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ffmpeg / libavformat / gif.c @ b316aa1a

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1
/*
2
 * Animated GIF muxer
3
 * Copyright (c) 2000 Fabrice Bellard.
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
21

    
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/*
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 * First version by Francois Revol revol@free.fr
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 *
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 * Features and limitations:
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 * - currently no compression is performed,
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 *   in fact the size of the data is 9/8 the size of the image in 8bpp
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 * - uses only a global standard palette
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 * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
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 *
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 * Reference documents:
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 * http://www.goice.co.jp/member/mo/formats/gif.html
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 * http://astronomy.swin.edu.au/pbourke/dataformats/gif/
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 * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
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 *
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 * this url claims to have an LZW algorithm not covered by Unisys patent:
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 * http://www.msg.net/utility/whirlgif/gifencod.html
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 * could help reduce the size of the files _a lot_...
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 * some sites mentions an RLE type compression also.
40
 */
41

    
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#include "avformat.h"
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#include "bitstream.h"
44

    
45
/* bitstream minipacket size */
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#define GIF_CHUNKS 100
47

    
48
/* slows down the decoding (and some browsers don't like it) */
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/* 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 */
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#define GIF_ADD_APP_HEADER // required to enable looping of animated gif
51

    
52
typedef struct {
53
    unsigned char r;
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    unsigned char g;
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    unsigned char b;
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} rgb_triplet;
57

    
58
/* we use the standard 216 color palette */
59

    
60
/* this script was used to create the palette:
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 * 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
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 *   echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
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 */
64

    
65
static const rgb_triplet gif_clut[216] = {
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    { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
67
    { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
68
    { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
69
    { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
70
    { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
71
    { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
72
    { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
73
    { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
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    { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
75
    { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
76
    { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
77
    { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
78
    { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
79
    { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
80
    { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
81
    { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
82
    { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
83
    { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
84
    { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
85
    { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
86
    { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
87
    { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
88
    { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
89
    { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
90
    { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
91
    { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
92
    { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
93
    { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
94
    { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
95
    { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
96
    { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
97
    { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
98
    { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
99
    { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
100
    { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
101
    { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
102
};
103

    
104
/* The GIF format uses reversed order for bitstreams... */
105
/* at least they don't use PDP_ENDIAN :) */
106
/* so we 'extend' PutBitContext. hmmm, OOP :) */
107
/* seems this thing changed slightly since I wrote it... */
108

    
109
#ifdef ALT_BITSTREAM_WRITER
110
# error no ALT_BITSTREAM_WRITER support for now
111
#endif
112

    
113
static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
114
{
115
    unsigned int bit_buf;
116
    int bit_cnt;
117

    
118
    //    printf("put_bits=%d %x\n", n, value);
119
    assert(n == 32 || value < (1U << n));
120

    
121
    bit_buf = s->bit_buf;
122
    bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
123

    
124
    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
125
    /* XXX: optimize */
126
    if (n < (32-bit_cnt)) {
127
        bit_buf |= value << (bit_cnt);
128
        bit_cnt+=n;
129
    } else {
130
        bit_buf |= value << (bit_cnt);
131

    
132
        *s->buf_ptr = bit_buf & 0xff;
133
        s->buf_ptr[1] = (bit_buf >> 8) & 0xff;
134
        s->buf_ptr[2] = (bit_buf >> 16) & 0xff;
135
        s->buf_ptr[3] = (bit_buf >> 24) & 0xff;
136

    
137
        //printf("bitbuf = %08x\n", bit_buf);
138
        s->buf_ptr+=4;
139
        if (s->buf_ptr >= s->buf_end)
140
            puts("bit buffer overflow !!"); // should never happen ! who got rid of the callback ???
141
//            flush_buffer_rev(s);
142
        bit_cnt=bit_cnt + n - 32;
143
        if (bit_cnt == 0) {
144
            bit_buf = 0;
145
        } else {
146
            bit_buf = value >> (n - bit_cnt);
147
        }
148
    }
149

    
150
    s->bit_buf = bit_buf;
151
    s->bit_left = 32 - bit_cnt;
152
}
153

    
154
/* pad the end of the output stream with zeros */
155
static void gif_flush_put_bits_rev(PutBitContext *s)
156
{
157
    while (s->bit_left < 32) {
158
        /* XXX: should test end of buffer */
159
        *s->buf_ptr++=s->bit_buf & 0xff;
160
        s->bit_buf>>=8;
161
        s->bit_left+=8;
162
    }
163
//    flush_buffer_rev(s);
164
    s->bit_left=32;
165
    s->bit_buf=0;
166
}
167

    
168
/* !RevPutBitContext */
169

    
170
/* GIF header */
171
static int gif_image_write_header(ByteIOContext *pb,
172
                                  int width, int height, int loop_count,
173
                                  uint32_t *palette)
174
{
175
    int i;
176
    unsigned int v;
177

    
178
    put_tag(pb, "GIF");
179
    put_tag(pb, "89a");
180
    put_le16(pb, width);
181
    put_le16(pb, height);
182

    
183
    put_byte(pb, 0xf7); /* flags: global clut, 256 entries */
184
    put_byte(pb, 0x1f); /* background color index */
185
    put_byte(pb, 0); /* aspect ratio */
186

    
187
    /* the global palette */
188
    if (!palette) {
189
        put_buffer(pb, (const unsigned char *)gif_clut, 216*3);
190
        for(i=0;i<((256-216)*3);i++)
191
            put_byte(pb, 0);
192
    } else {
193
        for(i=0;i<256;i++) {
194
            v = palette[i];
195
            put_byte(pb, (v >> 16) & 0xff);
196
            put_byte(pb, (v >> 8) & 0xff);
197
            put_byte(pb, (v) & 0xff);
198
        }
199
    }
200

    
201
        /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
202
                see http://members.aol.com/royalef/gifabout.htm#net-extension
203

204
                byte   1       : 33 (hex 0x21) GIF Extension code
205
                byte   2       : 255 (hex 0xFF) Application Extension Label
206
                byte   3       : 11 (hex (0x0B) Length of Application Block
207
                                         (eleven bytes of data to follow)
208
                bytes  4 to 11 : "NETSCAPE"
209
                bytes 12 to 14 : "2.0"
210
                byte  15       : 3 (hex 0x03) Length of Data Sub-Block
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                                         (three bytes of data to follow)
212
                byte  16       : 1 (hex 0x01)
213
                bytes 17 to 18 : 0 to 65535, an unsigned integer in
214
                                         lo-hi byte format. This indicate the
215
                                         number of iterations the loop should
216
                                         be executed.
217
                bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
218
        */
219

    
220
    /* application extension header */
221
#ifdef GIF_ADD_APP_HEADER
222
    if (loop_count >= 0 && loop_count <= 65535) {
223
    put_byte(pb, 0x21);
224
    put_byte(pb, 0xff);
225
    put_byte(pb, 0x0b);
226
        put_tag(pb, "NETSCAPE2.0");  // bytes 4 to 14
227
        put_byte(pb, 0x03); // byte 15
228
        put_byte(pb, 0x01); // byte 16
229
        put_le16(pb, (uint16_t)loop_count);
230
        put_byte(pb, 0x00); // byte 19
231
    }
232
#endif
233
    return 0;
234
}
235

    
236
/* this is maybe slow, but allows for extensions */
237
static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
238
{
239
    return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
240
}
241

    
242

    
243
static int gif_image_write_image(ByteIOContext *pb,
244
                                 int x1, int y1, int width, int height,
245
                                 const uint8_t *buf, int linesize, int pix_fmt)
246
{
247
    PutBitContext p;
248
    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
249
    int i, left, w, v;
250
    const uint8_t *ptr;
251
    /* image block */
252

    
253
    put_byte(pb, 0x2c);
254
    put_le16(pb, x1);
255
    put_le16(pb, y1);
256
    put_le16(pb, width);
257
    put_le16(pb, height);
258
    put_byte(pb, 0x00); /* flags */
259
    /* no local clut */
260

    
261
    put_byte(pb, 0x08);
262

    
263
    left= width * height;
264

    
265
    init_put_bits(&p, buffer, 130);
266

    
267
/*
268
 * the thing here is the bitstream is written as little packets, with a size byte before
269
 * but it's still the same bitstream between packets (no flush !)
270
 */
271
    ptr = buf;
272
    w = width;
273
    while(left>0) {
274

    
275
        gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
276

    
277
        for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
278
            if (pix_fmt == PIX_FMT_RGB24) {
279
                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
280
                ptr+=3;
281
            } else {
282
                v = *ptr++;
283
            }
284
            gif_put_bits_rev(&p, 9, v);
285
            if (--w == 0) {
286
                w = width;
287
                buf += linesize;
288
                ptr = buf;
289
            }
290
        }
291

    
292
        if(left<=GIF_CHUNKS) {
293
            gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
294
            gif_flush_put_bits_rev(&p);
295
        }
296
        if(pbBufPtr(&p) - p.buf > 0) {
297
            put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
298
            put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
299
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
300
        }
301
        left-=GIF_CHUNKS;
302
    }
303
    put_byte(pb, 0x00); /* end of image block */
304

    
305
    return 0;
306
}
307

    
308
typedef struct {
309
    int64_t time, file_time;
310
    uint8_t buffer[100]; /* data chunks */
311
} GIFContext;
312

    
313
static int gif_write_header(AVFormatContext *s)
314
{
315
    GIFContext *gif = s->priv_data;
316
    ByteIOContext *pb = &s->pb;
317
    AVCodecContext *enc, *video_enc;
318
    int i, width, height, loop_count /*, rate*/;
319

    
320
/* XXX: do we reject audio streams or just ignore them ?
321
    if(s->nb_streams > 1)
322
        return -1;
323
*/
324
    gif->time = 0;
325
    gif->file_time = 0;
326

    
327
    video_enc = NULL;
328
    for(i=0;i<s->nb_streams;i++) {
329
        enc = s->streams[i]->codec;
330
        if (enc->codec_type != CODEC_TYPE_AUDIO)
331
            video_enc = enc;
332
    }
333

    
334
    if (!video_enc) {
335
        av_free(gif);
336
        return -1;
337
    } else {
338
        width = video_enc->width;
339
        height = video_enc->height;
340
        loop_count = s->loop_output;
341
//        rate = video_enc->time_base.den;
342
    }
343

    
344
    if (video_enc->pix_fmt != PIX_FMT_RGB24) {
345
        av_log(s, AV_LOG_ERROR, "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");
346
        return AVERROR(EIO);
347
    }
348

    
349
    gif_image_write_header(pb, width, height, loop_count, NULL);
350

    
351
    put_flush_packet(&s->pb);
352
    return 0;
353
}
354

    
355
static int gif_write_video(AVFormatContext *s,
356
                           AVCodecContext *enc, const uint8_t *buf, int size)
357
{
358
    ByteIOContext *pb = &s->pb;
359
    GIFContext *gif = s->priv_data;
360
    int jiffies;
361
    int64_t delay;
362

    
363
    /* graphic control extension block */
364
    put_byte(pb, 0x21);
365
    put_byte(pb, 0xf9);
366
    put_byte(pb, 0x04); /* block size */
367
    put_byte(pb, 0x04); /* flags */
368

    
369
    /* 1 jiffy is 1/70 s */
370
    /* the delay_time field indicates the number of jiffies - 1 */
371
    delay = gif->file_time - gif->time;
372

    
373
    /* XXX: should use delay, in order to be more accurate */
374
    /* instead of using the same rounded value each time */
375
    /* XXX: don't even remember if I really use it for now */
376
    jiffies = (70*enc->time_base.num/enc->time_base.den) - 1;
377

    
378
    put_le16(pb, jiffies);
379

    
380
    put_byte(pb, 0x1f); /* transparent color index */
381
    put_byte(pb, 0x00);
382

    
383
    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
384
                          buf, enc->width * 3, PIX_FMT_RGB24);
385

    
386
    put_flush_packet(&s->pb);
387
    return 0;
388
}
389

    
390
static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
391
{
392
    AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
393
    if (codec->codec_type == CODEC_TYPE_AUDIO)
394
        return 0; /* just ignore audio */
395
    else
396
        return gif_write_video(s, codec, pkt->data, pkt->size);
397
}
398

    
399
static int gif_write_trailer(AVFormatContext *s)
400
{
401
    ByteIOContext *pb = &s->pb;
402

    
403
    put_byte(pb, 0x3b);
404
    put_flush_packet(&s->pb);
405
    return 0;
406
}
407

    
408
AVOutputFormat gif_muxer = {
409
    "gif",
410
    "GIF Animation",
411
    "image/gif",
412
    "gif",
413
    sizeof(GIFContext),
414
    CODEC_ID_NONE,
415
    CODEC_ID_RAWVIDEO,
416
    gif_write_header,
417
    gif_write_packet,
418
    gif_write_trailer,
419
};