mpv/demux/demux_libass.c

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/*
* This file is part of mpv.
*
* 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/>.
*/
// Note: just wraps libass, and makes the subtitle track available though
// sh_sub->track. It doesn't produce packets and doesn't support seeking.
#include <ass/ass.h>
#include <ass/ass_types.h>
#include "options/options.h"
#include "common/msg.h"
#include "misc/charset_conv.h"
#include "stream/stream.h"
#include "demux.h"
#define PROBE_SIZE (8 * 1024)
static void message_callback(int level, const char *format, va_list va, void *ctx)
{
// ignore
}
static int d_check_file(struct demuxer *demuxer, enum demux_check check)
{
const char *user_cp = demuxer->opts->sub_cp;
struct stream *s = demuxer->stream;
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struct mp_log *log = demuxer->log;
if (!demuxer->params || !demuxer->params->expect_subtitle)
return -1;
if (check >= DEMUX_CHECK_UNSAFE) {
ASS_Library *lib = ass_library_init();
if (!lib)
return -1;
ass_set_message_cb(lib, message_callback, NULL);
// Probe by loading a part of the beginning of the file with libass.
// Incomplete scripts are usually ok, and we hope libass is not verbose
// when dealing with (from its perspective) completely broken binary
// garbage.
bstr buf = stream_peek(s, PROBE_SIZE);
// Older versions of libass will overwrite the input buffer, and despite
// passing length, expect a 0 termination.
void *tmp = talloc_size(NULL, buf.len + 1);
memcpy(tmp, buf.start, buf.len);
buf.start = tmp;
buf.start[buf.len] = '\0';
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bstr cbuf = mp_charset_guess_and_conv_to_utf8(log, buf, user_cp,
MP_ICONV_ALLOW_CUTOFF);
if (cbuf.start == NULL)
cbuf = buf;
ASS_Track *track = ass_read_memory(lib, cbuf.start, cbuf.len, NULL);
bool ok = !!track;
if (cbuf.start != buf.start)
talloc_free(cbuf.start);
talloc_free(buf.start);
if (track)
ass_free_track(track);
ass_library_done(lib);
if (!ok)
return -1;
}
// Actually load the full thing.
bstr buf = stream_read_complete(s, NULL, 100000000);
if (!buf.start) {
MP_ERR(demuxer, "Refusing to load subtitle file "
"larger than 100 MB: %s\n", demuxer->filename);
return -1;
}
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bstr cbuf = mp_charset_guess_and_conv_to_utf8(log, buf, user_cp,
MP_ICONV_VERBOSE);
if (cbuf.start == NULL)
cbuf = buf;
if (cbuf.start != buf.start)
talloc_free(buf.start);
talloc_steal(demuxer, cbuf.start);
struct sh_stream *sh = new_sh_stream(demuxer, STREAM_SUB);
sh->codec = "ass";
sh->extradata = cbuf.start;
sh->extradata_size = cbuf.len;
demuxer->seekable = true;
demuxer->fully_read = true;
return 0;
}
const struct demuxer_desc demuxer_desc_libass = {
.name = "libass",
.desc = "ASS/SSA subtitles (libass)",
.open = d_check_file,
};