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/*
* XSUB subtitle decoder
* Copyright (c) 2007 Reimar Döffinger
*
* 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 "libavutil/mathematics.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "get_bits.h"
#include "bytestream.h"
static av_cold int decode_init(AVCodecContext *avctx) {
avctx->pix_fmt = PIX_FMT_PAL8;
return 0;
}
static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };
static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
int i;
int64_t ms = 0;
if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
return AV_NOPTS_VALUE;
for (i = 0; i < sizeof(tc_offsets); i++) {
uint8_t c = buf[tc_offsets[i]] - '0';
if (c > 9) return AV_NOPTS_VALUE;
ms = (ms + c) * tc_muls[i];
}
return ms - packet_time;
}
static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
AVPacket *avpkt) {
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
AVSubtitle *sub = data;
const uint8_t *buf_end = buf + buf_size;
uint8_t *bitmap;
int w, h, x, y, i;
int64_t packet_time = 0;
GetBitContext gb;
int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
// check that at least header fits
if (buf_size < 27 + 7 * 2 + 4 * 3) {
av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
return -1;
}
// read start and end time
if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
return -1;
}
if (avpkt->pts != AV_NOPTS_VALUE)
packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
sub->start_display_time = parse_timecode(buf + 1, packet_time);
sub->end_display_time = parse_timecode(buf + 14, packet_time);
buf += 27;
// read header
w = bytestream_get_le16(&buf);
h = bytestream_get_le16(&buf);
if (av_image_check_size(w, h, 0, avctx) < 0)
return -1;
x = bytestream_get_le16(&buf);
y = bytestream_get_le16(&buf);
// skip bottom right position, it gives no new information
bytestream_get_le16(&buf);
bytestream_get_le16(&buf);
// The following value is supposed to indicate the start offset
// (relative to the palette) of the data for the second field,
// however there are files where it has a bogus value and thus
// we just ignore it
bytestream_get_le16(&buf);
// allocate sub and set values
sub->rects = av_mallocz(sizeof(*sub->rects));
sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
sub->num_rects = 1;
sub->rects[0]->x = x; sub->rects[0]->y = y;
sub->rects[0]->w = w; sub->rects[0]->h = h;
sub->rects[0]->type = SUBTITLE_BITMAP;
sub->rects[0]->pict.linesize[0] = w;
sub->rects[0]->pict.data[0] = av_malloc(w * h);
sub->rects[0]->nb_colors = 4;
sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
// read palette
for (i = 0; i < sub->rects[0]->nb_colors; i++)
((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf);
// make all except background (first entry) non-transparent
for (i = 0; i < sub->rects[0]->nb_colors; i++)
((uint32_t*)sub->rects[0]->pict.data[1])[i] |= (has_alpha ? *buf++ : (i ? 0xff : 0)) << 24;
// process RLE-compressed data
init_get_bits(&gb, buf, (buf_end - buf) * 8);
bitmap = sub->rects[0]->pict.data[0];
for (y = 0; y < h; y++) {
// interlaced: do odd lines
if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w;
for (x = 0; x < w; ) {
int log2 = ff_log2_tab[show_bits(&gb, 8)];
int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
int color = get_bits(&gb, 2);
run = FFMIN(run, w - x);
// run length 0 means till end of row
if (!run) run = w - x;
memset(bitmap, color, run);
bitmap += run;
x += run;
}
// interlaced, skip every second line
bitmap += w;
align_get_bits(&gb);
}
*data_size = 1;
return buf_size;
}
AVCodec ff_xsub_decoder = {
"xsub",
AVMEDIA_TYPE_SUBTITLE,
CODEC_ID_XSUB,
0,
decode_init,
NULL,
NULL,
decode_frame,
.long_name = NULL_IF_CONFIG_SMALL("XSUB"),
};
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