2 * XSUB subtitle decoder
3 * Copyright (c) 2007 Reimar Döffinger
5 * This file is part of Libav.
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * Libav is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 #include "libavutil/mathematics.h"
23 #include "libavutil/imgutils.h"
26 #include "bitstream.h"
27 #include "bytestream.h"
29 static av_cold int decode_init(AVCodecContext *avctx) {
30 avctx->pix_fmt = AV_PIX_FMT_PAL8;
34 static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
35 static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };
37 static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
40 if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
41 return AV_NOPTS_VALUE;
42 for (i = 0; i < sizeof(tc_offsets); i++) {
43 uint8_t c = buf[tc_offsets[i]] - '0';
44 if (c > 9) return AV_NOPTS_VALUE;
45 ms = (ms + c) * tc_muls[i];
47 return ms - packet_time;
50 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
52 const uint8_t *buf = avpkt->data;
53 int buf_size = avpkt->size;
54 AVSubtitle *sub = data;
55 const uint8_t *buf_end = buf + buf_size;
58 int64_t packet_time = 0;
60 int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
62 memset(sub, 0, sizeof(*sub));
64 // check that at least header fits
65 if (buf_size < 27 + 7 * 2 + 4 * (3 + has_alpha)) {
66 av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
70 // read start and end time
71 if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
72 av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
75 if (avpkt->pts != AV_NOPTS_VALUE)
76 packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
77 sub->start_display_time = parse_timecode(buf + 1, packet_time);
78 sub->end_display_time = parse_timecode(buf + 14, packet_time);
82 w = bytestream_get_le16(&buf);
83 h = bytestream_get_le16(&buf);
84 if (av_image_check_size(w, h, 0, avctx) < 0)
86 x = bytestream_get_le16(&buf);
87 y = bytestream_get_le16(&buf);
88 // skip bottom right position, it gives no new information
89 bytestream_get_le16(&buf);
90 bytestream_get_le16(&buf);
91 // The following value is supposed to indicate the start offset
92 // (relative to the palette) of the data for the second field,
93 // however there are files in which it has a bogus value and thus
95 bytestream_get_le16(&buf);
97 // allocate sub and set values
98 sub->rects = av_mallocz(sizeof(*sub->rects));
100 return AVERROR(ENOMEM);
101 sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
102 if (!sub->rects[0]) {
103 av_freep(&sub->rects);
104 return AVERROR(ENOMEM);
107 sub->rects[0]->x = x; sub->rects[0]->y = y;
108 sub->rects[0]->w = w; sub->rects[0]->h = h;
109 sub->rects[0]->type = SUBTITLE_BITMAP;
110 sub->rects[0]->linesize[0] = w;
111 sub->rects[0]->data[0] = av_malloc(w * h);
112 sub->rects[0]->nb_colors = 4;
113 sub->rects[0]->data[1] = av_mallocz(AVPALETTE_SIZE);
114 if (!sub->rects[0]->data[0] || !sub->rects[0]->data[1]) {
115 av_freep(&sub->rects[0]->data[1]);
116 av_freep(&sub->rects[0]->data[0]);
117 av_freep(&sub->rects[0]);
118 av_freep(&sub->rects);
119 return AVERROR(ENOMEM);
123 for (i = 0; i < sub->rects[0]->nb_colors; i++)
124 ((uint32_t*)sub->rects[0]->data[1])[i] = bytestream_get_be24(&buf);
127 // make all except background (first entry) non-transparent
128 for (i = 1; i < sub->rects[0]->nb_colors; i++)
129 ((uint32_t *)sub->rects[0]->data[1])[i] |= 0xff000000;
131 for (i = 0; i < sub->rects[0]->nb_colors; i++)
132 ((uint32_t *)sub->rects[0]->data[1])[i] |= *buf++ << 24;
136 FF_DISABLE_DEPRECATION_WARNINGS
138 AVSubtitleRect *rect;
140 rect = sub->rects[0];
141 for (j = 0; j < 4; j++) {
142 rect->pict.data[j] = rect->data[j];
143 rect->pict.linesize[j] = rect->linesize[j];
146 FF_ENABLE_DEPRECATION_WARNINGS
149 // process RLE-compressed data
150 bitstream_init8(&bc, buf, buf_end - buf);
151 bitmap = sub->rects[0]->data[0];
152 for (y = 0; y < h; y++) {
153 // interlaced: do odd lines
154 if (y == (h + 1) / 2) bitmap = sub->rects[0]->data[0] + w;
155 for (x = 0; x < w; ) {
156 int log2 = ff_log2_tab[bitstream_peek(&bc, 8)];
157 int run = bitstream_read(&bc, 14 - 4 * (log2 >> 1));
158 int color = bitstream_read(&bc, 2);
159 run = FFMIN(run, w - x);
160 // run length 0 means till end of row
161 if (!run) run = w - x;
162 memset(bitmap, color, run);
166 // interlaced, skip every second line
168 bitstream_align(&bc);
174 AVCodec ff_xsub_decoder = {
176 .long_name = NULL_IF_CONFIG_SMALL("XSUB"),
177 .type = AVMEDIA_TYPE_SUBTITLE,
178 .id = AV_CODEC_ID_XSUB,
180 .decode = decode_frame,