FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/xsubdec.c
Date: 2024-04-12 08:31:17
Exec Total Coverage
Lines: 0 81 0.0%
Functions: 0 3 0.0%
Branches: 0 50 0.0%

Line Branch Exec Source
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 "libavutil/mem.h"
25 #include "avcodec.h"
26 #include "get_bits.h"
27 #include "bytestream.h"
28 #include "codec_internal.h"
29
30 static av_cold int decode_init(AVCodecContext *avctx) {
31 avctx->pix_fmt = AV_PIX_FMT_PAL8;
32 return 0;
33 }
34
35 static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
36 static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };
37
38 static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
39 int i;
40 int64_t ms = 0;
41 if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
42 return AV_NOPTS_VALUE;
43 for (i = 0; i < sizeof(tc_offsets); i++) {
44 uint8_t c = buf[tc_offsets[i]] - '0';
45 if (c > 9) return AV_NOPTS_VALUE;
46 ms = (ms + c) * tc_muls[i];
47 }
48 return ms - packet_time;
49 }
50
51 static int decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
52 int *got_sub_ptr, const AVPacket *avpkt)
53 {
54 const uint8_t *buf = avpkt->data;
55 int buf_size = avpkt->size;
56 AVSubtitleRect *rect;
57 const uint8_t *buf_end = buf + buf_size;
58 uint8_t *bitmap;
59 int w, h, x, y, i, ret;
60 int64_t packet_time = 0;
61 GetBitContext gb;
62 int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
63
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 size %d too small\n", buf_size);
67 return -1;
68 }
69
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");
73 return -1;
74 }
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);
79 buf += 27;
80
81 // read header
82 w = bytestream_get_le16(&buf);
83 h = bytestream_get_le16(&buf);
84 if (av_image_check_size(w, h, 0, avctx) < 0)
85 return -1;
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
94 // we just ignore it
95 bytestream_get_le16(&buf);
96
97 if (buf_end - buf < h + 3*4)
98 return AVERROR_INVALIDDATA;
99
100 // allocate sub and set values
101 sub->rects = av_mallocz(sizeof(*sub->rects));
102 if (!sub->rects)
103 return AVERROR(ENOMEM);
104
105 sub->rects[0] = rect = av_mallocz(sizeof(*sub->rects[0]));
106 if (!sub->rects[0])
107 return AVERROR(ENOMEM);
108 sub->num_rects = 1;
109 rect->x = x; rect->y = y;
110 rect->w = w; rect->h = h;
111 rect->type = SUBTITLE_BITMAP;
112 rect->linesize[0] = w;
113 rect->data[0] = av_malloc(w * h);
114 rect->nb_colors = 4;
115 rect->data[1] = av_mallocz(AVPALETTE_SIZE);
116 if (!rect->data[0] || !rect->data[1])
117 return AVERROR(ENOMEM);
118
119 // read palette
120 for (i = 0; i < rect->nb_colors; i++)
121 ((uint32_t*)rect->data[1])[i] = bytestream_get_be24(&buf);
122
123 if (!has_alpha) {
124 // make all except background (first entry) non-transparent
125 for (i = 1; i < rect->nb_colors; i++)
126 ((uint32_t *)rect->data[1])[i] |= 0xff000000;
127 } else {
128 for (i = 0; i < rect->nb_colors; i++)
129 ((uint32_t *)rect->data[1])[i] |= (unsigned)*buf++ << 24;
130 }
131
132 // process RLE-compressed data
133 if ((ret = init_get_bits8(&gb, buf, buf_end - buf)) < 0)
134 return ret;
135 bitmap = rect->data[0];
136 for (y = 0; y < h; y++) {
137 // interlaced: do odd lines
138 if (y == (h + 1) / 2) bitmap = rect->data[0] + w;
139 for (x = 0; x < w; ) {
140 int log2 = ff_log2_tab[show_bits(&gb, 8)];
141 int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
142 int color = get_bits(&gb, 2);
143 run = FFMIN(run, w - x);
144 // run length 0 means till end of row
145 if (!run) run = w - x;
146 memset(bitmap, color, run);
147 bitmap += run;
148 x += run;
149 }
150 // interlaced, skip every second line
151 bitmap += w;
152 align_get_bits(&gb);
153 }
154 *got_sub_ptr = 1;
155 return buf_size;
156 }
157
158 const FFCodec ff_xsub_decoder = {
159 .p.name = "xsub",
160 CODEC_LONG_NAME("XSUB"),
161 .p.type = AVMEDIA_TYPE_SUBTITLE,
162 .p.id = AV_CODEC_ID_XSUB,
163 .init = decode_init,
164 FF_CODEC_DECODE_SUB_CB(decode_frame),
165 };
166