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ffmpeg / libavformat / gif.c @ a1b79792

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1
/*
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 * Animated GIF muxer
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 * 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"
43

    
44
/* The GIF format uses reversed order for bitstreams... */
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/* at least they don't use PDP_ENDIAN :) */
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#define BITSTREAM_WRITER_LE
47

    
48
#include "libavcodec/put_bits.h"
49

    
50
/* bitstream minipacket size */
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#define GIF_CHUNKS 100
52

    
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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
56

    
57
typedef struct {
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    unsigned char r;
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    unsigned char g;
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    unsigned char b;
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} rgb_triplet;
62

    
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/* we use the standard 216 color palette */
64

    
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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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 */
69

    
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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 },
73
    { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
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    { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
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    { 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 },
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    { 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 },
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    { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
80
    { 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 },
82
    { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
83
    { 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 },
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    { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
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    { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
89
    { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
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    { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
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    { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
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    { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
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    { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
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    { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
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    { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
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    { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
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    { 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 },
100
    { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
101
    { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
102
    { 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 },
107
};
108

    
109
/* GIF header */
110
static int gif_image_write_header(AVIOContext *pb,
111
                                  int width, int height, int loop_count,
112
                                  uint32_t *palette)
113
{
114
    int i;
115
    unsigned int v;
116

    
117
    avio_write(pb, "GIF", 3);
118
    avio_write(pb, "89a", 3);
119
    avio_wl16(pb, width);
120
    avio_wl16(pb, height);
121

    
122
    avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
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    avio_w8(pb, 0x1f); /* background color index */
124
    avio_w8(pb, 0);    /* aspect ratio */
125

    
126
    /* the global palette */
127
    if (!palette) {
128
        avio_write(pb, (const unsigned char *)gif_clut, 216*3);
129
        for(i=0;i<((256-216)*3);i++)
130
            avio_w8(pb, 0);
131
    } else {
132
        for(i=0;i<256;i++) {
133
            v = palette[i];
134
            avio_w8(pb, (v >> 16) & 0xff);
135
            avio_w8(pb, (v >> 8) & 0xff);
136
            avio_w8(pb, (v) & 0xff);
137
        }
138
    }
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140
        /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
141
                see http://members.aol.com/royalef/gifabout.htm#net-extension
142

143
                byte   1       : 33 (hex 0x21) GIF Extension code
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                byte   2       : 255 (hex 0xFF) Application Extension Label
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                byte   3       : 11 (hex (0x0B) Length of Application Block
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                                         (eleven bytes of data to follow)
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                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)
151
                byte  16       : 1 (hex 0x01)
152
                bytes 17 to 18 : 0 to 65535, an unsigned integer in
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                                         lo-hi byte format. This indicate the
154
                                         number of iterations the loop should
155
                                         be executed.
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                bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
157
        */
158

    
159
    /* application extension header */
160
#ifdef GIF_ADD_APP_HEADER
161
    if (loop_count >= 0 && loop_count <= 65535) {
162
    avio_w8(pb, 0x21);
163
    avio_w8(pb, 0xff);
164
    avio_w8(pb, 0x0b);
165
        avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);  // bytes 4 to 14
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        avio_w8(pb, 0x03); // byte 15
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        avio_w8(pb, 0x01); // byte 16
168
        avio_wl16(pb, (uint16_t)loop_count);
169
        avio_w8(pb, 0x00); // byte 19
170
    }
171
#endif
172
    return 0;
173
}
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175
/* this is maybe slow, but allows for extensions */
176
static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
177
{
178
    return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6);
179
}
180

    
181

    
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static int gif_image_write_image(AVIOContext *pb,
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                                 int x1, int y1, int width, int height,
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                                 const uint8_t *buf, int linesize, int pix_fmt)
185
{
186
    PutBitContext p;
187
    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
188
    int i, left, w, v;
189
    const uint8_t *ptr;
190
    /* image block */
191

    
192
    avio_w8(pb, 0x2c);
193
    avio_wl16(pb, x1);
194
    avio_wl16(pb, y1);
195
    avio_wl16(pb, width);
196
    avio_wl16(pb, height);
197
    avio_w8(pb, 0x00); /* flags */
198
    /* no local clut */
199

    
200
    avio_w8(pb, 0x08);
201

    
202
    left= width * height;
203

    
204
    init_put_bits(&p, buffer, 130);
205

    
206
/*
207
 * the thing here is the bitstream is written as little packets, with a size byte before
208
 * but it's still the same bitstream between packets (no flush !)
209
 */
210
    ptr = buf;
211
    w = width;
212
    while(left>0) {
213

    
214
        put_bits(&p, 9, 0x0100); /* clear code */
215

    
216
        for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
217
            if (pix_fmt == PIX_FMT_RGB24) {
218
                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
219
                ptr+=3;
220
            } else {
221
                v = *ptr++;
222
            }
223
            put_bits(&p, 9, v);
224
            if (--w == 0) {
225
                w = width;
226
                buf += linesize;
227
                ptr = buf;
228
            }
229
        }
230

    
231
        if(left<=GIF_CHUNKS) {
232
            put_bits(&p, 9, 0x101); /* end of stream */
233
            flush_put_bits(&p);
234
        }
235
        if(put_bits_ptr(&p) - p.buf > 0) {
236
            avio_w8(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
237
            avio_write(pb, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */
238
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
239
        }
240
        left-=GIF_CHUNKS;
241
    }
242
    avio_w8(pb, 0x00); /* end of image block */
243

    
244
    return 0;
245
}
246

    
247
typedef struct {
248
    int64_t time, file_time;
249
    uint8_t buffer[100]; /* data chunks */
250
} GIFContext;
251

    
252
static int gif_write_header(AVFormatContext *s)
253
{
254
    GIFContext *gif = s->priv_data;
255
    AVIOContext *pb = s->pb;
256
    AVCodecContext *enc, *video_enc;
257
    int i, width, height, loop_count /*, rate*/;
258

    
259
/* XXX: do we reject audio streams or just ignore them ?
260
    if(s->nb_streams > 1)
261
        return -1;
262
*/
263
    gif->time = 0;
264
    gif->file_time = 0;
265

    
266
    video_enc = NULL;
267
    for(i=0;i<s->nb_streams;i++) {
268
        enc = s->streams[i]->codec;
269
        if (enc->codec_type != AVMEDIA_TYPE_AUDIO)
270
            video_enc = enc;
271
    }
272

    
273
    if (!video_enc) {
274
        av_free(gif);
275
        return -1;
276
    } else {
277
        width = video_enc->width;
278
        height = video_enc->height;
279
        loop_count = s->loop_output;
280
//        rate = video_enc->time_base.den;
281
    }
282

    
283
    if (video_enc->pix_fmt != PIX_FMT_RGB24) {
284
        av_log(s, AV_LOG_ERROR, "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");
285
        return AVERROR(EIO);
286
    }
287

    
288
    gif_image_write_header(pb, width, height, loop_count, NULL);
289

    
290
    put_flush_packet(s->pb);
291
    return 0;
292
}
293

    
294
static int gif_write_video(AVFormatContext *s,
295
                           AVCodecContext *enc, const uint8_t *buf, int size)
296
{
297
    AVIOContext *pb = s->pb;
298
    GIFContext *gif = s->priv_data;
299
    int jiffies;
300
    int64_t delay;
301

    
302
    /* graphic control extension block */
303
    avio_w8(pb, 0x21);
304
    avio_w8(pb, 0xf9);
305
    avio_w8(pb, 0x04); /* block size */
306
    avio_w8(pb, 0x04); /* flags */
307

    
308
    /* 1 jiffy is 1/70 s */
309
    /* the delay_time field indicates the number of jiffies - 1 */
310
    delay = gif->file_time - gif->time;
311

    
312
    /* XXX: should use delay, in order to be more accurate */
313
    /* instead of using the same rounded value each time */
314
    /* XXX: don't even remember if I really use it for now */
315
    jiffies = (70*enc->time_base.num/enc->time_base.den) - 1;
316

    
317
    avio_wl16(pb, jiffies);
318

    
319
    avio_w8(pb, 0x1f); /* transparent color index */
320
    avio_w8(pb, 0x00);
321

    
322
    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
323
                          buf, enc->width * 3, PIX_FMT_RGB24);
324

    
325
    put_flush_packet(s->pb);
326
    return 0;
327
}
328

    
329
static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
330
{
331
    AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
332
    if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
333
        return 0; /* just ignore audio */
334
    else
335
        return gif_write_video(s, codec, pkt->data, pkt->size);
336
}
337

    
338
static int gif_write_trailer(AVFormatContext *s)
339
{
340
    AVIOContext *pb = s->pb;
341

    
342
    avio_w8(pb, 0x3b);
343
    put_flush_packet(s->pb);
344
    return 0;
345
}
346

    
347
AVOutputFormat ff_gif_muxer = {
348
    "gif",
349
    NULL_IF_CONFIG_SMALL("GIF Animation"),
350
    "image/gif",
351
    "gif",
352
    sizeof(GIFContext),
353
    CODEC_ID_NONE,
354
    CODEC_ID_RAWVIDEO,
355
    gif_write_header,
356
    gif_write_packet,
357
    gif_write_trailer,
358
};