71c5e792d0d177eae774a87bdd51bccfd4abb526
[libav.git] / libavcodec / dvdsubenc.c
1 /*
2 * DVD subtitle encoding for ffmpeg
3 * Copyright (c) 2005 Wolfram Gloger
4 *
5 * This file is part of Libav.
6 *
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.
11 *
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.
16 *
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
20 */
21 #include "avcodec.h"
22 #include "bytestream.h"
23
24 #undef NDEBUG
25 #include <assert.h>
26
27 // ncnt is the nibble counter
28 #define PUTNIBBLE(val)\
29 do {\
30 if (ncnt++ & 1)\
31 *q++ = bitbuf | ((val) & 0x0f);\
32 else\
33 bitbuf = (val) << 4;\
34 } while(0)
35
36 static void dvd_encode_rle(uint8_t **pq,
37 const uint8_t *bitmap, int linesize,
38 int w, int h,
39 const int cmap[256])
40 {
41 uint8_t *q;
42 unsigned int bitbuf = 0;
43 int ncnt;
44 int x, y, len, color;
45
46 q = *pq;
47
48 for (y = 0; y < h; ++y) {
49 ncnt = 0;
50 for(x = 0; x < w; x += len) {
51 color = bitmap[x];
52 for (len=1; x+len < w; ++len)
53 if (bitmap[x+len] != color)
54 break;
55 color = cmap[color];
56 assert(color < 4);
57 if (len < 0x04) {
58 PUTNIBBLE((len << 2)|color);
59 } else if (len < 0x10) {
60 PUTNIBBLE(len >> 2);
61 PUTNIBBLE((len << 2)|color);
62 } else if (len < 0x40) {
63 PUTNIBBLE(0);
64 PUTNIBBLE(len >> 2);
65 PUTNIBBLE((len << 2)|color);
66 } else if (x+len == w) {
67 PUTNIBBLE(0);
68 PUTNIBBLE(0);
69 PUTNIBBLE(0);
70 PUTNIBBLE(color);
71 } else {
72 if (len > 0xff)
73 len = 0xff;
74 PUTNIBBLE(0);
75 PUTNIBBLE(len >> 6);
76 PUTNIBBLE(len >> 2);
77 PUTNIBBLE((len << 2)|color);
78 }
79 }
80 /* end of line */
81 if (ncnt & 1)
82 PUTNIBBLE(0);
83 bitmap += linesize;
84 }
85
86 *pq = q;
87 }
88
89 static int encode_dvd_subtitles(uint8_t *outbuf, int outbuf_size,
90 const AVSubtitle *h)
91 {
92 uint8_t *q, *qq;
93 int object_id;
94 int offset1[20], offset2[20];
95 int i, imax, color, alpha, rects = h->num_rects;
96 unsigned long hmax;
97 unsigned long hist[256];
98 int cmap[256];
99
100 if (rects == 0 || h->rects == NULL)
101 return -1;
102 if (rects > 20)
103 rects = 20;
104
105 // analyze bitmaps, compress to 4 colors
106 for (i=0; i<256; ++i) {
107 hist[i] = 0;
108 cmap[i] = 0;
109 }
110 for (object_id = 0; object_id < rects; object_id++)
111 for (i=0; i<h->rects[object_id]->w*h->rects[object_id]->h; ++i) {
112 color = h->rects[object_id]->pict.data[0][i];
113 // only count non-transparent pixels
114 alpha = ((uint32_t*)h->rects[object_id]->pict.data[1])[color] >> 24;
115 hist[color] += alpha;
116 }
117 for (color=3;; --color) {
118 hmax = 0;
119 imax = 0;
120 for (i=0; i<256; ++i)
121 if (hist[i] > hmax) {
122 imax = i;
123 hmax = hist[i];
124 }
125 if (hmax == 0)
126 break;
127 if (color == 0)
128 color = 3;
129 av_log(NULL, AV_LOG_DEBUG, "dvd_subtitle hist[%d]=%ld -> col %d\n",
130 imax, hist[imax], color);
131 cmap[imax] = color;
132 hist[imax] = 0;
133 }
134
135
136 // encode data block
137 q = outbuf + 4;
138 for (object_id = 0; object_id < rects; object_id++) {
139 offset1[object_id] = q - outbuf;
140 // worst case memory requirement: 1 nibble per pixel..
141 if ((q - outbuf) + h->rects[object_id]->w*h->rects[object_id]->h/2
142 + 17*rects + 21 > outbuf_size) {
143 av_log(NULL, AV_LOG_ERROR, "dvd_subtitle too big\n");
144 return -1;
145 }
146 dvd_encode_rle(&q, h->rects[object_id]->pict.data[0],
147 h->rects[object_id]->w*2,
148 h->rects[object_id]->w, h->rects[object_id]->h >> 1,
149 cmap);
150 offset2[object_id] = q - outbuf;
151 dvd_encode_rle(&q, h->rects[object_id]->pict.data[0] + h->rects[object_id]->w,
152 h->rects[object_id]->w*2,
153 h->rects[object_id]->w, h->rects[object_id]->h >> 1,
154 cmap);
155 }
156
157 // set data packet size
158 qq = outbuf + 2;
159 bytestream_put_be16(&qq, q - outbuf);
160
161 // send start display command
162 bytestream_put_be16(&q, (h->start_display_time*90) >> 10);
163 bytestream_put_be16(&q, (q - outbuf) /*- 2 */ + 8 + 12*rects + 2);
164 *q++ = 0x03; // palette - 4 nibbles
165 *q++ = 0x03; *q++ = 0x7f;
166 *q++ = 0x04; // alpha - 4 nibbles
167 *q++ = 0xf0; *q++ = 0x00;
168 //*q++ = 0x0f; *q++ = 0xff;
169
170 // XXX not sure if more than one rect can really be encoded..
171 // 12 bytes per rect
172 for (object_id = 0; object_id < rects; object_id++) {
173 int x2 = h->rects[object_id]->x + h->rects[object_id]->w - 1;
174 int y2 = h->rects[object_id]->y + h->rects[object_id]->h - 1;
175
176 *q++ = 0x05;
177 // x1 x2 -> 6 nibbles
178 *q++ = h->rects[object_id]->x >> 4;
179 *q++ = (h->rects[object_id]->x << 4) | ((x2 >> 8) & 0xf);
180 *q++ = x2;
181 // y1 y2 -> 6 nibbles
182 *q++ = h->rects[object_id]->y >> 4;
183 *q++ = (h->rects[object_id]->y << 4) | ((y2 >> 8) & 0xf);
184 *q++ = y2;
185
186 *q++ = 0x06;
187 // offset1, offset2
188 bytestream_put_be16(&q, offset1[object_id]);
189 bytestream_put_be16(&q, offset2[object_id]);
190 }
191 *q++ = 0x01; // start command
192 *q++ = 0xff; // terminating command
193
194 // send stop display command last
195 bytestream_put_be16(&q, (h->end_display_time*90) >> 10);
196 bytestream_put_be16(&q, (q - outbuf) - 2 /*+ 4*/);
197 *q++ = 0x02; // set end
198 *q++ = 0xff; // terminating command
199
200 qq = outbuf;
201 bytestream_put_be16(&qq, q - outbuf);
202
203 av_log(NULL, AV_LOG_DEBUG, "subtitle_packet size=%td\n", q - outbuf);
204 return q - outbuf;
205 }
206
207 static int dvdsub_encode(AVCodecContext *avctx,
208 unsigned char *buf, int buf_size, void *data)
209 {
210 //DVDSubtitleContext *s = avctx->priv_data;
211 AVSubtitle *sub = data;
212 int ret;
213
214 ret = encode_dvd_subtitles(buf, buf_size, sub);
215 return ret;
216 }
217
218 AVCodec ff_dvdsub_encoder = {
219 "dvdsub",
220 AVMEDIA_TYPE_SUBTITLE,
221 CODEC_ID_DVD_SUBTITLE,
222 0,
223 NULL,
224 dvdsub_encode,
225 .long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
226 };