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0fc975c0d3
Unlike what the old comment suggested, standard ASS has no character escape mechanism, but a closing curly bracket doesn't even need one. For manual authored sub files using a full-width variant of an appropriate font and with scaling and spacing modifiers is a common workaround. This is not an option here, but we can still make things much less bad. Now the desired opening bracket still shows up in libass, and standard renders will merely display a backslash in its place instead of stripping the following text like before.
111 lines
3.3 KiB
C
111 lines
3.3 KiB
C
/*
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* Copyright (c) 2012 Clément Bœsch
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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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/**
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* @file
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* WebVTT subtitle decoder
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* @see http://dev.w3.org/html5/webvtt/
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* @todo need to support extended markups and cue settings
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*/
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#include "avcodec.h"
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#include "ass.h"
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#include "codec_internal.h"
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#include "libavutil/bprint.h"
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static const struct {
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const char *from;
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const char *to;
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} webvtt_tag_replace[] = {
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{"<i>", "{\\i1}"}, {"</i>", "{\\i0}"},
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{"<b>", "{\\b1}"}, {"</b>", "{\\b0}"},
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{"<u>", "{\\u1}"}, {"</u>", "{\\u0}"},
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{"{", "\\{{}"}, {"\\", "\\\xe2\x81\xa0"}, // escape to avoid ASS markup conflicts
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{">", ">"}, {"<", "<"},
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{"‎", "\xe2\x80\x8e"}, {"‏", "\xe2\x80\x8f"},
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{"&", "&"}, {" ", "\\h"},
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};
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static int webvtt_event_to_ass(AVBPrint *buf, const char *p)
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{
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int i, again = 0, skip = 0;
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while (*p) {
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for (i = 0; i < FF_ARRAY_ELEMS(webvtt_tag_replace); i++) {
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const char *from = webvtt_tag_replace[i].from;
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const size_t len = strlen(from);
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if (!strncmp(p, from, len)) {
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av_bprintf(buf, "%s", webvtt_tag_replace[i].to);
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p += len;
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again = 1;
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break;
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}
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}
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if (!*p)
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break;
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if (again) {
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again = 0;
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skip = 0;
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continue;
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}
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if (*p == '<')
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skip = 1;
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else if (*p == '>')
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skip = 0;
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else if (p[0] == '\n' && p[1])
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av_bprintf(buf, "\\N");
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else if (!skip && *p != '\r')
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av_bprint_chars(buf, *p, 1);
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p++;
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}
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return 0;
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}
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static int webvtt_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
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int *got_sub_ptr, const AVPacket *avpkt)
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{
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int ret = 0;
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const char *ptr = avpkt->data;
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FFASSDecoderContext *s = avctx->priv_data;
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AVBPrint buf;
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av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
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if (ptr && avpkt->size > 0 && !webvtt_event_to_ass(&buf, ptr))
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ret = ff_ass_add_rect(sub, buf.str, s->readorder++, 0, NULL, NULL);
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av_bprint_finalize(&buf, NULL);
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if (ret < 0)
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return ret;
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*got_sub_ptr = sub->num_rects > 0;
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return avpkt->size;
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}
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const FFCodec ff_webvtt_decoder = {
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.p.name = "webvtt",
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CODEC_LONG_NAME("WebVTT subtitle"),
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.p.type = AVMEDIA_TYPE_SUBTITLE,
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.p.id = AV_CODEC_ID_WEBVTT,
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FF_CODEC_DECODE_SUB_CB(webvtt_decode_frame),
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.init = ff_ass_subtitle_header_default,
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.flush = ff_ass_decoder_flush,
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.priv_data_size = sizeof(FFASSDecoderContext),
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};
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