aboutsummaryrefslogtreecommitdiffstats
path: root/libavformat/gif.c
blob: eb2db46b3ea69c4439fb2bd80161d85e1d280b7a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
/*
 * Animated GIF muxer
 * Copyright (c) 2000 Fabrice Bellard
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

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

#include "avformat.h"
#include "libavutil/log.h"
#include "libavutil/opt.h"

/* The GIF format uses reversed order for bitstreams... */
/* at least they don't use PDP_ENDIAN :) */
#define BITSTREAM_WRITER_LE

#include "libavcodec/put_bits.h"

/* bitstream minipacket size */
#define GIF_CHUNKS 100

/* slows down the decoding (and some browsers don't like it) */
/* update on the 'some browsers don't like it issue from above:
 * this was probably due to missing 'Data Sub-block Terminator'
 * (byte 19) in the app_header */
#define GIF_ADD_APP_HEADER // required to enable looping of animated gif

typedef struct {
    unsigned char r;
    unsigned char g;
    unsigned char b;
} rgb_triplet;

/* we use the standard 216 color palette */

/* this script was used to create the palette:
 * 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
 *             echo -n "{ 0x$r, 0x$g, 0x$b }, "
 *         done
 *         echo ""
 *     done
 * done
 */

static const rgb_triplet gif_clut[216] = {
    { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
    { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
    { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
    { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
    { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
    { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
    { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
    { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
    { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
    { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
    { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
    { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
    { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
    { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
    { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
    { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
    { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
    { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
    { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
    { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
    { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
    { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
    { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
    { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
    { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
    { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
    { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
    { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
    { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
    { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
    { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
    { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
    { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
    { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
    { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
    { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
};

/* GIF header */
static int gif_image_write_header(AVIOContext *pb, int width, int height,
                                  int loop_count, uint32_t *palette)
{
    int i;
    unsigned int v;

    avio_write(pb, "GIF", 3);
    avio_write(pb, "89a", 3);
    avio_wl16(pb, width);
    avio_wl16(pb, height);

    avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
    avio_w8(pb, 0x1f); /* background color index */
    avio_w8(pb, 0);    /* aspect ratio */

    /* the global palette */
    if (!palette) {
        avio_write(pb, (const unsigned char *)gif_clut, 216 * 3);
        for (i = 0; i < ((256 - 216) * 3); i++)
            avio_w8(pb, 0);
    } else {
        for (i = 0; i < 256; i++) {
            v = palette[i];
            avio_w8(pb, (v >> 16) & 0xff);
            avio_w8(pb, (v >>  8) & 0xff);
            avio_w8(pb, (v)       & 0xff);
        }
    }

    /* update: this is the 'NETSCAPE EXTENSION' that allows for looped animated
     * GIF, see http://members.aol.com/royalef/gifabout.htm#net-extension
     *
     * byte   1       : 33 (hex 0x21) GIF Extension code
     * byte   2       : 255 (hex 0xFF) Application Extension Label
     * byte   3       : 11 (hex (0x0B) Length of Application Block
     *                          (eleven bytes of data to follow)
     * bytes  4 to 11 : "NETSCAPE"
     * bytes 12 to 14 : "2.0"
     * byte  15       : 3 (hex 0x03) Length of Data Sub-Block
     *                          (three bytes of data to follow)
     * byte  16       : 1 (hex 0x01)
     * bytes 17 to 18 : 0 to 65535, an unsigned integer in
     *                          lo-hi byte format. This indicate the
     *                          number of iterations the loop should
     *                          be executed.
     * bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
     */

    /* application extension header */
#ifdef GIF_ADD_APP_HEADER
    if (loop_count >= 0 && loop_count <= 65535) {
        avio_w8(pb, 0x21);
        avio_w8(pb, 0xff);
        avio_w8(pb, 0x0b);
        // bytes 4 to 14
        avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);
        avio_w8(pb, 0x03); // byte 15
        avio_w8(pb, 0x01); // byte 16
        avio_wl16(pb, (uint16_t)loop_count);
        avio_w8(pb, 0x00); // byte 19
    }
#endif
    return 0;
}

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

static int gif_image_write_image(AVIOContext *pb,
                                 int x1, int y1, int width, int height,
                                 const uint8_t *buf, int linesize, int pix_fmt)
{
    PutBitContext p;
    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
    int i, left, w, v;
    const uint8_t *ptr;
    /* image block */

    avio_w8(pb, 0x2c);
    avio_wl16(pb, x1);
    avio_wl16(pb, y1);
    avio_wl16(pb, width);
    avio_wl16(pb, height);
    avio_w8(pb, 0x00); /* flags */
    /* no local clut */

    avio_w8(pb, 0x08);

    left = width * height;

    init_put_bits(&p, buffer, 130);

/*
 * the thing here is the bitstream is written as little packets, with a size
 * byte before but it's still the same bitstream between packets (no flush !)
 */
    ptr = buf;
    w   = width;
    while (left > 0) {
        put_bits(&p, 9, 0x0100); /* clear code */

        for (i = (left < GIF_CHUNKS) ? left : GIF_CHUNKS; i; i--) {
            if (pix_fmt == AV_PIX_FMT_RGB24) {
                v    = gif_clut_index(ptr[0], ptr[1], ptr[2]);
                ptr += 3;
            } else {
                v = *ptr++;
            }
            put_bits(&p, 9, v);
            if (--w == 0) {
                w    = width;
                buf += linesize;
                ptr  = buf;
            }
        }

        if (left <= GIF_CHUNKS) {
            put_bits(&p, 9, 0x101); /* end of stream */
            flush_put_bits(&p);
        }
        if (put_bits_ptr(&p) - p.buf > 0) {
            avio_w8(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
            avio_write(pb, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
        }
        left -= GIF_CHUNKS;
    }
    avio_w8(pb, 0x00); /* end of image block */

    return 0;
}

typedef struct {
    AVClass *class;         /** Class for private options. */
    int64_t time, file_time;
    uint8_t buffer[100]; /* data chunks */
    int loop;
} GIFContext;

static int gif_write_header(AVFormatContext *s)
{
    GIFContext *gif = s->priv_data;
    AVIOContext *pb = s->pb;
    AVCodecContext *enc, *video_enc;
    int i, width, height /*, rate*/;

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

    video_enc = NULL;
    for (i = 0; i < s->nb_streams; i++) {
        enc = s->streams[i]->codec;
        if (enc->codec_type != AVMEDIA_TYPE_AUDIO)
            video_enc = enc;
    }

    if (!video_enc) {
        av_free(gif);
        return -1;
    } else {
        width  = video_enc->width;
        height = video_enc->height;
//        rate = video_enc->time_base.den;
    }

    if (video_enc->pix_fmt != AV_PIX_FMT_RGB24) {
        av_log(s, AV_LOG_ERROR,
               "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");
        return AVERROR(EIO);
    }

    gif_image_write_header(pb, width, height, gif->loop, NULL);

    avio_flush(s->pb);
    return 0;
}

static int gif_write_video(AVFormatContext *s, AVCodecContext *enc,
                           const uint8_t *buf, int size)
{
    AVIOContext *pb = s->pb;
    int jiffies;

    /* graphic control extension block */
    avio_w8(pb, 0x21);
    avio_w8(pb, 0xf9);
    avio_w8(pb, 0x04); /* block size */
    avio_w8(pb, 0x04); /* flags */

    /* 1 jiffy is 1/70 s */
    /* the delay_time field indicates the number of jiffies - 1 */
    /* XXX: should use delay, in order to be more accurate */
    /* instead of using the same rounded value each time */
    /* XXX: don't even remember if I really use it for now */
    jiffies = (70 * enc->time_base.num / enc->time_base.den) - 1;

    avio_wl16(pb, jiffies);

    avio_w8(pb, 0x1f); /* transparent color index */
    avio_w8(pb, 0x00);

    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
                          buf, enc->width * 3, AV_PIX_FMT_RGB24);

    avio_flush(s->pb);
    return 0;
}

static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
    if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
        return 0; /* just ignore audio */
    else
        return gif_write_video(s, codec, pkt->data, pkt->size);
}

static int gif_write_trailer(AVFormatContext *s)
{
    AVIOContext *pb = s->pb;

    avio_w8(pb, 0x3b);

    return 0;
}

#define OFFSET(x) offsetof(GIFContext, x)
#define ENC AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
    { "loop", "Number of times to loop the output.", OFFSET(loop),
      AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 65535, ENC },
    { NULL },
};

static const AVClass gif_muxer_class = {
    .class_name = "GIF muxer",
    .item_name  = av_default_item_name,
    .version    = LIBAVUTIL_VERSION_INT,
    .option     = options,
};

AVOutputFormat ff_gif_muxer = {
    .name           = "gif",
    .long_name      = NULL_IF_CONFIG_SMALL("GIF Animation"),
    .mime_type      = "image/gif",
    .extensions     = "gif",
    .priv_data_size = sizeof(GIFContext),
    .audio_codec    = AV_CODEC_ID_NONE,
    .video_codec    = AV_CODEC_ID_RAWVIDEO,
    .write_header   = gif_write_header,
    .write_packet   = gif_write_packet,
    .write_trailer  = gif_write_trailer,
    .priv_class     = &gif_muxer_class,
};