FFmpeg/libavformat/srtdec.c
Clément Bœsch cc88734c3c lavf/srtdec: trim line break event separators from packet.
The muxer add them automatically, so this avoid having a bunch of line
breaks all over the output files. One '\n' is still kept/added because
the lavc subrip decoder seems to have trouble with line ending abruptly
(it doesn't flush correctly the tags). This bug is harmless but should
be fixed; though, this doesn't look like a trivial change. When this bug
gets fixed, we can consider removing the '\n' at the end of the packet.

The 2048B buffer limit was also removed while moving to AVBPrint API.
Note that this doesn't really matter since the decoder is limited as
well.
2012-11-20 22:38:39 +01:00

176 lines
5.1 KiB
C

/*
* SubRip subtitle demuxer
* Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org>
*
* 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 "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
static int srt_probe(AVProbeData *p)
{
unsigned char *ptr = p->buf;
int i, v, num = 0;
if (AV_RB24(ptr) == 0xEFBBBF)
ptr += 3; /* skip UTF-8 BOM */
for (i=0; i<2; i++) {
if ((num == i || num + 1 == i)
&& sscanf(ptr, "%*d:%*2d:%*2d%*1[,.]%*3d --> %*d:%*2d:%*2d%*1[,.]%3d", &v) == 1)
return AVPROBE_SCORE_MAX;
num = atoi(ptr);
ptr += strcspn(ptr, "\n") + 1;
}
return 0;
}
static int srt_read_header(AVFormatContext *s)
{
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
return AVERROR(ENOMEM);
avpriv_set_pts_info(st, 64, 1, 1000);
st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
st->codec->codec_id = AV_CODEC_ID_SUBRIP;
return 0;
}
static int64_t get_pts(const char **buf, int *duration,
int32_t *x1, int32_t *y1, int32_t *x2, int32_t *y2)
{
int i;
for (i=0; i<2; i++) {
int hh1, mm1, ss1, ms1;
int hh2, mm2, ss2, ms2;
if (sscanf(*buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
"%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
&hh1, &mm1, &ss1, &ms1,
&hh2, &mm2, &ss2, &ms2,
x1, x2, y1, y2) >= 8) {
int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;
int64_t end = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;
*duration = end - start;
*buf += strcspn(*buf, "\n") + 1;
return start;
}
*buf += strcspn(*buf, "\n") + 1;
}
return AV_NOPTS_VALUE;
}
static inline int is_eol(char c)
{
return c == '\r' || c == '\n';
}
static void read_chunk(AVIOContext *pb, AVBPrint *buf)
{
char eol_buf[5];
int n = 0, i = 0, nb_eol = 0;
for (;;) {
char c = avio_r8(pb);
if (!c)
break;
/* ignore all initial line breaks */
if (n == 0 && is_eol(c))
continue;
/* line break buffering: we don't want to add the trailing \r\n */
if (is_eol(c)) {
nb_eol += c == '\n';
if (nb_eol == 2)
break;
eol_buf[i++] = c;
if (i == sizeof(eol_buf) - 1)
break;
continue;
}
/* only one line break followed by data: we flush the line breaks
* buffer */
if (i) {
eol_buf[i] = 0;
av_bprintf(buf, "%s", eol_buf);
i = nb_eol = 0;
}
av_bprint_chars(buf, c, 1);
n++;
}
/* FIXME: remove the following when the lavc SubRip decoder is fixed
* (trailing tags are not correctly flushed, see what happens to FATE when
* you disable this code) */
if (buf->len)
av_bprintf(buf, "\n");
}
static int srt_read_packet(AVFormatContext *s, AVPacket *pkt)
{
AVBPrint buf;
int64_t pos = avio_tell(s->pb);
int res = AVERROR_EOF;
av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
read_chunk(s->pb, &buf);
if (buf.len) {
int64_t pts;
int duration, pkt_size;
const char *ptr = buf.str;
int32_t x1 = -1, y1 = -1, x2 = -1, y2 = -1;
pts = get_pts(&ptr, &duration, &x1, &y1, &x2, &y2);
pkt_size = buf.len - (ptr - buf.str);
if (pts != AV_NOPTS_VALUE && !(res = av_new_packet(pkt, pkt_size))) {
memcpy(pkt->data, ptr, pkt->size);
pkt->flags |= AV_PKT_FLAG_KEY;
pkt->pos = pos;
pkt->pts = pkt->dts = pts;
pkt->duration = duration;
if (x1 != -1) {
uint8_t *p = av_packet_new_side_data(pkt, AV_PKT_DATA_SUBTITLE_POSITION, 16);
if (p) {
AV_WL32(p, x1);
AV_WL32(p + 4, y1);
AV_WL32(p + 8, x2);
AV_WL32(p + 12, y2);
}
}
}
}
av_bprint_finalize(&buf, NULL);
return res;
}
AVInputFormat ff_srt_demuxer = {
.name = "srt",
.long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
.read_probe = srt_probe,
.read_header = srt_read_header,
.read_packet = srt_read_packet,
.flags = AVFMT_GENERIC_INDEX,
};