1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
|
/*
* TTML subtitle muxer
* Copyright (c) 2020 24i
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* TTML subtitle muxer
* @see https://www.w3.org/TR/ttml1/
* @see https://www.w3.org/TR/ttml2/
* @see https://www.w3.org/TR/ttml-imsc/rec
*/
#include "libavutil/avstring.h"
#include "avformat.h"
#include "internal.h"
#include "libavcodec/ttmlenc.h"
#include "libavutil/internal.h"
enum TTMLPacketType {
PACKET_TYPE_PARAGRAPH,
PACKET_TYPE_DOCUMENT,
};
struct TTMLHeaderParameters {
const char *tt_element_params;
const char *pre_body_elements;
};
typedef struct TTMLMuxContext {
enum TTMLPacketType input_type;
unsigned int document_written;
} TTMLMuxContext;
static const char ttml_header_text[] =
"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
"<tt\n"
"%s"
" xml:lang=\"%s\">\n"
"%s"
" <body>\n"
" <div>\n";
static const char ttml_footer_text[] =
" </div>\n"
" </body>\n"
"</tt>\n";
static void ttml_write_time(AVIOContext *pb, const char tag[],
int64_t millisec)
{
int64_t sec, min, hour;
sec = millisec / 1000;
millisec -= 1000 * sec;
min = sec / 60;
sec -= 60 * min;
hour = min / 60;
min -= 60 * hour;
avio_printf(pb, "%s=\"%02"PRId64":%02"PRId64":%02"PRId64".%03"PRId64"\"",
tag, hour, min, sec, millisec);
}
static int ttml_set_header_values_from_extradata(
AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
{
size_t additional_data_size =
par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE;
char *value =
(char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE;
size_t value_size = av_strnlen(value, additional_data_size);
struct TTMLHeaderParameters local_params = { 0 };
if (!additional_data_size) {
// simple case, we don't have to go through local_params and just
// set default fall-back values (for old extradata format).
header_params->tt_element_params = ttml_default_namespacing;
header_params->pre_body_elements = "";
return 0;
}
if (value_size == additional_data_size ||
value[value_size] != '\0')
return AVERROR_INVALIDDATA;
local_params.tt_element_params = value;
additional_data_size -= value_size + 1;
value += value_size + 1;
if (!additional_data_size)
return AVERROR_INVALIDDATA;
value_size = av_strnlen(value, additional_data_size);
if (value_size == additional_data_size ||
value[value_size] != '\0')
return AVERROR_INVALIDDATA;
local_params.pre_body_elements = value;
*header_params = local_params;
return 0;
}
static int ttml_write_header(AVFormatContext *ctx)
{
TTMLMuxContext *ttml_ctx = ctx->priv_data;
ttml_ctx->document_written = 0;
if (ctx->nb_streams != 1 ||
ctx->streams[0]->codecpar->codec_id != AV_CODEC_ID_TTML) {
av_log(ctx, AV_LOG_ERROR, "Exactly one TTML stream is required!\n");
return AVERROR(EINVAL);
}
{
AVStream *st = ctx->streams[0];
AVIOContext *pb = ctx->pb;
AVDictionaryEntry *lang = av_dict_get(st->metadata, "language", NULL,
0);
const char *printed_lang = (lang && lang->value) ? lang->value : "";
// Not perfect, but decide whether the packet is a document or not
// by the existence of the lavc ttmlenc extradata.
ttml_ctx->input_type = (st->codecpar->extradata &&
st->codecpar->extradata_size >= TTMLENC_EXTRADATA_SIGNATURE_SIZE &&
!memcmp(st->codecpar->extradata,
TTMLENC_EXTRADATA_SIGNATURE,
TTMLENC_EXTRADATA_SIGNATURE_SIZE)) ?
PACKET_TYPE_PARAGRAPH :
PACKET_TYPE_DOCUMENT;
avpriv_set_pts_info(st, 64, 1, 1000);
if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) {
struct TTMLHeaderParameters header_params;
int ret = ttml_set_header_values_from_extradata(
st->codecpar, &header_params);
if (ret < 0) {
av_log(ctx, AV_LOG_ERROR,
"Failed to parse TTML header values from extradata: "
"%s!\n", av_err2str(ret));
return ret;
}
avio_printf(pb, ttml_header_text,
header_params.tt_element_params,
printed_lang,
header_params.pre_body_elements);
}
}
return 0;
}
static int ttml_write_packet(AVFormatContext *ctx, AVPacket *pkt)
{
TTMLMuxContext *ttml_ctx = ctx->priv_data;
AVIOContext *pb = ctx->pb;
switch (ttml_ctx->input_type) {
case PACKET_TYPE_PARAGRAPH:
// write out a paragraph element with the given contents.
avio_printf(pb, " <p\n");
ttml_write_time(pb, " begin", pkt->pts);
avio_w8(pb, '\n');
ttml_write_time(pb, " end", pkt->pts + pkt->duration);
avio_printf(pb, ">");
avio_write(pb, pkt->data, pkt->size);
avio_printf(pb, "</p>\n");
break;
case PACKET_TYPE_DOCUMENT:
// dump the given document out as-is.
if (ttml_ctx->document_written) {
av_log(ctx, AV_LOG_ERROR,
"Attempting to write multiple TTML documents into a "
"single document! The XML specification forbids this "
"as there has to be a single root tag.\n");
return AVERROR(EINVAL);
}
avio_write(pb, pkt->data, pkt->size);
ttml_ctx->document_written = 1;
break;
default:
av_log(ctx, AV_LOG_ERROR,
"Internal error: invalid TTML input packet type: %d!\n",
ttml_ctx->input_type);
return AVERROR_BUG;
}
return 0;
}
static int ttml_write_trailer(AVFormatContext *ctx)
{
TTMLMuxContext *ttml_ctx = ctx->priv_data;
AVIOContext *pb = ctx->pb;
if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH)
avio_printf(pb, ttml_footer_text);
return 0;
}
const AVOutputFormat ff_ttml_muxer = {
.name = "ttml",
.long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"),
.extensions = "ttml",
.mime_type = "text/ttml",
.priv_data_size = sizeof(TTMLMuxContext),
.flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS |
AVFMT_TS_NONSTRICT,
.subtitle_codec = AV_CODEC_ID_TTML,
.write_header = ttml_write_header,
.write_packet = ttml_write_packet,
.write_trailer = ttml_write_trailer,
};
|
