Statistics
| Branch: | Revision:

ffmpeg / libavformat / gif.c @ a8380f44

History | View | Annotate | Download (15.3 KB)

1
/*
2
 * Animated GIF encoder
3
 * Copyright (c) 2000 Fabrice Bellard.
4
 *
5
 * This library is free software; you can redistribute it and/or
6
 * modify it under the terms of the GNU Lesser General Public
7
 * License as published by the Free Software Foundation; either
8
 * version 2 of the License, or (at your option) any later version.
9
 *
10
 * This library is distributed in the hope that it will be useful,
11
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13
 * Lesser General Public License for more details.
14
 *
15
 * You should have received a copy of the GNU Lesser General Public
16
 * License along with this library; if not, write to the Free Software
17
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18
 */
19

    
20
/*
21
 * First version by Francois Revol revol@free.fr
22
 *
23
 * Features and limitations:
24
 * - currently no compression is performed,
25
 *   in fact the size of the data is 9/8 the size of the image in 8bpp
26
 * - uses only a global standard palette
27
 * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
28
 *
29
 * Reference documents:
30
 * http://www.goice.co.jp/member/mo/formats/gif.html
31
 * http://astronomy.swin.edu.au/pbourke/dataformats/gif/
32
 * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
33
 *
34
 * this url claims to have an LZW algorithm not covered by Unisys patent:
35
 * http://www.msg.net/utility/whirlgif/gifencod.html
36
 * could help reduce the size of the files _a lot_...
37
 * some sites mentions an RLE type compression also.
38
 */
39

    
40
#include "avformat.h"
41

    
42
/* bitstream minipacket size */
43
#define GIF_CHUNKS 100
44

    
45
/* slows down the decoding (and some browsers doesn't like it) */
46
/* #define GIF_ADD_APP_HEADER */
47

    
48
typedef struct {
49
    unsigned char r;
50
    unsigned char g;
51
    unsigned char b;
52
} rgb_triplet;
53

    
54
/* we use the standard 216 color palette */
55

    
56
/* this script was used to create the palette:
57
 * for r in 00 33 66 99 cc ff; do for g in 00 33 66 99 cc ff; do echo -n "    "; for b in 00 33 66 99 cc ff; do 
58
 *   echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
59
 */
60

    
61
static const rgb_triplet gif_clut[216] = {
62
    { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
63
    { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
64
    { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
65
    { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
66
    { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
67
    { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
68
    { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
69
    { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
70
    { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
71
    { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
72
    { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
73
    { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
74
    { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
75
    { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
76
    { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
77
    { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
78
    { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
79
    { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
80
    { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
81
    { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
82
    { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
83
    { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
84
    { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
85
    { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
86
    { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
87
    { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
88
    { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
89
    { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
90
    { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
91
    { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
92
    { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
93
    { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
94
    { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
95
    { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
96
    { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
97
    { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
98
};
99

    
100
/* The GIF format uses reversed order for bitstreams... */
101
/* at least they don't use PDP_ENDIAN :) */
102
/* so we 'extend' PutBitContext. hmmm, OOP :) */
103
/* seems this thing changed slightly since I wrote it... */
104

    
105
#ifdef ALT_BITSTREAM_WRITER
106
# error no ALT_BITSTREAM_WRITER support for now
107
#endif
108

    
109
static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
110
{
111
    unsigned int bit_buf;
112
    int bit_cnt;
113

    
114
#ifdef STATS
115
    st_out_bit_counts[st_current_index] += n;
116
#endif
117
    //    printf("put_bits=%d %x\n", n, value);
118
    assert(n == 32 || value < (1U << n));
119

    
120
    bit_buf = s->bit_buf;
121
    bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
122

    
123
    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
124
    /* XXX: optimize */
125
    if (n < (32-bit_cnt)) {
126
        bit_buf |= value << (bit_cnt);
127
        bit_cnt+=n;
128
    } else {
129
        bit_buf |= value << (bit_cnt);
130
        
131
        *s->buf_ptr = bit_buf & 0xff;
132
        s->buf_ptr[1] = (bit_buf >> 8) & 0xff;
133
        s->buf_ptr[2] = (bit_buf >> 16) & 0xff;
134
        s->buf_ptr[3] = (bit_buf >> 24) & 0xff;
135
        
136
        //printf("bitbuf = %08x\n", bit_buf);
137
        s->buf_ptr+=4;
138
        if (s->buf_ptr >= s->buf_end)
139
            puts("bit buffer overflow !!"); // should never happen ! who got rid of the callback ???
140
//            flush_buffer_rev(s);
141
        bit_cnt=bit_cnt + n - 32;
142
        if (bit_cnt == 0) {
143
            bit_buf = 0;
144
        } else {
145
            bit_buf = value >> (n - bit_cnt);
146
        }
147
    }
148

    
149
    s->bit_buf = bit_buf;
150
    s->bit_left = 32 - bit_cnt;
151
}
152

    
153
/* pad the end of the output stream with zeros */
154
static void gif_flush_put_bits_rev(PutBitContext *s)
155
{
156
    while (s->bit_left < 32) {
157
        /* XXX: should test end of buffer */
158
        *s->buf_ptr++=s->bit_buf & 0xff;
159
        s->bit_buf>>=8;
160
        s->bit_left+=8;
161
    }
162
//    flush_buffer_rev(s);
163
    s->bit_left=32;
164
    s->bit_buf=0;
165
}
166

    
167
/* !RevPutBitContext */
168

    
169
/* GIF header */
170
static int gif_image_write_header(ByteIOContext *pb, 
171
                                  int width, int height, uint32_t *palette)
172
{
173
    int i;
174
    unsigned int v;
175

    
176
    put_tag(pb, "GIF");
177
    put_tag(pb, "89a");
178
    put_le16(pb, width);
179
    put_le16(pb, height);
180

    
181
    put_byte(pb, 0xf7); /* flags: global clut, 256 entries */
182
    put_byte(pb, 0x1f); /* background color index */
183
    put_byte(pb, 0); /* aspect ratio */
184

    
185
    /* the global palette */
186
    if (!palette) {
187
        put_buffer(pb, (unsigned char *)gif_clut, 216*3);
188
        for(i=0;i<((256-216)*3);i++)
189
            put_byte(pb, 0);
190
    } else {
191
        for(i=0;i<256;i++) {
192
            v = palette[i];
193
            put_byte(pb, (v >> 16) & 0xff);
194
            put_byte(pb, (v >> 8) & 0xff);
195
            put_byte(pb, (v) & 0xff);
196
        }
197
    }
198

    
199
    /* application extension header */
200
    /* XXX: not really sure what to put in here... */
201
#ifdef GIF_ADD_APP_HEADER
202
    put_byte(pb, 0x21);
203
    put_byte(pb, 0xff);
204
    put_byte(pb, 0x0b);
205
    put_tag(pb, "NETSCAPE2.0");
206
    put_byte(pb, 0x03);
207
    put_byte(pb, 0x01);
208
    put_byte(pb, 0x00);
209
    put_byte(pb, 0x00);
210
#endif
211
    return 0;
212
}
213

    
214
/* this is maybe slow, but allows for extensions */
215
static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
216
{
217
    return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
218
}
219

    
220

    
221
static int gif_image_write_image(ByteIOContext *pb, 
222
                                 int x1, int y1, int width, int height,
223
                                 const uint8_t *buf, int linesize, int pix_fmt)
224
{
225
    PutBitContext p;
226
    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
227
    int i, left, w, v;
228
    const uint8_t *ptr;
229
    /* image block */
230

    
231
    put_byte(pb, 0x2c);
232
    put_le16(pb, x1);
233
    put_le16(pb, y1);
234
    put_le16(pb, width);
235
    put_le16(pb, height);
236
    put_byte(pb, 0x00); /* flags */
237
    /* no local clut */
238

    
239
    put_byte(pb, 0x08);
240

    
241
    left= width * height;
242

    
243
    init_put_bits(&p, buffer, 130);
244

    
245
/*
246
 * the thing here is the bitstream is written as little packets, with a size byte before
247
 * but it's still the same bitstream between packets (no flush !)
248
 */
249
    ptr = buf;
250
    w = width;
251
    while(left>0) {
252

    
253
        gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
254

    
255
        for(i=0;i<GIF_CHUNKS;i++) {
256
            if (pix_fmt == PIX_FMT_RGB24) {
257
                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
258
                ptr+=3;
259
            } else {
260
                v = *ptr++;
261
            }
262
            gif_put_bits_rev(&p, 9, v);
263
            if (--w == 0) {
264
                w = width;
265
                buf += linesize;
266
                ptr = buf;
267
            }
268
        }
269

    
270
        if(left<=GIF_CHUNKS) {
271
            gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
272
            gif_flush_put_bits_rev(&p);
273
        }
274
        if(pbBufPtr(&p) - p.buf > 0) {
275
            put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
276
            put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
277
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
278
        }
279
        if(left<=GIF_CHUNKS) {
280
            put_byte(pb, 0x00); /* end of image block */
281
        }
282

    
283
        left-=GIF_CHUNKS;
284
    }
285
    return 0;
286
}
287

    
288
typedef struct {
289
    int64_t time, file_time;
290
    uint8_t buffer[100]; /* data chunks */
291
} GIFContext;
292

    
293
static int gif_write_header(AVFormatContext *s)
294
{
295
    GIFContext *gif = s->priv_data;
296
    ByteIOContext *pb = &s->pb;
297
    AVCodecContext *enc, *video_enc;
298
    int i, width, height/*, rate*/;
299

    
300
/* XXX: do we reject audio streams or just ignore them ?
301
    if(s->nb_streams > 1)
302
        return -1;
303
*/
304
    gif->time = 0;
305
    gif->file_time = 0;
306

    
307
    video_enc = NULL;
308
    for(i=0;i<s->nb_streams;i++) {
309
        enc = &s->streams[i]->codec;
310
        if (enc->codec_type != CODEC_TYPE_AUDIO)
311
            video_enc = enc;
312
    }
313

    
314
    if (!video_enc) {
315
        av_free(gif);
316
        return -1;
317
    } else {
318
        width = video_enc->width;
319
        height = video_enc->height;
320
//        rate = video_enc->frame_rate;
321
    }
322

    
323
    /* XXX: is it allowed ? seems to work so far... */
324
    video_enc->pix_fmt = PIX_FMT_RGB24;
325

    
326
    gif_image_write_header(pb, width, height, NULL);
327

    
328
    put_flush_packet(&s->pb);
329
    return 0;
330
}
331

    
332
static int gif_write_video(AVFormatContext *s, 
333
                           AVCodecContext *enc, const uint8_t *buf, int size)
334
{
335
    ByteIOContext *pb = &s->pb;
336
    GIFContext *gif = s->priv_data;
337
    int jiffies;
338
    int64_t delay;
339

    
340
    /* graphic control extension block */
341
    put_byte(pb, 0x21);
342
    put_byte(pb, 0xf9);
343
    put_byte(pb, 0x04); /* block size */
344
    put_byte(pb, 0x04); /* flags */
345
    
346
    /* 1 jiffy is 1/70 s */
347
    /* the delay_time field indicates the number of jiffies - 1 */
348
    delay = gif->file_time - gif->time;
349

    
350
    /* XXX: should use delay, in order to be more accurate */
351
    /* instead of using the same rounded value each time */
352
    /* XXX: don't even remember if I really use it for now */
353
    jiffies = (70*enc->frame_rate_base/enc->frame_rate) - 1;
354

    
355
    put_le16(pb, jiffies);
356

    
357
    put_byte(pb, 0x1f); /* transparent color index */
358
    put_byte(pb, 0x00);
359

    
360
    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
361
                          buf, enc->width * 3, PIX_FMT_RGB24);
362

    
363
    put_flush_packet(&s->pb);
364
    return 0;
365
}
366

    
367
static int gif_write_packet(AVFormatContext *s, int stream_index, 
368
                            const uint8_t *buf, int size, int64_t pts)
369
{
370
    AVCodecContext *codec = &s->streams[stream_index]->codec;
371
    if (codec->codec_type == CODEC_TYPE_AUDIO)
372
        return 0; /* just ignore audio */
373
    else
374
        return gif_write_video(s, codec, buf, size);
375
}
376

    
377
static int gif_write_trailer(AVFormatContext *s)
378
{
379
    ByteIOContext *pb = &s->pb;
380

    
381
    put_byte(pb, 0x3b);
382
    put_flush_packet(&s->pb);
383
    return 0;
384
}
385

    
386
/* better than nothing gif image writer */
387
int gif_write(ByteIOContext *pb, AVImageInfo *info)
388
{
389
    gif_image_write_header(pb, info->width, info->height, 
390
                           (uint32_t *)info->pict.data[1]);
391
    gif_image_write_image(pb, 0, 0, info->width, info->height, 
392
                          info->pict.data[0], info->pict.linesize[0], 
393
                          PIX_FMT_PAL8);
394
    put_byte(pb, 0x3b);
395
    put_flush_packet(pb);
396
    return 0;
397
}
398

    
399
static AVOutputFormat gif_oformat = {
400
    "gif",
401
    "GIF Animation",
402
    "image/gif",
403
    "gif",
404
    sizeof(GIFContext),
405
    CODEC_ID_NONE,
406
    CODEC_ID_RAWVIDEO,
407
    gif_write_header,
408
    gif_write_packet,
409
    gif_write_trailer,
410
};
411

    
412
extern AVInputFormat gif_iformat;
413

    
414
int gif_init(void)
415
{
416
    av_register_output_format(&gif_oformat);
417
    av_register_input_format(&gif_iformat);
418
    return 0;
419
}