mirror of https://github.com/FFmpeg/FFmpeg.git
Based off the srt encoder. The following features are unimplemented: - fonts, colors, sizes - alignment and positioning The rest works well. For example, use ffmpeg to convert subtitles into the .vtt format: ffmpeg -i input.srt output.vtt Signed-off-by: Aman Gupta <ffmpeg@tmm1.net> Signed-off-by: Clément Bœsch <u@pkh.me>pull/72/head
Aman Gupta
11 years ago
committed by
Clément Bœsch
parent
d94e255dd1
commit
4372fb7a57
9 changed files with 229 additions and 3 deletions
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/*
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* WebVTT subtitle encoder |
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* Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org> |
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* Copyright (c) 2014 Aman Gupta <ffmpeg@tmm1.net> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include <stdarg.h> |
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#include "avcodec.h" |
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#include "libavutil/avstring.h" |
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#include "libavutil/bprint.h" |
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#include "ass_split.h" |
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#include "ass.h" |
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#define WEBVTT_STACK_SIZE 64 |
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typedef struct { |
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AVCodecContext *avctx; |
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ASSSplitContext *ass_ctx; |
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AVBPrint buffer; |
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unsigned timestamp_end; |
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int count; |
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char stack[WEBVTT_STACK_SIZE]; |
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int stack_ptr; |
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} WebVTTContext; |
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#ifdef __GNUC__ |
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__attribute__ ((__format__ (__printf__, 2, 3))) |
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#endif |
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static void webvtt_print(WebVTTContext *s, const char *str, ...) |
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{ |
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va_list vargs; |
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va_start(vargs, str); |
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av_vbprintf(&s->buffer, str, vargs); |
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va_end(vargs); |
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} |
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static int webvtt_stack_push(WebVTTContext *s, const char c) |
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{ |
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if (s->stack_ptr >= WEBVTT_STACK_SIZE) |
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return AVERROR(EOVERFLOW); |
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s->stack[s->stack_ptr++] = c; |
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return 0; |
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} |
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static char webvtt_stack_pop(WebVTTContext *s) |
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{ |
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if (s->stack_ptr <= 0) |
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return 0; |
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return s->stack[--s->stack_ptr]; |
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} |
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static int webvtt_stack_find(WebVTTContext *s, const char c) |
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{ |
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int i; |
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for (i = s->stack_ptr-1; i >= 0; i--) |
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if (s->stack[i] == c) |
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break; |
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return i; |
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} |
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static void webvtt_close_tag(WebVTTContext *s, char tag) |
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{ |
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webvtt_print(s, "</%c>", tag); |
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} |
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static void webvtt_stack_push_pop(WebVTTContext *s, const char c, int close) |
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{ |
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if (close) { |
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int i = c ? webvtt_stack_find(s, c) : 0; |
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if (i < 0) |
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return; |
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while (s->stack_ptr != i) |
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webvtt_close_tag(s, webvtt_stack_pop(s)); |
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} else if (webvtt_stack_push(s, c) < 0) |
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av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n"); |
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} |
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static void webvtt_style_apply(WebVTTContext *s, const char *style) |
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{ |
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ASSStyle *st = ff_ass_style_get(s->ass_ctx, style); |
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if (st) { |
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if (st->bold != ASS_DEFAULT_BOLD) { |
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webvtt_print(s, "<b>"); |
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webvtt_stack_push(s, 'b'); |
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} |
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if (st->italic != ASS_DEFAULT_ITALIC) { |
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webvtt_print(s, "<i>"); |
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webvtt_stack_push(s, 'i'); |
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} |
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if (st->underline != ASS_DEFAULT_UNDERLINE) { |
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webvtt_print(s, "<u>"); |
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webvtt_stack_push(s, 'u'); |
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} |
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} |
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} |
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static void webvtt_text_cb(void *priv, const char *text, int len) |
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{ |
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WebVTTContext *s = priv; |
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av_bprint_append_data(&s->buffer, text, len); |
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} |
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static void webvtt_new_line_cb(void *priv, int forced) |
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{ |
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webvtt_print(priv, "\n"); |
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} |
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static void webvtt_style_cb(void *priv, char style, int close) |
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{ |
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if (style == 's') // strikethrough unsupported
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return; |
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webvtt_stack_push_pop(priv, style, close); |
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if (!close) |
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webvtt_print(priv, "<%c>", style); |
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} |
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static void webvtt_cancel_overrides_cb(void *priv, const char *style) |
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{ |
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webvtt_stack_push_pop(priv, 0, 1); |
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webvtt_style_apply(priv, style); |
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} |
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static void webvtt_end_cb(void *priv) |
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{ |
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webvtt_stack_push_pop(priv, 0, 1); |
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} |
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static const ASSCodesCallbacks webvtt_callbacks = { |
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.text = webvtt_text_cb, |
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.new_line = webvtt_new_line_cb, |
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.style = webvtt_style_cb, |
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.color = NULL, |
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.font_name = NULL, |
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.font_size = NULL, |
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.alignment = NULL, |
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.cancel_overrides = webvtt_cancel_overrides_cb, |
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.move = NULL, |
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.end = webvtt_end_cb, |
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}; |
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static int webvtt_encode_frame(AVCodecContext *avctx, |
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unsigned char *buf, int bufsize, const AVSubtitle *sub) |
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{ |
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WebVTTContext *s = avctx->priv_data; |
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ASSDialog *dialog; |
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int i, num; |
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av_bprint_clear(&s->buffer); |
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for (i=0; i<sub->num_rects; i++) { |
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if (sub->rects[i]->type != SUBTITLE_ASS) { |
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av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n"); |
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return AVERROR(ENOSYS); |
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} |
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dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num); |
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for (; dialog && num--; dialog++) { |
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webvtt_style_apply(s, dialog->style); |
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ff_ass_split_override_codes(&webvtt_callbacks, s, dialog->text); |
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} |
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} |
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if (!av_bprint_is_complete(&s->buffer)) |
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return AVERROR(ENOMEM); |
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if (!s->buffer.len) |
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return 0; |
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if (s->buffer.len > bufsize) { |
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av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n"); |
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return -1; |
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} |
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memcpy(buf, s->buffer.str, s->buffer.len); |
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return s->buffer.len; |
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} |
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static int webvtt_encode_close(AVCodecContext *avctx) |
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{ |
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WebVTTContext *s = avctx->priv_data; |
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ff_ass_split_free(s->ass_ctx); |
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av_bprint_finalize(&s->buffer, NULL); |
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return 0; |
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} |
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static av_cold int webvtt_encode_init(AVCodecContext *avctx) |
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{ |
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WebVTTContext *s = avctx->priv_data; |
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s->avctx = avctx; |
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s->ass_ctx = ff_ass_split(avctx->subtitle_header); |
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av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED); |
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return s->ass_ctx ? 0 : AVERROR_INVALIDDATA; |
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} |
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AVCodec ff_webvtt_encoder = { |
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.name = "webvtt", |
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.long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"), |
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.type = AVMEDIA_TYPE_SUBTITLE, |
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.id = AV_CODEC_ID_WEBVTT, |
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.priv_data_size = sizeof(WebVTTContext), |
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.init = webvtt_encode_init, |
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.encode_sub = webvtt_encode_frame, |
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.close = webvtt_encode_close, |
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}; |
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@ -0,0 +1 @@ |
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8683216a86e147a98f29dafee33a0987 |
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