367 lines
11 KiB
C
367 lines
11 KiB
C
/*
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* TED Talks captions format decoder
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* Copyright (c) 2012 Nicolas George
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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 "libavutil/bprint.h"
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#include "libavutil/log.h"
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#include "libavutil/opt.h"
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#include "avformat.h"
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#include "internal.h"
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#include "subtitles.h"
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typedef struct {
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AVClass *class;
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int64_t start_time;
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FFDemuxSubtitlesQueue subs;
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} TEDCaptionsDemuxer;
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static const AVOption tedcaptions_options[] = {
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{ "start_time", "set the start time (offset) of the subtitles, in ms",
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offsetof(TEDCaptionsDemuxer, start_time), AV_OPT_TYPE_INT64,
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{ .i64 = 15000 }, INT64_MIN, INT64_MAX,
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AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM },
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{ NULL },
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};
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static const AVClass tedcaptions_demuxer_class = {
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.class_name = "tedcaptions_demuxer",
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.item_name = av_default_item_name,
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.option = tedcaptions_options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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#define BETWEEN(a, amin, amax) ((unsigned)((a) - (amin)) <= (amax) - (amin))
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#define HEX_DIGIT_TEST(c) (BETWEEN(c, '0', '9') || BETWEEN((c) | 32, 'a', 'z'))
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#define HEX_DIGIT_VAL(c) ((c) <= '9' ? (c) - '0' : ((c) | 32) - 'a' + 10)
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#define ERR_CODE(c) ((c) < 0 ? (c) : AVERROR_INVALIDDATA)
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static void av_bprint_utf8(AVBPrint *bp, unsigned c)
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{
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int bytes, i;
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if (c <= 0x7F) {
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av_bprint_chars(bp, c, 1);
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return;
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}
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bytes = (av_log2(c) - 2) / 5;
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av_bprint_chars(bp, (c >> (bytes * 6)) | ((0xFF80 >> bytes) & 0xFF), 1);
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for (i = bytes - 1; i >= 0; i--)
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av_bprint_chars(bp, ((c >> (i * 6)) & 0x3F) | 0x80, 1);
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}
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static void next_byte(AVIOContext *pb, int *cur_byte)
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{
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uint8_t b;
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int ret = avio_read(pb, &b, 1);
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*cur_byte = ret > 0 ? b : ret == 0 ? AVERROR_EOF : ret;
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}
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static void skip_spaces(AVIOContext *pb, int *cur_byte)
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{
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while (*cur_byte == ' ' || *cur_byte == '\t' ||
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*cur_byte == '\n' || *cur_byte == '\r')
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next_byte(pb, cur_byte);
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}
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static int expect_byte(AVIOContext *pb, int *cur_byte, uint8_t c)
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{
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skip_spaces(pb, cur_byte);
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if (*cur_byte != c)
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return ERR_CODE(*cur_byte);
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next_byte(pb, cur_byte);
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return 0;
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}
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static int parse_string(AVIOContext *pb, int *cur_byte, AVBPrint *bp, int full)
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{
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int ret;
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av_bprint_init(bp, 0, full ? -1 : 1);
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ret = expect_byte(pb, cur_byte, '"');
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if (ret < 0)
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goto fail;
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while (*cur_byte > 0 && *cur_byte != '"') {
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if (*cur_byte == '\\') {
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next_byte(pb, cur_byte);
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if (*cur_byte < 0) {
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ret = AVERROR_INVALIDDATA;
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goto fail;
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}
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if ((*cur_byte | 32) == 'u') {
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unsigned chr = 0, i;
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for (i = 0; i < 4; i++) {
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next_byte(pb, cur_byte);
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if (!HEX_DIGIT_TEST(*cur_byte)) {
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ret = ERR_CODE(*cur_byte);
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goto fail;
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}
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chr = chr * 16 + HEX_DIGIT_VAL(*cur_byte);
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}
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av_bprint_utf8(bp, chr);
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} else {
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av_bprint_chars(bp, *cur_byte, 1);
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}
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} else {
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av_bprint_chars(bp, *cur_byte, 1);
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}
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next_byte(pb, cur_byte);
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}
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ret = expect_byte(pb, cur_byte, '"');
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if (ret < 0)
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goto fail;
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if (full && !av_bprint_is_complete(bp)) {
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ret = AVERROR(ENOMEM);
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goto fail;
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}
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return 0;
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fail:
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av_bprint_finalize(bp, NULL);
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return ret;
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}
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static int parse_label(AVIOContext *pb, int *cur_byte, AVBPrint *bp)
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{
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int ret;
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ret = parse_string(pb, cur_byte, bp, 0);
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if (ret < 0)
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return ret;
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ret = expect_byte(pb, cur_byte, ':');
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if (ret < 0)
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return ret;
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return 0;
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}
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static int parse_boolean(AVIOContext *pb, int *cur_byte, int *result)
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{
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static const char * const text[] = { "false", "true" };
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const char *p;
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int i;
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skip_spaces(pb, cur_byte);
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for (i = 0; i < 2; i++) {
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p = text[i];
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if (*cur_byte != *p)
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continue;
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for (; *p; p++, next_byte(pb, cur_byte))
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if (*cur_byte != *p)
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return AVERROR_INVALIDDATA;
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if (BETWEEN(*cur_byte | 32, 'a', 'z'))
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return AVERROR_INVALIDDATA;
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*result = i;
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return 0;
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}
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return AVERROR_INVALIDDATA;
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}
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static int parse_int(AVIOContext *pb, int *cur_byte, int64_t *result)
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{
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int64_t val = 0;
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skip_spaces(pb, cur_byte);
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if ((unsigned)*cur_byte - '0' > 9)
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return AVERROR_INVALIDDATA;
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while (BETWEEN(*cur_byte, '0', '9')) {
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val = val * 10 + (*cur_byte - '0');
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next_byte(pb, cur_byte);
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}
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*result = val;
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return 0;
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}
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static int parse_file(AVIOContext *pb, FFDemuxSubtitlesQueue *subs)
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{
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int ret, cur_byte, start_of_par;
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AVBPrint label, content;
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int64_t pos, start, duration;
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AVPacket *pkt;
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next_byte(pb, &cur_byte);
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ret = expect_byte(pb, &cur_byte, '{');
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if (ret < 0)
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return AVERROR_INVALIDDATA;
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ret = parse_label(pb, &cur_byte, &label);
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if (ret < 0 || strcmp(label.str, "captions"))
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return AVERROR_INVALIDDATA;
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ret = expect_byte(pb, &cur_byte, '[');
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if (ret < 0)
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return AVERROR_INVALIDDATA;
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while (1) {
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content.size = 0;
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start = duration = AV_NOPTS_VALUE;
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ret = expect_byte(pb, &cur_byte, '{');
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if (ret < 0)
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return ret;
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pos = avio_tell(pb) - 1;
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while (1) {
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ret = parse_label(pb, &cur_byte, &label);
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if (ret < 0)
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return ret;
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if (!strcmp(label.str, "startOfParagraph")) {
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ret = parse_boolean(pb, &cur_byte, &start_of_par);
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if (ret < 0)
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return ret;
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} else if (!strcmp(label.str, "content")) {
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ret = parse_string(pb, &cur_byte, &content, 1);
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if (ret < 0)
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return ret;
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} else if (!strcmp(label.str, "startTime")) {
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ret = parse_int(pb, &cur_byte, &start);
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if (ret < 0)
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return ret;
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} else if (!strcmp(label.str, "duration")) {
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ret = parse_int(pb, &cur_byte, &duration);
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if (ret < 0)
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return ret;
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} else {
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return AVERROR_INVALIDDATA;
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}
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skip_spaces(pb, &cur_byte);
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if (cur_byte != ',')
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break;
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next_byte(pb, &cur_byte);
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}
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ret = expect_byte(pb, &cur_byte, '}');
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if (ret < 0)
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return ret;
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if (!content.size || start == AV_NOPTS_VALUE ||
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duration == AV_NOPTS_VALUE)
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return AVERROR_INVALIDDATA;
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pkt = ff_subtitles_queue_insert(subs, content.str, content.len, 0);
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if (!pkt)
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return AVERROR(ENOMEM);
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pkt->pos = pos;
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pkt->pts = start;
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pkt->duration = duration;
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av_bprint_finalize(&content, NULL);
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skip_spaces(pb, &cur_byte);
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if (cur_byte != ',')
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break;
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next_byte(pb, &cur_byte);
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}
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ret = expect_byte(pb, &cur_byte, ']');
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if (ret < 0)
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return ret;
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ret = expect_byte(pb, &cur_byte, '}');
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if (ret < 0)
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return ret;
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skip_spaces(pb, &cur_byte);
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if (cur_byte != AVERROR_EOF)
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return ERR_CODE(cur_byte);
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return 0;
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}
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static av_cold int tedcaptions_read_header(AVFormatContext *avf)
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{
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TEDCaptionsDemuxer *tc = avf->priv_data;
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AVStream *st;
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int ret, i;
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AVPacket *last;
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ret = parse_file(avf->pb, &tc->subs);
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if (ret < 0) {
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if (ret == AVERROR_INVALIDDATA)
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av_log(avf, AV_LOG_ERROR, "Syntax error near offset %"PRId64".\n",
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avio_tell(avf->pb));
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ff_subtitles_queue_clean(&tc->subs);
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return ret;
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}
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ff_subtitles_queue_finalize(avf, &tc->subs);
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for (i = 0; i < tc->subs.nb_subs; i++)
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tc->subs.subs[i].pts += tc->start_time;
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last = &tc->subs.subs[tc->subs.nb_subs - 1];
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st = avformat_new_stream(avf, NULL);
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if (!st)
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return AVERROR(ENOMEM);
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st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
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st->codec->codec_id = AV_CODEC_ID_TEXT;
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avpriv_set_pts_info(st, 64, 1, 1000);
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st->probe_packets = 0;
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st->start_time = 0;
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st->duration = last->pts + last->duration;
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st->cur_dts = 0;
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return 0;
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}
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static int tedcaptions_read_packet(AVFormatContext *avf, AVPacket *packet)
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{
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TEDCaptionsDemuxer *tc = avf->priv_data;
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return ff_subtitles_queue_read_packet(&tc->subs, packet);
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}
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static int tedcaptions_read_close(AVFormatContext *avf)
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{
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TEDCaptionsDemuxer *tc = avf->priv_data;
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ff_subtitles_queue_clean(&tc->subs);
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return 0;
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}
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static av_cold int tedcaptions_read_probe(AVProbeData *p)
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{
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static const char *const tags[] = {
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"\"captions\"", "\"duration\"", "\"content\"",
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"\"startOfParagraph\"", "\"startTime\"",
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};
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unsigned i, count = 0;
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const char *t;
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if (p->buf[strspn(p->buf, " \t\r\n")] != '{')
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return 0;
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for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) {
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if (!(t = strstr(p->buf, tags[i])))
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continue;
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t += strlen(tags[i]);
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t += strspn(t, " \t\r\n");
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if (*t == ':')
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count++;
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}
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return count == FF_ARRAY_ELEMS(tags) ? AVPROBE_SCORE_MAX :
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count ? AVPROBE_SCORE_EXTENSION : 0;
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}
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static int tedcaptions_read_seek(AVFormatContext *avf, int stream_index,
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int64_t min_ts, int64_t ts, int64_t max_ts,
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int flags)
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{
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TEDCaptionsDemuxer *tc = avf->priv_data;
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return ff_subtitles_queue_seek(&tc->subs, avf, stream_index,
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min_ts, ts, max_ts, flags);
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}
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AVInputFormat ff_tedcaptions_demuxer = {
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.name = "tedcaptions",
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.long_name = NULL_IF_CONFIG_SMALL("TED Talks captions"),
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.priv_data_size = sizeof(TEDCaptionsDemuxer),
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.priv_class = &tedcaptions_demuxer_class,
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.read_header = tedcaptions_read_header,
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.read_packet = tedcaptions_read_packet,
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.read_close = tedcaptions_read_close,
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.read_probe = tedcaptions_read_probe,
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.read_seek2 = tedcaptions_read_seek,
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};
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