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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 "libavutil/avstring.h"
31#include "avformat.h"
32#include "internal.h"
33#include "mux.h"
34#include "ttmlenc.h"
35#include "libavcodec/ttmlenc.h"
36#include "libavutil/internal.h"
37
42
43struct TTMLHeaderParameters {
44 const char *tt_element_params;
45 const char *pre_body_elements;
46};
47
52
53static const char ttml_header_text[] =
54"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
55"<tt\n"
56"%s"
57" xml:lang=\"%s\">\n"
58"%s"
59" <body>\n"
60" <div>\n";
61
62static const char ttml_footer_text[] =
63" </div>\n"
64" </body>\n"
65"</tt>\n";
66
67static void ttml_write_time(AVIOContext *pb, const char tag[],
68 int64_t millisec)
69{
70 int64_t sec, min, hour;
71 sec = millisec / 1000;
72 millisec -= 1000 * sec;
73 min = sec / 60;
74 sec -= 60 * min;
75 hour = min / 60;
76 min -= 60 * hour;
77
78 avio_printf(pb, "%s=\"%02"PRId64":%02"PRId64":%02"PRId64".%03"PRId64"\"",
79 tag, hour, min, sec, millisec);
80}
81
82static int ttml_set_header_values_from_extradata(
83 AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
84{
85 size_t additional_data_size =
86 par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE;
87 char *value =
88 (char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE;
89 size_t value_size = av_strnlen(value, additional_data_size);
90 struct TTMLHeaderParameters local_params = { 0 };
91
92 if (!additional_data_size) {
93 // simple case, we don't have to go through local_params and just
94 // set default fall-back values (for old extradata format).
95 header_params->tt_element_params = TTML_DEFAULT_NAMESPACING;
96 header_params->pre_body_elements = "";
97
98 return 0;
99 }
100
101 if (value_size == additional_data_size ||
102 value[value_size] != '\0')
103 return AVERROR_INVALIDDATA;
104
105 local_params.tt_element_params = value;
106
107 additional_data_size -= value_size + 1;
108 value += value_size + 1;
109 if (!additional_data_size)
110 return AVERROR_INVALIDDATA;
111
112 value_size = av_strnlen(value, additional_data_size);
113 if (value_size == additional_data_size ||
114 value[value_size] != '\0')
115 return AVERROR_INVALIDDATA;
116
117 local_params.pre_body_elements = value;
118
119 *header_params = local_params;
120
121 return 0;
122}
123
124static int ttml_write_header(AVFormatContext *ctx)
125{
126 TTMLMuxContext *ttml_ctx = ctx->priv_data;
127 AVStream *st = ctx->streams[0];
128 AVIOContext *pb = ctx->pb;
129
130 const AVDictionaryEntry *lang = av_dict_get(st->metadata, "language", NULL,
131 0);
132 const char *printed_lang = (lang && lang->value) ? lang->value : "";
133
134 ttml_ctx->document_written = 0;
135 ttml_ctx->input_type = ff_is_ttml_stream_paragraph_based(st->codecpar) ?
136 PACKET_TYPE_PARAGRAPH :
137 PACKET_TYPE_DOCUMENT;
138
139 avpriv_set_pts_info(st, 64, 1, 1000);
140
141 if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) {
142 struct TTMLHeaderParameters header_params;
143 int ret = ttml_set_header_values_from_extradata(
144 st->codecpar, &header_params);
145 if (ret < 0) {
146 av_log(ctx, AV_LOG_ERROR,
147 "Failed to parse TTML header values from extradata: "
148 "%s!\n", av_err2str(ret));
149 return ret;
150 }
151
152 avio_printf(pb, ttml_header_text,
153 header_params.tt_element_params,
154 printed_lang,
155 header_params.pre_body_elements);
156 }
157
158 return 0;
159}
160
161static int ttml_write_packet(AVFormatContext *ctx, AVPacket *pkt)
162{
163 TTMLMuxContext *ttml_ctx = ctx->priv_data;
164 AVIOContext *pb = ctx->pb;
165
166 switch (ttml_ctx->input_type) {
167 case PACKET_TYPE_PARAGRAPH:
168 // write out a paragraph element with the given contents.
169 avio_printf(pb, " <p\n");
170 ttml_write_time(pb, " begin", pkt->pts);
171 avio_w8(pb, '\n');
172 ttml_write_time(pb, " end", pkt->pts + pkt->duration);
173 avio_printf(pb, ">");
174 avio_write(pb, pkt->data, pkt->size);
175 avio_printf(pb, "</p>\n");
176 break;
177 case PACKET_TYPE_DOCUMENT:
178 // dump the given document out as-is.
179 if (ttml_ctx->document_written) {
180 av_log(ctx, AV_LOG_ERROR,
181 "Attempting to write multiple TTML documents into a "
182 "single document! The XML specification forbids this "
183 "as there has to be a single root tag.\n");
184 return AVERROR(EINVAL);
185 }
186 avio_write(pb, pkt->data, pkt->size);
187 ttml_ctx->document_written = 1;
188 break;
189 default:
190 av_log(ctx, AV_LOG_ERROR,
191 "Internal error: invalid TTML input packet type: %d!\n",
192 ttml_ctx->input_type);
193 return AVERROR_BUG;
194 }
195
196 return 0;
197}
198
199static int ttml_write_trailer(AVFormatContext *ctx)
200{
201 TTMLMuxContext *ttml_ctx = ctx->priv_data;
202 AVIOContext *pb = ctx->pb;
203
204 if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH)
205 avio_printf(pb, ttml_footer_text);
206
207 return 0;
208}
209
210const FFOutputFormat ff_ttml_muxer = {
211 .p.name = "ttml",
212 .p.long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"),
213 .p.extensions = "ttml",
214 .p.mime_type = "text/ttml",
215 .priv_data_size = sizeof(TTMLMuxContext),
216 .p.flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS |
217 AVFMT_TS_NONSTRICT,
218 .p.video_codec = AV_CODEC_ID_NONE,
219 .p.audio_codec = AV_CODEC_ID_NONE,
220 .p.subtitle_codec = AV_CODEC_ID_TTML,
221 .flags_internal = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
222 FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,
223 .write_header = ttml_write_header,
224 .write_packet = ttml_write_packet,
225 .write_trailer = ttml_write_trailer,
226};
ff_ttml_muxer
const FFOutputFormat ff_ttml_muxer
Definition ttmlenc.c:210
ctx
static AVFormatContext * ctx
Definition api-movenc-test.c:49
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:834
avformat.h
Main libavformat public API header.
AVFMT_VARIABLE_FPS
#define AVFMT_VARIABLE_FPS
Format allows variable fps.
Definition avformat.h:501
AVFMT_TS_NONSTRICT
#define AVFMT_TS_NONSTRICT
Format does not require strictly increasing timestamps, but they must still be monotonic.
Definition avformat.h:507
AVFMT_GLOBALHEADER
#define AVFMT_GLOBALHEADER
Format wants global header.
Definition avformat.h:497
avio_w8
void avio_w8(AVIOContext *s, int b)
Definition aviobuf.c:184
avio_printf
int avio_printf(AVIOContext *s, const char *fmt,...) av_printf_format(2
Writes a formatted string to the context.
avio_write
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition aviobuf.c:206
NULL
#define NULL
Definition coverity.c:32
int64_t
long long int64_t
Definition coverity.c:34
min
#define min(a, b)
Definition cuda_runtime.h:34
pkt
static AVPacket * pkt
Definition demux_decode.c:55
value
double value
Definition eval.c:102
AV_CODEC_ID_TTML
@ AV_CODEC_ID_TTML
Definition codec_id.h:590
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition codec_id.h:48
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:60
AVERROR_BUG
#define AVERROR_BUG
Internal bug, also see AVERROR_BUG2.
Definition error.h:52
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition error.h:61
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:122
AVERROR
#define AVERROR(e)
Definition error.h:45
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition log.h:210
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
TTML_DEFAULT_NAMESPACING
#define TTML_DEFAULT_NAMESPACING
Definition ttmlenc.h:28
TTMLENC_EXTRADATA_SIGNATURE_SIZE
#define TTMLENC_EXTRADATA_SIGNATURE_SIZE
Definition ttmlenc.h:26
ttml_write_header
static int ttml_write_header(AVFormatContext *ctx)
Definition ttmlenc.c:124
TTMLPacketType
TTMLPacketType
Definition ttmlenc.c:38
PACKET_TYPE_PARAGRAPH
@ PACKET_TYPE_PARAGRAPH
Definition ttmlenc.c:39
PACKET_TYPE_DOCUMENT
@ PACKET_TYPE_DOCUMENT
Definition ttmlenc.c:40
ttml_write_trailer
static int ttml_write_trailer(AVFormatContext *ctx)
Definition ttmlenc.c:199
ttml_set_header_values_from_extradata
static int ttml_set_header_values_from_extradata(AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
Definition ttmlenc.c:82
ttml_write_packet
static int ttml_write_packet(AVFormatContext *ctx, AVPacket *pkt)
Definition ttmlenc.c:161
ttml_footer_text
static const char ttml_footer_text[]
Definition ttmlenc.c:62
ttml_header_text
static const char ttml_header_text[]
Definition ttmlenc.c:53
ttml_write_time
static void ttml_write_time(AVIOContext *pb, const char tag[], int64_t millisec)
Definition ttmlenc.c:67
ff_is_ttml_stream_paragraph_based
static unsigned int ff_is_ttml_stream_paragraph_based(const AVCodecParameters *codecpar)
Definition ttmlenc.h:28
internal.h
common internal API header
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:88
tag
uint32_t tag
Definition movenc.c:2073
FF_OFMT_FLAG_MAX_ONE_OF_EACH
#define FF_OFMT_FLAG_MAX_ONE_OF_EACH
If this flag is set, it indicates that for each codec type whose corresponding default codec (i....
Definition mux.h:50
FF_OFMT_FLAG_ONLY_DEFAULT_CODECS
#define FF_OFMT_FLAG_ONLY_DEFAULT_CODECS
If this flag is set, then the only permitted audio/video/subtitle codec ids are AVOutputFormat....
Definition mux.h:59
AVCodecParameters
This struct describes the properties of an encoded stream.
Definition codec_par.h:49
AVCodecParameters::extradata_size
int extradata_size
Size of the extradata content in bytes.
Definition codec_par.h:75
AVCodecParameters::extradata
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition codec_par.h:71
AVDictionaryEntry::value
char * value
Definition dict.h:92
AVFormatContext
Format I/O context.
Definition avformat.h:1333
AVIOContext
Bytestream IO Context.
Definition avio.h:160
AVPacket
This structure stores compressed data.
Definition packet.h:580
AVStream
Stream structure.
Definition avformat.h:766
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition avformat.h:789
AVStream::metadata
AVDictionary * metadata
Definition avformat.h:846
TTMLHeaderParameters::pre_body_elements
const char * pre_body_elements
Definition ttmlenc.c:45
TTMLHeaderParameters::tt_element_params
const char * tt_element_params
Definition ttmlenc.c:44
TTMLMuxContext::input_type
enum TTMLPacketType input_type
Definition ttmlenc.c:49
TTMLMuxContext::document_written
unsigned int document_written
Definition ttmlenc.c:50
av_log
#define av_log(a,...)
Definition tableprint_vlc.h:27
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