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
|
/*
* WebVTT subtitle encoder
* Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org>
* Copyright (c) 2014 Aman Gupta <ffmpeg@tmm1.net>
*
* 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
*/
#include <stdarg.h>
#include "avcodec.h"
#include "libavutil/bprint.h"
#include "ass_split.h"
#include "ass.h"
#include "codec_internal.h"
#define WEBVTT_STACK_SIZE 64
typedef struct {
AVCodecContext *avctx;
ASSSplitContext *ass_ctx;
AVBPrint buffer;
unsigned timestamp_end;
int count;
char stack[WEBVTT_STACK_SIZE];
int stack_ptr;
} WebVTTContext;
static av_printf_format(2, 3) void webvtt_print(WebVTTContext *s, const char *str, ...)
{
va_list vargs;
va_start(vargs, str);
av_vbprintf(&s->buffer, str, vargs);
va_end(vargs);
}
static int webvtt_stack_push(WebVTTContext *s, const char c)
{
if (s->stack_ptr >= WEBVTT_STACK_SIZE)
return -1;
s->stack[s->stack_ptr++] = c;
return 0;
}
static char webvtt_stack_pop(WebVTTContext *s)
{
if (s->stack_ptr <= 0)
return 0;
return s->stack[--s->stack_ptr];
}
static int webvtt_stack_find(WebVTTContext *s, const char c)
{
int i;
for (i = s->stack_ptr-1; i >= 0; i--)
if (s->stack[i] == c)
break;
return i;
}
static void webvtt_close_tag(WebVTTContext *s, char tag)
{
webvtt_print(s, "</%c>", tag);
}
static void webvtt_stack_push_pop(WebVTTContext *s, const char c, int close)
{
if (close) {
int i = c ? webvtt_stack_find(s, c) : 0;
if (i < 0)
return;
while (s->stack_ptr != i)
webvtt_close_tag(s, webvtt_stack_pop(s));
} else if (webvtt_stack_push(s, c) < 0)
av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n");
}
static void webvtt_style_apply(WebVTTContext *s, const char *style)
{
ASSStyle *st = ff_ass_style_get(s->ass_ctx, style);
if (st) {
if (st->bold != ASS_DEFAULT_BOLD) {
webvtt_print(s, "<b>");
webvtt_stack_push(s, 'b');
}
if (st->italic != ASS_DEFAULT_ITALIC) {
webvtt_print(s, "<i>");
webvtt_stack_push(s, 'i');
}
if (st->underline != ASS_DEFAULT_UNDERLINE) {
webvtt_print(s, "<u>");
webvtt_stack_push(s, 'u');
}
}
}
static void webvtt_text_cb(void *priv, const char *text, int len)
{
WebVTTContext *s = priv;
av_bprint_append_data(&s->buffer, text, len);
}
static void webvtt_new_line_cb(void *priv, int forced)
{
webvtt_print(priv, "\n");
}
static void webvtt_style_cb(void *priv, char style, int close)
{
if (style == 's') // strikethrough unsupported
return;
webvtt_stack_push_pop(priv, style, close);
if (!close)
webvtt_print(priv, "<%c>", style);
}
static void webvtt_cancel_overrides_cb(void *priv, const char *style)
{
webvtt_stack_push_pop(priv, 0, 1);
webvtt_style_apply(priv, style);
}
static void webvtt_end_cb(void *priv)
{
webvtt_stack_push_pop(priv, 0, 1);
}
static const ASSCodesCallbacks webvtt_callbacks = {
.text = webvtt_text_cb,
.new_line = webvtt_new_line_cb,
.style = webvtt_style_cb,
.color = NULL,
.font_name = NULL,
.font_size = NULL,
.alignment = NULL,
.cancel_overrides = webvtt_cancel_overrides_cb,
.move = NULL,
.end = webvtt_end_cb,
};
static int webvtt_encode_frame(AVCodecContext *avctx,
unsigned char *buf, int bufsize, const AVSubtitle *sub)
{
WebVTTContext *s = avctx->priv_data;
ASSDialog *dialog;
int i;
av_bprint_init_for_buffer(&s->buffer, buf, bufsize);
for (i=0; i<sub->num_rects; i++) {
const char *ass = sub->rects[i]->ass;
if (sub->rects[i]->type != SUBTITLE_ASS) {
av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
return AVERROR(EINVAL);
}
dialog = ff_ass_split_dialog(s->ass_ctx, ass);
if (!dialog)
return AVERROR(ENOMEM);
webvtt_style_apply(s, dialog->style);
ff_ass_split_override_codes(&webvtt_callbacks, s, dialog->text);
ff_ass_free_dialog(&dialog);
}
if (!s->buffer.len)
return 0;
if (!av_bprint_is_complete(&s->buffer)) {
av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
return AVERROR_BUFFER_TOO_SMALL;
}
return s->buffer.len;
}
static int webvtt_encode_close(AVCodecContext *avctx)
{
WebVTTContext *s = avctx->priv_data;
ff_ass_split_free(s->ass_ctx);
return 0;
}
static av_cold int webvtt_encode_init(AVCodecContext *avctx)
{
WebVTTContext *s = avctx->priv_data;
s->avctx = avctx;
s->ass_ctx = ff_ass_split(avctx->subtitle_header);
return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
}
const FFCodec ff_webvtt_encoder = {
.p.name = "webvtt",
CODEC_LONG_NAME("WebVTT subtitle"),
.p.type = AVMEDIA_TYPE_SUBTITLE,
.p.id = AV_CODEC_ID_WEBVTT,
.priv_data_size = sizeof(WebVTTContext),
.init = webvtt_encode_init,
FF_CODEC_ENCODE_SUB_CB(webvtt_encode_frame),
.close = webvtt_encode_close,
};
|
