ffmpeg/libavformat/mccdec.c

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/*
* MCC subtitle demuxer
* Copyright (c) 2020 Paul B Mahol
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "internal.h"
#include "subtitles.h"
#include "libavutil/avstring.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
typedef struct MCCContext {
FFDemuxSubtitlesQueue q;
} MCCContext;
static int mcc_probe(const AVProbeData *p)
{
char buf[28];
FFTextReader tr;
ff_text_init_buf(&tr, p->buf, p->buf_size);
while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')
ff_text_r8(&tr);
ff_text_read(&tr, buf, sizeof(buf));
if (!memcmp(buf, "File Format=MacCaption_MCC V", 28))
return AVPROBE_SCORE_MAX;
return 0;
}
static int convert(uint8_t x)
{
if (x >= 'a')
x -= 87;
else if (x >= 'A')
x -= 55;
else
x -= '0';
return x;
}
typedef struct alias {
uint8_t key;
int len;
const char *value;
} alias;
static const alias aliases[20] = {
{ .key = 16, .len = 3, .value = "\xFA\x0\x0", },
{ .key = 17, .len = 6, .value = "\xFA\x0\x0\xFA\x0\x0", },
{ .key = 18, .len = 9, .value = "\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0", },
{ .key = 19, .len = 12, .value = "\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0", },
{ .key = 20, .len = 15, .value = "\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0", },
{ .key = 21, .len = 18, .value = "\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0", },
{ .key = 22, .len = 21, .value = "\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0", },
{ .key = 23, .len = 24, .value = "\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0", },
{ .key = 24, .len = 27, .value = "\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0\xFA\x0\x0", },
{ .key = 25, .len = 3, .value = "\xFB\x80\x80", },
{ .key = 26, .len = 3, .value = "\xFC\x80\x80", },
{ .key = 27, .len = 3, .value = "\xFD\x80\x80", },
{ .key = 28, .len = 2, .value = "\x96\x69", },
{ .key = 29, .len = 2, .value = "\x61\x01", },
{ .key = 30, .len = 3, .value = "\xFC\x80\x80", },
{ .key = 31, .len = 3, .value = "\xFC\x80\x80", },
{ .key = 32, .len = 4, .value = "\xE1\x00\x00\x00", },
{ .key = 33, .len = 0, .value = NULL, },
{ .key = 34, .len = 0, .value = NULL, },
{ .key = 35, .len = 1, .value = "\x0", },
};
static int mcc_read_header(AVFormatContext *s)
{
MCCContext *mcc = s->priv_data;
AVStream *st = avformat_new_stream(s, NULL);
AVRational rate;
int64_t ts, pos;
uint8_t out[4096];
char line[4096];
FFTextReader tr;
int ret = 0;
ff_text_init_avio(s, &tr, s->pb);
if (!st)
return AVERROR(ENOMEM);
st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
st->codecpar->codec_id = AV_CODEC_ID_EIA_608;
avpriv_set_pts_info(st, 64, 1, 30);
while (!ff_text_eof(&tr)) {
int hh, mm, ss, fs, i = 0, j = 0;
int start = 12, count = 0;
AVPacket *sub;
char *lline;
ff_subtitles_read_line(&tr, line, sizeof(line));
if (!strncmp(line, "File Format=MacCaption_MCC V", 28))
continue;
if (!strncmp(line, "//", 2))
continue;
if (!strncmp(line, "Time Code Rate=", 15)) {
char *rate_str = line + 15;
char *df = NULL;
int num = -1, den = -1;
if (rate_str[0]) {
num = strtol(rate_str, &df, 10);
den = 1;
if (df && !av_strncasecmp(df, "DF", 2)) {
av_reduce(&num, &den, num * 1000LL, 1001, INT_MAX);
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}
}
if (num > 0 && den > 0) {
rate = av_make_q(num, den);
avpriv_set_pts_info(st, 64, rate.den, rate.num);
}
continue;
}
if (av_sscanf(line, "%d:%d:%d:%d", &hh, &mm, &ss, &fs) != 4)
continue;
ts = av_sat_add64(av_rescale(hh * 3600LL + mm * 60LL + ss, rate.num, rate.den), fs);
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lline = (char *)&line;
lline += 12;
pos = ff_text_pos(&tr);
while (lline[i]) {
uint8_t v = convert(lline[i]);
if (v >= 16 && v <= 35) {
int idx = v - 16;
if (aliases[idx].len) {
if (j >= sizeof(out) - 1 - aliases[idx].len) {
j = 0;
break;
}
memcpy(out + j, aliases[idx].value, aliases[idx].len);
j += aliases[idx].len;
}
} else {
uint8_t vv;
if (i + 13 >= sizeof(line) - 1)
break;
vv = convert(lline[i + 1]);
if (j >= sizeof(out) - 1) {
j = 0;
break;
}
out[j++] = vv | (v << 4);
i++;
}
i++;
}
out[j] = 0;
if (out[7] & 0x80)
start += 4;
count = (out[11] & 0x1f) * 3;
if (j < start + count + 1)
continue;
if (!count)
continue;
sub = ff_subtitles_queue_insert(&mcc->q, out + start, count, 0);
if (!sub)
return AVERROR(ENOMEM);
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sub->pos = pos;
sub->pts = ts;
sub->duration = 1;
}
ff_subtitles_queue_finalize(s, &mcc->q);
return ret;
}
const AVInputFormat ff_mcc_demuxer = {
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.name = "mcc",
.long_name = NULL_IF_CONFIG_SMALL("MacCaption"),
.priv_data_size = sizeof(MCCContext),
.flags_internal = FF_FMT_INIT_CLEANUP,
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.read_probe = mcc_probe,
.read_header = mcc_read_header,
.extensions = "mcc",
.read_packet = ff_subtitles_read_packet,
.read_seek2 = ff_subtitles_read_seek,
.read_close = ff_subtitles_read_close,
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};