mirror of
https://github.com/mpv-player/mpv
synced 2024-12-27 09:32:40 +00:00
95 lines
2.8 KiB
C
95 lines
2.8 KiB
C
/*
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* This file is part of mpv.
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*
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* SRT timestamp parsing code lifted from FFmpeg srtdec.c (LGPL).
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*
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* mpv is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* mpv 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with mpv. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdlib.h>
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#include <inttypes.h>
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#include <assert.h>
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#include "mpvcore/bstr.h"
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#include "sd.h"
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/*
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* Background:
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*
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* Libav's .srt demuxer outputs packets that contain parts of the subtitle
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* event header. Also, the packet duration is not set (they don't parse it
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* on the demuxer side). As a result, the srt demuxer is useless.
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*
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* However, we can fix it by parsing the header, which spares us from writing
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* a full SRT demuxer.
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*
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* Newer versions of FFmpeg do not have this problem. To avoid compatibility
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* problems, they changed the codec name from "srt" to "subrip".
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*
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* Summary: this is a hack for broken SRT stuff in Libav.
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*
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*/
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static bool supports_format(const char *format)
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{
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return format && strcmp(format, "srt") == 0;
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}
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static int init(struct sd *sd)
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{
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sd->output_codec = "subrip";
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return 0;
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}
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static bool parse_pts(bstr header, double *duration)
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{
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char buf[200];
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snprintf(buf, sizeof(buf), "%.*s", BSTR_P(header));
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int hh1, mm1, ss1, ms1;
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int hh2, mm2, ss2, ms2;
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if (sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d",
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&hh1, &mm1, &ss1, &ms1, &hh2, &mm2, &ss2, &ms2) >= 8)
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{
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int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;
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int64_t end = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;
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*duration = (end - start) / 1000.0;
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return true;
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}
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return false;
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}
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static void decode(struct sd *sd, struct demux_packet *packet)
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{
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bstr data = {packet->buffer, packet->len};
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// Remove the broken header. It's usually on the second or first line.
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bstr left = data;
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while (left.len) {
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bstr line = bstr_getline(left, &left);
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if (parse_pts(line, &packet->duration)) {
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data = left;
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break;
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}
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}
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sd_conv_add_packet(sd, data.start, data.len, packet->pts, packet->duration);
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}
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const struct sd_functions sd_lavf_srt = {
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.name = "lavf_srt",
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.supports_format = supports_format,
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.init = init,
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.decode = decode,
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.get_converted = sd_conv_def_get_converted,
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.reset = sd_conv_def_reset,
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};
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