1 /*
2 * XSUB subtitle decoder
3 * Copyright (c) 2007 Reimar Döffinger
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg 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.
11 *
12 * FFmpeg 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.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavutil/mathematics.h"
23 #include "libavutil/imgutils.h"
24 #include "avcodec.h"
25 #include "get_bits.h"
26 #include "bytestream.h"
27 #include "internal.h"
28
decode_init(AVCodecContext * avctx)29 static av_cold int decode_init(AVCodecContext *avctx) {
30 avctx->pix_fmt = AV_PIX_FMT_PAL8;
31 return 0;
32 }
33
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 };
36
parse_timecode(const uint8_t * buf,int64_t packet_time)37 static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
38 int i;
39 int64_t ms = 0;
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];
46 }
47 return ms - packet_time;
48 }
49
decode_frame(AVCodecContext * avctx,void * data,int * got_sub_ptr,AVPacket * avpkt)50 static int decode_frame(AVCodecContext *avctx, void *data, int *got_sub_ptr,
51 AVPacket *avpkt) {
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;
56 uint8_t *bitmap;
57 int w, h, x, y, i, ret;
58 int64_t packet_time = 0;
59 GetBitContext gb;
60 int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
61
62 // check that at least header fits
63 if (buf_size < 27 + 7 * 2 + 4 * (3 + has_alpha)) {
64 av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size);
65 return -1;
66 }
67
68 // read start and end time
69 if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
70 av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
71 return -1;
72 }
73 if (avpkt->pts != AV_NOPTS_VALUE)
74 packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
75 sub->start_display_time = parse_timecode(buf + 1, packet_time);
76 sub->end_display_time = parse_timecode(buf + 14, packet_time);
77 buf += 27;
78
79 // read header
80 w = bytestream_get_le16(&buf);
81 h = bytestream_get_le16(&buf);
82 if (av_image_check_size(w, h, 0, avctx) < 0)
83 return -1;
84 x = bytestream_get_le16(&buf);
85 y = bytestream_get_le16(&buf);
86 // skip bottom right position, it gives no new information
87 bytestream_get_le16(&buf);
88 bytestream_get_le16(&buf);
89 // The following value is supposed to indicate the start offset
90 // (relative to the palette) of the data for the second field,
91 // however there are files in which it has a bogus value and thus
92 // we just ignore it
93 bytestream_get_le16(&buf);
94
95 if (buf_end - buf < h + 3*4)
96 return AVERROR_INVALIDDATA;
97
98 // allocate sub and set values
99 sub->rects = av_mallocz(sizeof(*sub->rects));
100 if (!sub->rects)
101 return AVERROR(ENOMEM);
102
103 sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
104 if (!sub->rects[0]) {
105 av_freep(&sub->rects);
106 return AVERROR(ENOMEM);
107 }
108 sub->rects[0]->x = x; sub->rects[0]->y = y;
109 sub->rects[0]->w = w; sub->rects[0]->h = h;
110 sub->rects[0]->type = SUBTITLE_BITMAP;
111 sub->rects[0]->linesize[0] = w;
112 sub->rects[0]->data[0] = av_malloc(w * h);
113 sub->rects[0]->nb_colors = 4;
114 sub->rects[0]->data[1] = av_mallocz(AVPALETTE_SIZE);
115 if (!sub->rects[0]->data[0] || !sub->rects[0]->data[1]) {
116 av_freep(&sub->rects[0]->data[1]);
117 av_freep(&sub->rects[0]->data[0]);
118 av_freep(&sub->rects[0]);
119 av_freep(&sub->rects);
120 return AVERROR(ENOMEM);
121 }
122 sub->num_rects = 1;
123
124 // read palette
125 for (i = 0; i < sub->rects[0]->nb_colors; i++)
126 ((uint32_t*)sub->rects[0]->data[1])[i] = bytestream_get_be24(&buf);
127
128 if (!has_alpha) {
129 // make all except background (first entry) non-transparent
130 for (i = 1; i < sub->rects[0]->nb_colors; i++)
131 ((uint32_t *)sub->rects[0]->data[1])[i] |= 0xff000000;
132 } else {
133 for (i = 0; i < sub->rects[0]->nb_colors; i++)
134 ((uint32_t *)sub->rects[0]->data[1])[i] |= (unsigned)*buf++ << 24;
135 }
136
137 #if FF_API_AVPICTURE
138 FF_DISABLE_DEPRECATION_WARNINGS
139 {
140 AVSubtitleRect *rect;
141 int j;
142 rect = sub->rects[0];
143 for (j = 0; j < 4; j++) {
144 rect->pict.data[j] = rect->data[j];
145 rect->pict.linesize[j] = rect->linesize[j];
146 }
147 }
148 FF_ENABLE_DEPRECATION_WARNINGS
149 #endif
150
151 // process RLE-compressed data
152 if ((ret = init_get_bits8(&gb, buf, buf_end - buf)) < 0)
153 return ret;
154 bitmap = sub->rects[0]->data[0];
155 for (y = 0; y < h; y++) {
156 // interlaced: do odd lines
157 if (y == (h + 1) / 2) bitmap = sub->rects[0]->data[0] + w;
158 for (x = 0; x < w; ) {
159 int log2 = ff_log2_tab[show_bits(&gb, 8)];
160 int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
161 int color = get_bits(&gb, 2);
162 run = FFMIN(run, w - x);
163 // run length 0 means till end of row
164 if (!run) run = w - x;
165 memset(bitmap, color, run);
166 bitmap += run;
167 x += run;
168 }
169 // interlaced, skip every second line
170 bitmap += w;
171 align_get_bits(&gb);
172 }
173 *got_sub_ptr = 1;
174 return buf_size;
175 }
176
177 AVCodec ff_xsub_decoder = {
178 .name = "xsub",
179 .long_name = NULL_IF_CONFIG_SMALL("XSUB"),
180 .type = AVMEDIA_TYPE_SUBTITLE,
181 .id = AV_CODEC_ID_XSUB,
182 .init = decode_init,
183 .decode = decode_frame,
184 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
185 };
186