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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 | ||
28 | static av_cold int decode_init(AVCodecContext *avctx) { | |
29 | avctx->pix_fmt = AV_PIX_FMT_PAL8; | |
30 | return 0; | |
31 | } | |
32 | ||
33 | static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 }; | |
34 | static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 }; | |
35 | ||
36 | static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) { | |
37 | int i; | |
38 | int64_t ms = 0; | |
39 | if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.') | |
40 | return AV_NOPTS_VALUE; | |
41 | for (i = 0; i < sizeof(tc_offsets); i++) { | |
42 | uint8_t c = buf[tc_offsets[i]] - '0'; | |
43 | if (c > 9) return AV_NOPTS_VALUE; | |
44 | ms = (ms + c) * tc_muls[i]; | |
45 | } | |
46 | return ms - packet_time; | |
47 | } | |
48 | ||
49 | static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, | |
50 | AVPacket *avpkt) { | |
51 | const uint8_t *buf = avpkt->data; | |
52 | int buf_size = avpkt->size; | |
53 | AVSubtitle *sub = data; | |
54 | const uint8_t *buf_end = buf + buf_size; | |
55 | uint8_t *bitmap; | |
56 | int w, h, x, y, i; | |
57 | int64_t packet_time = 0; | |
58 | GetBitContext gb; | |
59 | int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A'); | |
60 | ||
61 | // check that at least header fits | |
62 | if (buf_size < 27 + 7 * 2 + 4 * 3) { | |
63 | av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size); | |
64 | return -1; | |
65 | } | |
66 | ||
67 | // read start and end time | |
68 | if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') { | |
69 | av_log(avctx, AV_LOG_ERROR, "invalid time code\n"); | |
70 | return -1; | |
71 | } | |
72 | if (avpkt->pts != AV_NOPTS_VALUE) | |
73 | packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000}); | |
74 | sub->start_display_time = parse_timecode(buf + 1, packet_time); | |
75 | sub->end_display_time = parse_timecode(buf + 14, packet_time); | |
76 | buf += 27; | |
77 | ||
78 | // read header | |
79 | w = bytestream_get_le16(&buf); | |
80 | h = bytestream_get_le16(&buf); | |
81 | if (av_image_check_size(w, h, 0, avctx) < 0) | |
82 | return -1; | |
83 | x = bytestream_get_le16(&buf); | |
84 | y = bytestream_get_le16(&buf); | |
85 | // skip bottom right position, it gives no new information | |
86 | bytestream_get_le16(&buf); | |
87 | bytestream_get_le16(&buf); | |
88 | // The following value is supposed to indicate the start offset | |
89 | // (relative to the palette) of the data for the second field, | |
90 | // however there are files in which it has a bogus value and thus | |
91 | // we just ignore it | |
92 | bytestream_get_le16(&buf); | |
93 | ||
94 | // allocate sub and set values | |
95 | sub->rects = av_mallocz(sizeof(*sub->rects)); | |
96 | sub->rects[0] = av_mallocz(sizeof(*sub->rects[0])); | |
97 | sub->num_rects = 1; | |
98 | sub->rects[0]->x = x; sub->rects[0]->y = y; | |
99 | sub->rects[0]->w = w; sub->rects[0]->h = h; | |
100 | sub->rects[0]->type = SUBTITLE_BITMAP; | |
101 | sub->rects[0]->pict.linesize[0] = w; | |
102 | sub->rects[0]->pict.data[0] = av_malloc(w * h); | |
103 | sub->rects[0]->nb_colors = 4; | |
104 | sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE); | |
105 | ||
106 | // read palette | |
107 | for (i = 0; i < sub->rects[0]->nb_colors; i++) | |
108 | ((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf); | |
109 | // make all except background (first entry) non-transparent | |
110 | for (i = 0; i < sub->rects[0]->nb_colors; i++) | |
111 | ((uint32_t*)sub->rects[0]->pict.data[1])[i] |= (has_alpha ? *buf++ : (i ? 0xff : 0)) << 24; | |
112 | ||
113 | // process RLE-compressed data | |
114 | init_get_bits(&gb, buf, (buf_end - buf) * 8); | |
115 | bitmap = sub->rects[0]->pict.data[0]; | |
116 | for (y = 0; y < h; y++) { | |
117 | // interlaced: do odd lines | |
118 | if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w; | |
119 | for (x = 0; x < w; ) { | |
120 | int log2 = ff_log2_tab[show_bits(&gb, 8)]; | |
121 | int run = get_bits(&gb, 14 - 4 * (log2 >> 1)); | |
122 | int color = get_bits(&gb, 2); | |
123 | run = FFMIN(run, w - x); | |
124 | // run length 0 means till end of row | |
125 | if (!run) run = w - x; | |
126 | memset(bitmap, color, run); | |
127 | bitmap += run; | |
128 | x += run; | |
129 | } | |
130 | // interlaced, skip every second line | |
131 | bitmap += w; | |
132 | align_get_bits(&gb); | |
133 | } | |
134 | *data_size = 1; | |
135 | return buf_size; | |
136 | } | |
137 | ||
138 | AVCodec ff_xsub_decoder = { | |
139 | .name = "xsub", | |
140 | .long_name = NULL_IF_CONFIG_SMALL("XSUB"), | |
141 | .type = AVMEDIA_TYPE_SUBTITLE, | |
142 | .id = AV_CODEC_ID_XSUB, | |
143 | .init = decode_init, | |
144 | .decode = decode_frame, | |
145 | }; |