecpar, &header_params);
156  if (ret < 0) {
158  "Failed to parse TTML header values from extradata: "
159  "%s!\n", av_err2str(ret));
160  return ret;
161  }
162 
164  header_params.tt_element_params,
165  printed_lang,
166  header_params.pre_body_elements);
167  }
168  }
169 
170  return 0;
171 }
172 
174 {
175  TTMLMuxContext *ttml_ctx = ctx->priv_data;
176  AVIOContext *pb = ctx->pb;
177 
178  switch (ttml_ctx->input_type) {
180  // write out a paragraph element with the given contents.
181  avio_printf(pb, " <p\n");
182  ttml_write_time(pb, " begin", pkt->pts);
183  avio_w8(pb, '\n');
184  ttml_write_time(pb, " end", pkt->pts + pkt->duration);
185  avio_printf(pb, ">");
186  avio_write(pb, pkt->data, pkt->size);
187  avio_printf(pb, "</p>\n");
188  break;
190  // dump the given document out as-is.
191  if (ttml_ctx->document_written) {
193  "Attempting to write multiple TTML documents into a "
194  "single document! The XML specification forbids this "
195  "as there has to be a single root tag.\n");
196  return AVERROR(EINVAL);
197  }
198  avio_write(pb, pkt->data, pkt->size);
199  ttml_ctx->document_written = 1;
200  break;
201  default:
203  "Internal error: invalid TTML input packet type: %d!\n",
204  ttml_ctx->input_type);
205  return AVERROR_BUG;
206  }
207 
208  return 0;
209 }
210 
212 {
213  TTMLMuxContext *ttml_ctx = ctx->priv_data;
214  AVIOContext *pb = ctx->pb;
215 
216  if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH)
218 
219  return 0;
220 }
221 
223  .name = "ttml",
224  .long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"),
225  .extensions = "ttml",
226  .mime_type = "text/ttml",
227  .priv_data_size = sizeof(TTMLMuxContext),
230  .subtitle_codec = AV_CODEC_ID_TTML,
234 };
AVCodecParameters::extradata
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: codec_par.h:74
TTMLHeaderParameters
Definition: ttmlenc.c:40
AVOutputFormat::name
const char * name
Definition: avformat.h:491
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
ttml_write_trailer
static int ttml_write_trailer(AVFormatContext *ctx)
Definition: ttmlenc.c:211
AVCodecParameters
This struct describes the properties of an encoded stream.
Definition: codec_par.h:52
AVFMT_VARIABLE_FPS
#define AVFMT_VARIABLE_FPS
Format allows variable fps.
Definition: avformat.h:465
ttml_write_packet
static int ttml_write_packet(AVFormatContext *ctx, AVPacket *pkt)
Definition: ttmlenc.c:173
AVFormatContext::streams
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1174
AVPacket::data
uint8_t * data
Definition: packet.h:365
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:383
TTMLHeaderParameters::tt_element_params
const char * tt_element_params
Definition: ttmlenc.c:41
TTMLENC_EXTRADATA_SIGNATURE_SIZE
#define TTMLENC_EXTRADATA_SIGNATURE_SIZE
Definition: ttmlenc.h:26
PACKET_TYPE_PARAGRAPH
@ PACKET_TYPE_PARAGRAPH
Definition: ttmlenc.c:36
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
ttml_footer_text
static const char ttml_footer_text[]
Definition: ttmlenc.c:59
ttml_header_text
static const char ttml_header_text[]
Definition: ttmlenc.c:50
av_dict_get
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key.
Definition: dict.c:40
ttml_write_time
static void ttml_write_time(AVIOContext *pb, const char tag[], int64_t millisec)
Definition: ttmlenc.c:64
TTMLMuxContext
Definition: ttmlenc.c:45
TTMLPacketType
TTMLPacketType
Definition: ttmlenc.c:35
ctx
AVFormatContext * ctx
Definition: movenc.c:48
AVFormatContext
Format I/O context.
Definition: avformat.h:1106
ttml_write_header
static int ttml_write_header(AVFormatContext *ctx)
Definition: ttmlenc.c:121
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:979
TTMLHeaderParameters::pre_body_elements
const char * pre_body_elements
Definition: ttmlenc.c:42
NULL
#define NULL
Definition: coverity.c:32
write_trailer
static int write_trailer(AVFormatContext *s1)
Definition: v4l2enc.c:98
av_strnlen
size_t static size_t av_strnlen(const char *s, size_t len)
Get the count of continuous non zero chars starting from the beginning.
Definition: avstring.h:141
AVFormatContext::pb
AVIOContext * pb
I/O context.
Definition: avformat.h:1148
TTMLENC_EXTRADATA_SIGNATURE
#define TTMLENC_EXTRADATA_SIGNATURE
Definition: ttmlenc.h:25
TTMLMuxContext::input_type
enum TTMLPacketType input_type
Definition: ttmlenc.c:46
AVStream::metadata
AVDictionary * metadata
Definition: avformat.h:890
avio_w8
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:193
AVCodecParameters::extradata_size
int extradata_size
Size of the extradata content in bytes.
Definition: codec_par.h:78
AVFormatContext::nb_streams
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:1162
AVIOContext
Bytestream IO Context.
Definition: avio.h:161
AVPacket::size
int size
Definition: packet.h:366
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:117
TTMLMuxContext::document_written
unsigned int document_written
Definition: ttmlenc.c:47
av_err2str
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
avpriv_set_pts_info
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:4799
PACKET_TYPE_DOCUMENT
@ PACKET_TYPE_DOCUMENT
Definition: ttmlenc.c:37
avio_write
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:215
ttml_set_header_values_from_extradata
static int ttml_set_header_values_from_extradata(AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
Definition: ttmlenc.c:79
write_packet
static void write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost, int unqueue)
Definition: ffmpeg.c:729
AVFMT_GLOBALHEADER
#define AVFMT_GLOBALHEADER
Format wants global header.
Definition: avformat.h:461
AVOutputFormat
Definition: avformat.h:490
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:358
internal.h
ttmlenc.h
AV_CODEC_ID_TTML
@ AV_CODEC_ID_TTML
Definition: codec_id.h:543
value
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default value
Definition: writing_filters.txt:86
AVFMT_TS_NONSTRICT
#define AVFMT_TS_NONSTRICT
Format does not require strictly increasing timestamps, but they must still be monotonic.
Definition: avformat.h:472
tag
uint32_t tag
Definition: movenc.c:1594
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:832
ff_ttml_muxer
const AVOutputFormat ff_ttml_muxer
Definition: ttmlenc.c:222
avformat.h
avio_printf
int avio_printf(AVIOContext *s, const char *fmt,...) av_printf_format(2
Writes a formatted string to the context.
ttml_default_namespacing
static const char ttml_default_namespacing[]
Definition: ttmlenc.h:28
AVDictionaryEntry
Definition: dict.h:81
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
AVPacket
This structure stores compressed data.
Definition: packet.h:342
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
AVERROR_BUG
#define AVERROR_BUG
Internal bug, also see AVERROR_BUG2.
Definition: error.h:50
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
AVDictionaryEntry::value
char * value
Definition: dict.h:83
write_header
static void write_header(FFV1Context *f)
Definition: ffv1enc.c:346
AVFormatContext::priv_data
void * priv_data
Format private data.
Definition: avformat.h:1134
min
float min
Definition: vorbis_enc_data.h:429