5f6bc21ac893768ca389f8cb1ef30a28fbde8a49
[ffmpeg.git] / libavcodec / dvdsubenc.c
1 /*
2  * DVD subtitle encoding for ffmpeg
3  * Copyright (c) 2005 Wolfram Gloger.
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 #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 dvdsub_encoder = {
219     "dvdsub",
220     CODEC_TYPE_SUBTITLE,
221     CODEC_ID_DVD_SUBTITLE,
222     0,
223     NULL,
224     dvdsub_encode,
225     .long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
226 };