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ffmpeg / libav / gif.c @ 84082497

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1
/*
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 * Animated GIF encoder
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 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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 */
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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.
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 */
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#include "avformat.h"
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/* bitstream minipacket size */
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#define GIF_CHUNKS 100
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/* slows down the decoding (and some browsers doesn't like it) */
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/* #define GIF_ADD_APP_HEADER */
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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;
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} rgb_triplet;
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/* we use the standard 216 color palette */
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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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 */
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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 },
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    { 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 },
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    { 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 },
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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 },
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    { 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 },
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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 },
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};
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/* The GIF format uses reversed order for bitstreams... */
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/* at least they don't use PDP_ENDIAN :) */
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/* so we 'extend' PutBitContext. hmmm, OOP :) */
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/* seems this thing changed slightly since I wrote it... */
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105
#ifdef ALT_BITSTREAM_WRITER
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# error no ALT_BITSTREAM_WRITER support for now
107
#endif
108

    
109
static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
110
{
111
    unsigned int bit_buf;
112
    int bit_cnt;
113

    
114
#ifdef STATS
115
    st_out_bit_counts[st_current_index] += n;
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#endif
117
    //    printf("put_bits=%d %x\n", n, value);
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    assert(n == 32 || value < (1U << n));
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    bit_buf = s->bit_buf;
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    bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
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    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
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    /* XXX: optimize */
125
    if (n < (32-bit_cnt)) {
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        bit_buf |= value << (bit_cnt);
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        bit_cnt+=n;
128
    } else {
129
        bit_buf |= value << (bit_cnt);
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131
        *s->buf_ptr = bit_buf & 0xff;
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        s->buf_ptr[1] = (bit_buf >> 8) & 0xff;
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        s->buf_ptr[2] = (bit_buf >> 16) & 0xff;
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        s->buf_ptr[3] = (bit_buf >> 24) & 0xff;
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        //printf("bitbuf = %08x\n", bit_buf);
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        s->buf_ptr+=4;
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        if (s->buf_ptr >= s->buf_end)
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            puts("bit buffer overflow !!"); // should never happen ! who got rid of the callback ???
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//            flush_buffer_rev(s);
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        bit_cnt=bit_cnt + n - 32;
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        if (bit_cnt == 0) {
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            bit_buf = 0;
144
        } else {
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            bit_buf = value >> (n - bit_cnt);
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        }
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    }
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    s->bit_buf = bit_buf;
150
    s->bit_left = 32 - bit_cnt;
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}
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/* pad the end of the output stream with zeros */
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static void gif_flush_put_bits_rev(PutBitContext *s)
155
{
156
    while (s->bit_left < 32) {
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        /* XXX: should test end of buffer */
158
        *s->buf_ptr++=s->bit_buf & 0xff;
159
        s->bit_buf>>=8;
160
        s->bit_left+=8;
161
    }
162
//    flush_buffer_rev(s);
163
    s->bit_left=32;
164
    s->bit_buf=0;
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}
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/* !RevPutBitContext */
168

    
169
typedef struct {
170
    UINT8 buffer[100]; /* data chunks */
171
    INT64 time, file_time;
172
} GIFContext;
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static int gif_write_header(AVFormatContext *s)
175
{
176
    GIFContext *gif = s->priv_data;
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    ByteIOContext *pb = &s->pb;
178
    AVCodecContext *enc, *video_enc;
179
    int i, width, height, rate;
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/* XXX: do we reject audio streams or just ignore them ?
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    if(s->nb_streams > 1)
183
        return -1;
184
*/
185
    gif->time = 0;
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    gif->file_time = 0;
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    video_enc = NULL;
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    for(i=0;i<s->nb_streams;i++) {
190
        enc = &s->streams[i]->codec;
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        if (enc->codec_type != CODEC_TYPE_AUDIO)
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            video_enc = enc;
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    }
194

    
195
    if (!video_enc) {
196
        av_free(gif);
197
        return -1;
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    } else {
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        width = video_enc->width;
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        height = video_enc->height;
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        rate = video_enc->frame_rate;
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    }
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    /* XXX: is it allowed ? seems to work so far... */
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    video_enc->pix_fmt = PIX_FMT_RGB24;
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    /* GIF header */
208

    
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    put_tag(pb, "GIF");
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    put_tag(pb, "89a");
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    put_le16(pb, width);
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    put_le16(pb, height);
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    put_byte(pb, 0xf7); /* flags: global clut, 256 entries */
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    put_byte(pb, 0x1f); /* background color index */
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    put_byte(pb, 0); /* aspect ratio */
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    /* the global palette */
219

    
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    put_buffer(pb, (unsigned char *)gif_clut, 216*3);
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    for(i=0;i<((256-216)*3);i++)
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       put_byte(pb, 0);
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224
    /* application extension header */
225
    /* XXX: not really sure what to put in here... */
226
#ifdef GIF_ADD_APP_HEADER
227
    put_byte(pb, 0x21);
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    put_byte(pb, 0xff);
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    put_byte(pb, 0x0b);
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    put_tag(pb, "NETSCAPE2.0");
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    put_byte(pb, 0x03);
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    put_byte(pb, 0x01);
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    put_byte(pb, 0x00);
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    put_byte(pb, 0x00);
235
#endif
236

    
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    put_flush_packet(&s->pb);
238
    return 0;
239
}
240

    
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/* this is maybe slow, but allows for extensions */
242
static inline unsigned char gif_clut_index(rgb_triplet *clut, UINT8 r, UINT8 g, UINT8 b)
243
{
244
    return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
245
}
246

    
247
/* chunk writer callback */
248
/* !!! XXX:deprecated
249
static void gif_put_chunk(void *pbctx, UINT8 *buffer, int count)
250
{
251
    ByteIOContext *pb = (ByteIOContext *)pbctx;
252
    put_byte(pb, (UINT8)count);
253
    put_buffer(pb, buffer, count);
254
}
255
*/
256

    
257
static int gif_write_video(AVFormatContext *s, 
258
                           AVCodecContext *enc, UINT8 *buf, int size)
259
{
260
    ByteIOContext *pb = &s->pb;
261
    GIFContext *gif = s->priv_data;
262
    int i, left, jiffies;
263
    INT64 delay;
264
    PutBitContext p;
265
    UINT8 buffer[200]; /* 100 * 9 / 8 = 113 */
266

    
267

    
268
    /* graphic control extension block */
269
    put_byte(pb, 0x21);
270
    put_byte(pb, 0xf9);
271
    put_byte(pb, 0x04); /* block size */
272
    put_byte(pb, 0x04); /* flags */
273
    
274
    /* 1 jiffy is 1/70 s */
275
    /* the delay_time field indicates the number of jiffies - 1 */
276
    delay = gif->file_time - gif->time;
277

    
278
    /* XXX: should use delay, in order to be more accurate */
279
    /* instead of using the same rounded value each time */
280
    /* XXX: don't even remember if I really use it for now */
281
    jiffies = (70*FRAME_RATE_BASE/enc->frame_rate) - 1;
282

    
283
    put_le16(pb, jiffies);
284

    
285
    put_byte(pb, 0x1f); /* transparent color index */
286
    put_byte(pb, 0x00);
287

    
288
    /* image block */
289

    
290
    put_byte(pb, 0x2c);
291
    put_le16(pb, 0);
292
    put_le16(pb, 0);
293
    put_le16(pb, enc->width);
294
    put_le16(pb, enc->height);
295
    put_byte(pb, 0x00); /* flags */
296
    /* no local clut */
297

    
298
    put_byte(pb, 0x08);
299

    
300
    left=size/3;
301

    
302
    init_put_bits(&p, buffer, 130, NULL, NULL);
303

    
304
/*
305
 * the thing here is the bitstream is written as little packets, with a size byte before
306
 * but it's still the same bitstream between packets (no flush !)
307
 */
308

    
309
    while(left>0) {
310

    
311
        gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
312

    
313
        for(i=0;i<GIF_CHUNKS;i++) {
314
            gif_put_bits_rev(&p, 9, gif_clut_index(NULL, *buf, buf[1], buf[2]));
315
            buf+=3;
316
        }
317

    
318
        if(left<=GIF_CHUNKS) {
319
            gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
320
            gif_flush_put_bits_rev(&p);
321
        }
322
        if(pbBufPtr(&p) - p.buf > 0) {
323
            put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
324
            put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
325
            p.data_out_size += pbBufPtr(&p) - p.buf;
326
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
327
        }
328
        if(left<=GIF_CHUNKS) {
329
            put_byte(pb, 0x00); /* end of image block */
330
        }
331

    
332
        left-=GIF_CHUNKS;
333
    }
334

    
335
    put_flush_packet(&s->pb);
336
    return 0;
337
}
338

    
339
static int gif_write_packet(AVFormatContext *s, int stream_index, 
340
                           UINT8 *buf, int size, int force_pts)
341
{
342
    AVCodecContext *codec = &s->streams[stream_index]->codec;
343
    if (codec->codec_type == CODEC_TYPE_AUDIO)
344
        return 0; /* just ignore audio */
345
    else
346
        return gif_write_video(s, codec, buf, size);
347
}
348

    
349
static int gif_write_trailer(AVFormatContext *s)
350
{
351
    ByteIOContext *pb = &s->pb;
352

    
353
    put_byte(pb, 0x3b);
354
    put_flush_packet(&s->pb);
355
    return 0;
356
}
357

    
358
static AVOutputFormat gif_oformat = {
359
    "gif",
360
    "GIF Animation",
361
    "image/gif",
362
    "gif",
363
    sizeof(GIFContext),
364
    CODEC_ID_NONE,
365
    CODEC_ID_RAWVIDEO,
366
    gif_write_header,
367
    gif_write_packet,
368
    gif_write_trailer,
369
};
370

    
371
int gif_init(void)
372
{
373
    av_register_output_format(&gif_oformat);
374
    return 0;
375
}