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/*
* This file is part of mpv.
*
* SRT timestamp parsing code lifted from FFmpeg srtdec.c (LGPL).
*
* mpv is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <inttypes.h>
#include <assert.h>
#include "bstr/bstr.h"
#include "sd.h"
/*
* Background:
*
* Libav's .srt demuxer outputs packets that contain parts of the subtitle
* event header. Also, the packet duration is not set (they don't parse it
* on the demuxer side). As a result, the srt demuxer is useless.
*
* However, we can fix it by parsing the header, which spares us from writing
* a full SRT demuxer.
*
* Newer versions of FFmpeg do not have this problem. To avoid compatibility
* problems, they changed the codec name from "srt" to "subrip".
*
* Summary: this is a hack for broken SRT stuff in Libav.
*
*/
static bool supports_format(const char *format)
{
return format && strcmp(format, "srt") == 0;
}
static int init(struct sd *sd)
{
sd->output_codec = "subrip";
return 0;
}
static bool parse_pts(bstr header, double *duration)
{
char buf[200];
snprintf(buf, sizeof(buf), "%.*s", BSTR_P(header));
int hh1, mm1, ss1, ms1;
int hh2, mm2, ss2, ms2;
if (sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d",
&hh1, &mm1, &ss1, &ms1, &hh2, &mm2, &ss2, &ms2) >= 8)
{
int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;
int64_t end = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;
*duration = (end - start) / 1000.0;
return true;
}
return false;
}
static void decode(struct sd *sd, struct demux_packet *packet)
{
bstr data = {packet->buffer, packet->len};
// Remove the broken header. It's usually on the second or first line.
bstr left = data;
while (left.len) {
bstr line = bstr_getline(left, &left);
if (parse_pts(line, &packet->duration)) {
data = left;
break;
}
}
sd_conv_add_packet(sd, data.start, data.len, packet->pts, packet->duration);
}
const struct sd_functions sd_lavf_srt = {
.name = "lavf_srt",
.supports_format = supports_format,
.init = init,
.decode = decode,
.get_converted = sd_conv_def_get_converted,
.reset = sd_conv_def_reset,
};
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