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ffmpeg / libavformat / gif.c @ 5509bffa

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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
/*
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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.
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 */
39

    
40
#include "avformat.h"
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#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

    
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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

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

    
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/* 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 },
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    { 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 },
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    { 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 },
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    { 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 },
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    { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
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    { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
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    { 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
#ifdef STATS
117
    st_out_bit_counts[st_current_index] += n;
118
#endif
119
    //    printf("put_bits=%d %x\n", n, value);
120
    assert(n == 32 || value < (1U << n));
121

    
122
    bit_buf = s->bit_buf;
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    bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
124

    
125
    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
126
    /* XXX: optimize */
127
    if (n < (32-bit_cnt)) {
128
        bit_buf |= value << (bit_cnt);
129
        bit_cnt+=n;
130
    } else {
131
        bit_buf |= value << (bit_cnt);
132

    
133
        *s->buf_ptr = bit_buf & 0xff;
134
        s->buf_ptr[1] = (bit_buf >> 8) & 0xff;
135
        s->buf_ptr[2] = (bit_buf >> 16) & 0xff;
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        s->buf_ptr[3] = (bit_buf >> 24) & 0xff;
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138
        //printf("bitbuf = %08x\n", bit_buf);
139
        s->buf_ptr+=4;
140
        if (s->buf_ptr >= s->buf_end)
141
            puts("bit buffer overflow !!"); // should never happen ! who got rid of the callback ???
142
//            flush_buffer_rev(s);
143
        bit_cnt=bit_cnt + n - 32;
144
        if (bit_cnt == 0) {
145
            bit_buf = 0;
146
        } else {
147
            bit_buf = value >> (n - bit_cnt);
148
        }
149
    }
150

    
151
    s->bit_buf = bit_buf;
152
    s->bit_left = 32 - bit_cnt;
153
}
154

    
155
/* pad the end of the output stream with zeros */
156
static void gif_flush_put_bits_rev(PutBitContext *s)
157
{
158
    while (s->bit_left < 32) {
159
        /* XXX: should test end of buffer */
160
        *s->buf_ptr++=s->bit_buf & 0xff;
161
        s->bit_buf>>=8;
162
        s->bit_left+=8;
163
    }
164
//    flush_buffer_rev(s);
165
    s->bit_left=32;
166
    s->bit_buf=0;
167
}
168

    
169
/* !RevPutBitContext */
170

    
171
/* GIF header */
172
static int gif_image_write_header(ByteIOContext *pb,
173
                                  int width, int height, int loop_count,
174
                                  uint32_t *palette)
175
{
176
    int i;
177
    unsigned int v;
178

    
179
    put_tag(pb, "GIF");
180
    put_tag(pb, "89a");
181
    put_le16(pb, width);
182
    put_le16(pb, height);
183

    
184
    put_byte(pb, 0xf7); /* flags: global clut, 256 entries */
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    put_byte(pb, 0x1f); /* background color index */
186
    put_byte(pb, 0); /* aspect ratio */
187

    
188
    /* the global palette */
189
    if (!palette) {
190
        put_buffer(pb, (unsigned char *)gif_clut, 216*3);
191
        for(i=0;i<((256-216)*3);i++)
192
            put_byte(pb, 0);
193
    } else {
194
        for(i=0;i<256;i++) {
195
            v = palette[i];
196
            put_byte(pb, (v >> 16) & 0xff);
197
            put_byte(pb, (v >> 8) & 0xff);
198
            put_byte(pb, (v) & 0xff);
199
        }
200
    }
201

    
202
        /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
203
                see http://members.aol.com/royalef/gifabout.htm#net-extension
204

205
                byte   1       : 33 (hex 0x21) GIF Extension code
206
                byte   2       : 255 (hex 0xFF) Application Extension Label
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                byte   3       : 11 (hex (0x0B) Length of Application Block
208
                                         (eleven bytes of data to follow)
209
                bytes  4 to 11 : "NETSCAPE"
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                bytes 12 to 14 : "2.0"
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                byte  15       : 3 (hex 0x03) Length of Data Sub-Block
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                                         (three bytes of data to follow)
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                byte  16       : 1 (hex 0x01)
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                bytes 17 to 18 : 0 to 65535, an unsigned integer in
215
                                         lo-hi byte format. This indicate the
216
                                         number of iterations the loop should
217
                                         be executed.
218
                bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
219
        */
220

    
221
    /* application extension header */
222
#ifdef GIF_ADD_APP_HEADER
223
    if (loop_count >= 0 && loop_count <= 65535) {
224
    put_byte(pb, 0x21);
225
    put_byte(pb, 0xff);
226
    put_byte(pb, 0x0b);
227
        put_tag(pb, "NETSCAPE2.0");  // bytes 4 to 14
228
        put_byte(pb, 0x03); // byte 15
229
        put_byte(pb, 0x01); // byte 16
230
        put_le16(pb, (uint16_t)loop_count);
231
        put_byte(pb, 0x00); // byte 19
232
    }
233
#endif
234
    return 0;
235
}
236

    
237
/* this is maybe slow, but allows for extensions */
238
static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
239
{
240
    return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
241
}
242

    
243

    
244
static int gif_image_write_image(ByteIOContext *pb,
245
                                 int x1, int y1, int width, int height,
246
                                 const uint8_t *buf, int linesize, int pix_fmt)
247
{
248
    PutBitContext p;
249
    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
250
    int i, left, w, v;
251
    const uint8_t *ptr;
252
    /* image block */
253

    
254
    put_byte(pb, 0x2c);
255
    put_le16(pb, x1);
256
    put_le16(pb, y1);
257
    put_le16(pb, width);
258
    put_le16(pb, height);
259
    put_byte(pb, 0x00); /* flags */
260
    /* no local clut */
261

    
262
    put_byte(pb, 0x08);
263

    
264
    left= width * height;
265

    
266
    init_put_bits(&p, buffer, 130);
267

    
268
/*
269
 * the thing here is the bitstream is written as little packets, with a size byte before
270
 * but it's still the same bitstream between packets (no flush !)
271
 */
272
    ptr = buf;
273
    w = width;
274
    while(left>0) {
275

    
276
        gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
277

    
278
        for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
279
            if (pix_fmt == PIX_FMT_RGB24) {
280
                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
281
                ptr+=3;
282
            } else {
283
                v = *ptr++;
284
            }
285
            gif_put_bits_rev(&p, 9, v);
286
            if (--w == 0) {
287
                w = width;
288
                buf += linesize;
289
                ptr = buf;
290
            }
291
        }
292

    
293
        if(left<=GIF_CHUNKS) {
294
            gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
295
            gif_flush_put_bits_rev(&p);
296
        }
297
        if(pbBufPtr(&p) - p.buf > 0) {
298
            put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
299
            put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
300
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
301
        }
302
        left-=GIF_CHUNKS;
303
    }
304
    put_byte(pb, 0x00); /* end of image block */
305

    
306
    return 0;
307
}
308

    
309
typedef struct {
310
    int64_t time, file_time;
311
    uint8_t buffer[100]; /* data chunks */
312
} GIFContext;
313

    
314
static int gif_write_header(AVFormatContext *s)
315
{
316
    GIFContext *gif = s->priv_data;
317
    ByteIOContext *pb = &s->pb;
318
    AVCodecContext *enc, *video_enc;
319
    int i, width, height, loop_count /*, rate*/;
320

    
321
/* XXX: do we reject audio streams or just ignore them ?
322
    if(s->nb_streams > 1)
323
        return -1;
324
*/
325
    gif->time = 0;
326
    gif->file_time = 0;
327

    
328
    video_enc = NULL;
329
    for(i=0;i<s->nb_streams;i++) {
330
        enc = s->streams[i]->codec;
331
        if (enc->codec_type != CODEC_TYPE_AUDIO)
332
            video_enc = enc;
333
    }
334

    
335
    if (!video_enc) {
336
        av_free(gif);
337
        return -1;
338
    } else {
339
        width = video_enc->width;
340
        height = video_enc->height;
341
        loop_count = s->loop_output;
342
//        rate = video_enc->time_base.den;
343
    }
344

    
345
    /* XXX: is it allowed ? seems to work so far... */
346
    video_enc->pix_fmt = PIX_FMT_RGB24;
347

    
348
    gif_image_write_header(pb, width, height, loop_count, NULL);
349

    
350
    put_flush_packet(&s->pb);
351
    return 0;
352
}
353

    
354
static int gif_write_video(AVFormatContext *s,
355
                           AVCodecContext *enc, const uint8_t *buf, int size)
356
{
357
    ByteIOContext *pb = &s->pb;
358
    GIFContext *gif = s->priv_data;
359
    int jiffies;
360
    int64_t delay;
361

    
362
    /* graphic control extension block */
363
    put_byte(pb, 0x21);
364
    put_byte(pb, 0xf9);
365
    put_byte(pb, 0x04); /* block size */
366
    put_byte(pb, 0x04); /* flags */
367

    
368
    /* 1 jiffy is 1/70 s */
369
    /* the delay_time field indicates the number of jiffies - 1 */
370
    delay = gif->file_time - gif->time;
371

    
372
    /* XXX: should use delay, in order to be more accurate */
373
    /* instead of using the same rounded value each time */
374
    /* XXX: don't even remember if I really use it for now */
375
    jiffies = (70*enc->time_base.num/enc->time_base.den) - 1;
376

    
377
    put_le16(pb, jiffies);
378

    
379
    put_byte(pb, 0x1f); /* transparent color index */
380
    put_byte(pb, 0x00);
381

    
382
    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
383
                          buf, enc->width * 3, PIX_FMT_RGB24);
384

    
385
    put_flush_packet(&s->pb);
386
    return 0;
387
}
388

    
389
static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
390
{
391
    AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
392
    if (codec->codec_type == CODEC_TYPE_AUDIO)
393
        return 0; /* just ignore audio */
394
    else
395
        return gif_write_video(s, codec, pkt->data, pkt->size);
396
}
397

    
398
static int gif_write_trailer(AVFormatContext *s)
399
{
400
    ByteIOContext *pb = &s->pb;
401

    
402
    put_byte(pb, 0x3b);
403
    put_flush_packet(&s->pb);
404
    return 0;
405
}
406

    
407
/* better than nothing gif image writer */
408
int gif_write(ByteIOContext *pb, AVImageInfo *info)
409
{
410
    gif_image_write_header(pb, info->width, info->height, AVFMT_NOOUTPUTLOOP,
411
                           (uint32_t *)info->pict.data[1]);
412
    gif_image_write_image(pb, 0, 0, info->width, info->height,
413
                          info->pict.data[0], info->pict.linesize[0],
414
                          PIX_FMT_PAL8);
415
    put_byte(pb, 0x3b);
416
    put_flush_packet(pb);
417
    return 0;
418
}
419

    
420
static AVOutputFormat gif_oformat = {
421
    "gif",
422
    "GIF Animation",
423
    "image/gif",
424
    "gif",
425
    sizeof(GIFContext),
426
    CODEC_ID_NONE,
427
    CODEC_ID_RAWVIDEO,
428
    gif_write_header,
429
    gif_write_packet,
430
    gif_write_trailer,
431
};
432

    
433
extern AVInputFormat gif_iformat;
434

    
435
int gif_init(void)
436
{
437
    av_register_output_format(&gif_oformat);
438
    av_register_input_format(&gif_iformat);
439
    return 0;
440
}