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1 | /* |
2 | * DivX (XSUB) subtitle encoder | |
3 | * Copyright (c) 2005 DivX, Inc. | |
4 | * Copyright (c) 2009 Bjorn Axelsson | |
5 | * | |
6 | * This file is part of FFmpeg. | |
7 | * | |
8 | * FFmpeg is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * FFmpeg is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with FFmpeg; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
23 | #include "avcodec.h" | |
24 | #include "bytestream.h" | |
25 | #include "put_bits.h" | |
26 | ||
27 | /** | |
28 | * Number of pixels to pad left and right. | |
29 | * | |
30 | * The official encoder pads the subtitles with two pixels on either side, | |
31 | * but until we find out why, we won't do it (we will pad to have width | |
32 | * divisible by 2 though). | |
33 | */ | |
34 | #define PADDING 0 | |
35 | #define PADDING_COLOR 0 | |
36 | ||
37 | /** | |
38 | * Encode a single color run. At most 16 bits will be used. | |
39 | * @param len length of the run, values > 255 mean "until end of line", may not be < 0. | |
40 | * @param color color to encode, only the lowest two bits are used and all others must be 0. | |
41 | */ | |
42 | static void put_xsub_rle(PutBitContext *pb, int len, int color) | |
43 | { | |
44 | if (len <= 255) | |
45 | put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len); | |
46 | else | |
47 | put_bits(pb, 14, 0); | |
48 | put_bits(pb, 2, color); | |
49 | } | |
50 | ||
51 | /** | |
52 | * Encode a 4-color bitmap with XSUB rle. | |
53 | * | |
54 | * The encoded bitmap may be wider than the source bitmap due to padding. | |
55 | */ | |
56 | static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap, | |
57 | int linesize, int w, int h) | |
58 | { | |
59 | int x0, x1, y, len, color = PADDING_COLOR; | |
60 | ||
61 | for (y = 0; y < h; y++) { | |
62 | x0 = 0; | |
63 | while (x0 < w) { | |
64 | // Make sure we have enough room for at least one run and padding | |
65 | if (pb->size_in_bits - put_bits_count(pb) < 7*8) | |
66 | return -1; | |
67 | ||
68 | x1 = x0; | |
69 | color = bitmap[x1++] & 3; | |
70 | while (x1 < w && (bitmap[x1] & 3) == color) | |
71 | x1++; | |
72 | len = x1 - x0; | |
73 | if (PADDING && x0 == 0) { | |
74 | if (color == PADDING_COLOR) { | |
75 | len += PADDING; | |
76 | x0 -= PADDING; | |
77 | } else | |
78 | put_xsub_rle(pb, PADDING, PADDING_COLOR); | |
79 | } | |
80 | ||
81 | // Run can't be longer than 255, unless it is the rest of a row | |
82 | if (x1 == w && color == PADDING_COLOR) { | |
83 | len += PADDING + (w&1); | |
84 | } else | |
85 | len = FFMIN(len, 255); | |
86 | put_xsub_rle(pb, len, color); | |
87 | ||
88 | x0 += len; | |
89 | } | |
90 | if (color != PADDING_COLOR && (PADDING + (w&1))) | |
91 | put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR); | |
92 | ||
93 | avpriv_align_put_bits(pb); | |
94 | ||
95 | bitmap += linesize; | |
96 | } | |
97 | ||
98 | return 0; | |
99 | } | |
100 | ||
101 | static int make_tc(uint64_t ms, int *tc) | |
102 | { | |
103 | static const int tc_divs[3] = { 1000, 60, 60 }; | |
104 | int i; | |
105 | for (i=0; i<3; i++) { | |
106 | tc[i] = ms % tc_divs[i]; | |
107 | ms /= tc_divs[i]; | |
108 | } | |
109 | tc[3] = ms; | |
110 | return ms > 99; | |
111 | } | |
112 | ||
113 | static int xsub_encode(AVCodecContext *avctx, unsigned char *buf, | |
114 | int bufsize, const AVSubtitle *h) | |
115 | { | |
116 | uint64_t startTime = h->pts / 1000; // FIXME: need better solution... | |
117 | uint64_t endTime = startTime + h->end_display_time - h->start_display_time; | |
118 | int start_tc[4], end_tc[4]; | |
119 | uint8_t *hdr = buf + 27; // Point behind the timestamp | |
120 | uint8_t *rlelenptr; | |
121 | uint16_t width, height; | |
122 | int i; | |
123 | PutBitContext pb; | |
124 | ||
125 | if (bufsize < 27 + 7*2 + 4*3) { | |
126 | av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n"); | |
127 | return -1; | |
128 | } | |
129 | ||
130 | // TODO: support multiple rects | |
131 | if (h->num_rects != 1) | |
132 | av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects); | |
133 | ||
134 | // TODO: render text-based subtitles into bitmaps | |
135 | if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) { | |
136 | av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n"); | |
137 | return -1; | |
138 | } | |
139 | ||
140 | // TODO: color reduction, similar to dvdsub encoder | |
141 | if (h->rects[0]->nb_colors > 4) | |
142 | av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors); | |
143 | ||
144 | // TODO: Palette swapping if color zero is not transparent | |
145 | if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff000000) | |
146 | av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n"); | |
147 | ||
148 | if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) { | |
149 | av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n"); | |
150 | return -1; | |
151 | } | |
152 | ||
153 | snprintf(buf, 28, | |
154 | "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]", | |
155 | start_tc[3], start_tc[2], start_tc[1], start_tc[0], | |
156 | end_tc[3], end_tc[2], end_tc[1], end_tc[0]); | |
157 | ||
158 | // Width and height must probably be multiples of 2. | |
159 | // 2 pixels required on either side of subtitle. | |
160 | // Possibly due to limitations of hardware renderers. | |
161 | // TODO: check if the bitmap is already padded | |
162 | width = FFALIGN(h->rects[0]->w, 2) + PADDING * 2; | |
163 | height = FFALIGN(h->rects[0]->h, 2); | |
164 | ||
165 | bytestream_put_le16(&hdr, width); | |
166 | bytestream_put_le16(&hdr, height); | |
167 | bytestream_put_le16(&hdr, h->rects[0]->x); | |
168 | bytestream_put_le16(&hdr, h->rects[0]->y); | |
169 | bytestream_put_le16(&hdr, h->rects[0]->x + width -1); | |
170 | bytestream_put_le16(&hdr, h->rects[0]->y + height -1); | |
171 | ||
172 | rlelenptr = hdr; // Will store length of first field here later. | |
173 | hdr+=2; | |
174 | ||
175 | // Palette | |
176 | for (i=0; i<4; i++) | |
177 | bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]); | |
178 | ||
179 | // Bitmap | |
180 | // RLE buffer. Reserve 2 bytes for possible padding after the last row. | |
181 | init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2); | |
182 | if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0], | |
183 | h->rects[0]->pict.linesize[0]*2, | |
184 | h->rects[0]->w, (h->rects[0]->h + 1) >> 1)) | |
185 | return -1; | |
186 | bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field | |
187 | ||
188 | if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0], | |
189 | h->rects[0]->pict.linesize[0]*2, | |
190 | h->rects[0]->w, h->rects[0]->h >> 1)) | |
191 | return -1; | |
192 | ||
193 | // Enforce total height to be a multiple of 2 | |
194 | if (h->rects[0]->h & 1) { | |
195 | put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR); | |
196 | avpriv_align_put_bits(&pb); | |
197 | } | |
198 | ||
199 | flush_put_bits(&pb); | |
200 | ||
201 | return hdr - buf + put_bits_count(&pb)/8; | |
202 | } | |
203 | ||
204 | static av_cold int xsub_encoder_init(AVCodecContext *avctx) | |
205 | { | |
206 | if (!avctx->codec_tag) | |
207 | avctx->codec_tag = MKTAG('D','X','S','B'); | |
208 | ||
209 | avctx->bits_per_coded_sample = 4; | |
210 | ||
211 | return 0; | |
212 | } | |
213 | ||
214 | AVCodec ff_xsub_encoder = { | |
215 | .name = "xsub", | |
216 | .long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"), | |
217 | .type = AVMEDIA_TYPE_SUBTITLE, | |
218 | .id = AV_CODEC_ID_XSUB, | |
219 | .init = xsub_encoder_init, | |
220 | .encode_sub = xsub_encode, | |
221 | }; |