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/*
* 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/avstring.h"
#include "libavutil/bprint.h"
#include "ass_split.h"
#include "ass.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;
#ifdef __GNUC__
__attribute__ ((__format__ (__printf__, 2, 3)))
#endif
static 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, num;
av_bprint_clear(&s->buffer);
for (i=0; i<sub->num_rects; i++) {
if (sub->rects[i]->type != SUBTITLE_ASS) {
av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
return AVERROR(ENOSYS);
}
dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num);
for (; dialog && num--; dialog++) {
webvtt_style_apply(s, dialog->style);
ff_ass_split_override_codes(&webvtt_callbacks, s, dialog->text);
}
}
if (!av_bprint_is_complete(&s->buffer))
return AVERROR(ENOMEM);
if (!s->buffer.len)
return 0;
if (s->buffer.len > bufsize) {
av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
return -1;
}
memcpy(buf, s->buffer.str, s->buffer.len);
return s->buffer.len;
}
static int webvtt_encode_close(AVCodecContext *avctx)
{
WebVTTContext *s = avctx->priv_data;
ff_ass_split_free(s->ass_ctx);
av_bprint_finalize(&s->buffer, NULL);
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);
av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
}
AVCodec ff_webvtt_encoder = {
.name = "webvtt",
.long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_WEBVTT,
.priv_data_size = sizeof(WebVTTContext),
.init = webvtt_encode_init,
.encode_sub = webvtt_encode_frame,
.close = webvtt_encode_close,
};
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