103 lines
3.1 KiB
C
103 lines
3.1 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 "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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{"{", "\\{"}, {"}", "\\}"}, // escape to avoid ASS markup conflicts
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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, 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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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 (*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,
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void *data, int *got_sub_ptr, AVPacket *avpkt)
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{
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int ret = 0;
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AVSubtitle *sub = data;
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const char *ptr = avpkt->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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int ts_start = av_rescale_q(avpkt->pts, avctx->time_base, (AVRational){1,100});
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int ts_duration = avpkt->duration != -1 ?
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av_rescale_q(avpkt->duration, avctx->time_base, (AVRational){1,100}) : -1;
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ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_duration);
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}
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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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AVCodec ff_webvtt_decoder = {
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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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.decode = webvtt_decode_frame,
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.init = ff_ass_subtitle_header_default,
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};
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