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1
/*
2
 * Animated GIF encoder
3
 * Copyright (c) 2000 Fabrice Bellard.
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 *
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 * This library 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 of the License, or (at your option) any later version.
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 *
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 * This library 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 this library; 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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 */
19

    
20
/*
21
 * 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.
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 */
39

    
40
#include "avformat.h"
41
#include "bitstream.h"
42

    
43
/* bitstream minipacket size */
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#define GIF_CHUNKS 100
45

    
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/* 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
49

    
50
typedef struct {
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    unsigned char r;
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    unsigned char g;
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    unsigned char b;
54
} rgb_triplet;
55

    
56
/* we use the standard 216 color palette */
57

    
58
/* 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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 */
62

    
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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 },
65
    { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
66
    { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
67
    { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
68
    { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
69
    { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
70
    { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
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    { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
72
    { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
73
    { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
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    { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
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    { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
76
    { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
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    { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
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    { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
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    { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
80
    { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
81
    { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
82
    { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
83
    { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
84
    { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
85
    { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
86
    { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
87
    { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
88
    { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
89
    { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
90
    { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
91
    { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
92
    { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
93
    { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
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    { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
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    { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
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    { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
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    { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
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    { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
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    { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
100
};
101

    
102
/* The GIF format uses reversed order for bitstreams... */
103
/* at least they don't use PDP_ENDIAN :) */
104
/* so we 'extend' PutBitContext. hmmm, OOP :) */
105
/* seems this thing changed slightly since I wrote it... */
106

    
107
#ifdef ALT_BITSTREAM_WRITER
108
# error no ALT_BITSTREAM_WRITER support for now
109
#endif
110

    
111
static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
112
{
113
    unsigned int bit_buf;
114
    int bit_cnt;
115

    
116
    //    printf("put_bits=%d %x\n", n, value);
117
    assert(n == 32 || value < (1U << n));
118

    
119
    bit_buf = s->bit_buf;
120
    bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
121

    
122
    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
123
    /* XXX: optimize */
124
    if (n < (32-bit_cnt)) {
125
        bit_buf |= value << (bit_cnt);
126
        bit_cnt+=n;
127
    } else {
128
        bit_buf |= value << (bit_cnt);
129

    
130
        *s->buf_ptr = bit_buf & 0xff;
131
        s->buf_ptr[1] = (bit_buf >> 8) & 0xff;
132
        s->buf_ptr[2] = (bit_buf >> 16) & 0xff;
133
        s->buf_ptr[3] = (bit_buf >> 24) & 0xff;
134

    
135
        //printf("bitbuf = %08x\n", bit_buf);
136
        s->buf_ptr+=4;
137
        if (s->buf_ptr >= s->buf_end)
138
            puts("bit buffer overflow !!"); // should never happen ! who got rid of the callback ???
139
//            flush_buffer_rev(s);
140
        bit_cnt=bit_cnt + n - 32;
141
        if (bit_cnt == 0) {
142
            bit_buf = 0;
143
        } else {
144
            bit_buf = value >> (n - bit_cnt);
145
        }
146
    }
147

    
148
    s->bit_buf = bit_buf;
149
    s->bit_left = 32 - bit_cnt;
150
}
151

    
152
/* pad the end of the output stream with zeros */
153
static void gif_flush_put_bits_rev(PutBitContext *s)
154
{
155
    while (s->bit_left < 32) {
156
        /* XXX: should test end of buffer */
157
        *s->buf_ptr++=s->bit_buf & 0xff;
158
        s->bit_buf>>=8;
159
        s->bit_left+=8;
160
    }
161
//    flush_buffer_rev(s);
162
    s->bit_left=32;
163
    s->bit_buf=0;
164
}
165

    
166
/* !RevPutBitContext */
167

    
168
/* GIF header */
169
static int gif_image_write_header(ByteIOContext *pb,
170
                                  int width, int height, int loop_count,
171
                                  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 */
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    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, (const 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
        /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
200
                see http://members.aol.com/royalef/gifabout.htm#net-extension
201

202
                byte   1       : 33 (hex 0x21) GIF Extension code
203
                byte   2       : 255 (hex 0xFF) Application Extension Label
204
                byte   3       : 11 (hex (0x0B) Length of Application Block
205
                                         (eleven bytes of data to follow)
206
                bytes  4 to 11 : "NETSCAPE"
207
                bytes 12 to 14 : "2.0"
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                byte  15       : 3 (hex 0x03) Length of Data Sub-Block
209
                                         (three bytes of data to follow)
210
                byte  16       : 1 (hex 0x01)
211
                bytes 17 to 18 : 0 to 65535, an unsigned integer in
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                                         lo-hi byte format. This indicate the
213
                                         number of iterations the loop should
214
                                         be executed.
215
                bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
216
        */
217

    
218
    /* application extension header */
219
#ifdef GIF_ADD_APP_HEADER
220
    if (loop_count >= 0 && loop_count <= 65535) {
221
    put_byte(pb, 0x21);
222
    put_byte(pb, 0xff);
223
    put_byte(pb, 0x0b);
224
        put_tag(pb, "NETSCAPE2.0");  // bytes 4 to 14
225
        put_byte(pb, 0x03); // byte 15
226
        put_byte(pb, 0x01); // byte 16
227
        put_le16(pb, (uint16_t)loop_count);
228
        put_byte(pb, 0x00); // byte 19
229
    }
230
#endif
231
    return 0;
232
}
233

    
234
/* this is maybe slow, but allows for extensions */
235
static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
236
{
237
    return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
238
}
239

    
240

    
241
static int gif_image_write_image(ByteIOContext *pb,
242
                                 int x1, int y1, int width, int height,
243
                                 const uint8_t *buf, int linesize, int pix_fmt)
244
{
245
    PutBitContext p;
246
    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
247
    int i, left, w, v;
248
    const uint8_t *ptr;
249
    /* image block */
250

    
251
    put_byte(pb, 0x2c);
252
    put_le16(pb, x1);
253
    put_le16(pb, y1);
254
    put_le16(pb, width);
255
    put_le16(pb, height);
256
    put_byte(pb, 0x00); /* flags */
257
    /* no local clut */
258

    
259
    put_byte(pb, 0x08);
260

    
261
    left= width * height;
262

    
263
    init_put_bits(&p, buffer, 130);
264

    
265
/*
266
 * the thing here is the bitstream is written as little packets, with a size byte before
267
 * but it's still the same bitstream between packets (no flush !)
268
 */
269
    ptr = buf;
270
    w = width;
271
    while(left>0) {
272

    
273
        gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
274

    
275
        for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
276
            if (pix_fmt == PIX_FMT_RGB24) {
277
                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
278
                ptr+=3;
279
            } else {
280
                v = *ptr++;
281
            }
282
            gif_put_bits_rev(&p, 9, v);
283
            if (--w == 0) {
284
                w = width;
285
                buf += linesize;
286
                ptr = buf;
287
            }
288
        }
289

    
290
        if(left<=GIF_CHUNKS) {
291
            gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
292
            gif_flush_put_bits_rev(&p);
293
        }
294
        if(pbBufPtr(&p) - p.buf > 0) {
295
            put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
296
            put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
297
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
298
        }
299
        left-=GIF_CHUNKS;
300
    }
301
    put_byte(pb, 0x00); /* end of image block */
302

    
303
    return 0;
304
}
305

    
306
typedef struct {
307
    int64_t time, file_time;
308
    uint8_t buffer[100]; /* data chunks */
309
} GIFContext;
310

    
311
static int gif_write_header(AVFormatContext *s)
312
{
313
    GIFContext *gif = s->priv_data;
314
    ByteIOContext *pb = &s->pb;
315
    AVCodecContext *enc, *video_enc;
316
    int i, width, height, loop_count /*, rate*/;
317

    
318
/* XXX: do we reject audio streams or just ignore them ?
319
    if(s->nb_streams > 1)
320
        return -1;
321
*/
322
    gif->time = 0;
323
    gif->file_time = 0;
324

    
325
    video_enc = NULL;
326
    for(i=0;i<s->nb_streams;i++) {
327
        enc = s->streams[i]->codec;
328
        if (enc->codec_type != CODEC_TYPE_AUDIO)
329
            video_enc = enc;
330
    }
331

    
332
    if (!video_enc) {
333
        av_free(gif);
334
        return -1;
335
    } else {
336
        width = video_enc->width;
337
        height = video_enc->height;
338
        loop_count = s->loop_output;
339
//        rate = video_enc->time_base.den;
340
    }
341

    
342
    /* XXX: is it allowed ? seems to work so far... */
343
    video_enc->pix_fmt = PIX_FMT_RGB24;
344

    
345
    gif_image_write_header(pb, width, height, loop_count, NULL);
346

    
347
    put_flush_packet(&s->pb);
348
    return 0;
349
}
350

    
351
static int gif_write_video(AVFormatContext *s,
352
                           AVCodecContext *enc, const uint8_t *buf, int size)
353
{
354
    ByteIOContext *pb = &s->pb;
355
    GIFContext *gif = s->priv_data;
356
    int jiffies;
357
    int64_t delay;
358

    
359
    /* graphic control extension block */
360
    put_byte(pb, 0x21);
361
    put_byte(pb, 0xf9);
362
    put_byte(pb, 0x04); /* block size */
363
    put_byte(pb, 0x04); /* flags */
364

    
365
    /* 1 jiffy is 1/70 s */
366
    /* the delay_time field indicates the number of jiffies - 1 */
367
    delay = gif->file_time - gif->time;
368

    
369
    /* XXX: should use delay, in order to be more accurate */
370
    /* instead of using the same rounded value each time */
371
    /* XXX: don't even remember if I really use it for now */
372
    jiffies = (70*enc->time_base.num/enc->time_base.den) - 1;
373

    
374
    put_le16(pb, jiffies);
375

    
376
    put_byte(pb, 0x1f); /* transparent color index */
377
    put_byte(pb, 0x00);
378

    
379
    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
380
                          buf, enc->width * 3, PIX_FMT_RGB24);
381

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

    
386
static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
387
{
388
    AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
389
    if (codec->codec_type == CODEC_TYPE_AUDIO)
390
        return 0; /* just ignore audio */
391
    else
392
        return gif_write_video(s, codec, pkt->data, pkt->size);
393
}
394

    
395
static int gif_write_trailer(AVFormatContext *s)
396
{
397
    ByteIOContext *pb = &s->pb;
398

    
399
    put_byte(pb, 0x3b);
400
    put_flush_packet(&s->pb);
401
    return 0;
402
}
403

    
404
/* better than nothing gif image writer */
405
int gif_write(ByteIOContext *pb, AVImageInfo *info)
406
{
407
    gif_image_write_header(pb, info->width, info->height, AVFMT_NOOUTPUTLOOP,
408
                           (uint32_t *)info->pict.data[1]);
409
    gif_image_write_image(pb, 0, 0, info->width, info->height,
410
                          info->pict.data[0], info->pict.linesize[0],
411
                          PIX_FMT_PAL8);
412
    put_byte(pb, 0x3b);
413
    put_flush_packet(pb);
414
    return 0;
415
}
416

    
417
static AVOutputFormat gif_oformat = {
418
    "gif",
419
    "GIF Animation",
420
    "image/gif",
421
    "gif",
422
    sizeof(GIFContext),
423
    CODEC_ID_NONE,
424
    CODEC_ID_RAWVIDEO,
425
    gif_write_header,
426
    gif_write_packet,
427
    gif_write_trailer,
428
};
429

    
430
extern AVInputFormat gif_iformat;
431

    
432
int gif_init(void)
433
{
434
    av_register_output_format(&gif_oformat);
435
    av_register_input_format(&gif_iformat);
436
    return 0;
437
}