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/*
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 * GIF encoder.
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 * Copyright (c) 2000 Fabrice Bellard.
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 * Copyright (c) 2002 Francois Revol.
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 * Copyright (c) 2006 Baptiste Coudurier.
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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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 */
23

    
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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 "avcodec.h"
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#include "bytestream.h"
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#include "bitstream.h"
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/* bitstream minipacket size */
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#define GIF_CHUNKS 100
50

    
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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
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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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 */
67

    
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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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107
/* 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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#ifdef ALT_BITSTREAM_WRITER
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# error no ALT_BITSTREAM_WRITER support for now
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#endif
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static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
117
{
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    unsigned int bit_buf;
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    int bit_cnt;
120

    
121
    //    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);
128
    /* XXX: optimize */
129
    if (n < (32-bit_cnt)) {
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        bit_buf |= value << (bit_cnt);
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        bit_cnt+=n;
132
    } else {
133
        bit_buf |= value << (bit_cnt);
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        *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;
148
        } else {
149
            bit_buf = value >> (n - bit_cnt);
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        }
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    }
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    s->bit_buf = bit_buf;
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    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)
159
{
160
    while (s->bit_left < 32) {
161
        /* XXX: should test end of buffer */
162
        *s->buf_ptr++=s->bit_buf & 0xff;
163
        s->bit_buf>>=8;
164
        s->bit_left+=8;
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    }
166
//    flush_buffer_rev(s);
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    s->bit_left=32;
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    s->bit_buf=0;
169
}
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/* !RevPutBitContext */
172

    
173
/* GIF header */
174
static int gif_image_write_header(uint8_t **bytestream,
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                                  int width, int height, int loop_count,
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                                  uint32_t *palette)
177
{
178
    int i;
179
    unsigned int v;
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181
    bytestream_put_buffer(bytestream, "GIF", 3);
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    bytestream_put_buffer(bytestream, "89a", 3);
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    bytestream_put_le16(bytestream, width);
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    bytestream_put_le16(bytestream, height);
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    bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
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    bytestream_put_byte(bytestream, 0x1f); /* background color index */
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    bytestream_put_byte(bytestream, 0); /* aspect ratio */
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    /* the global palette */
191
    if (!palette) {
192
        bytestream_put_buffer(bytestream, (const unsigned char *)gif_clut, 216*3);
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        for(i=0;i<((256-216)*3);i++)
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            bytestream_put_byte(bytestream, 0);
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    } else {
196
        for(i=0;i<256;i++) {
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            v = palette[i];
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            bytestream_put_byte(bytestream, (v >> 16) & 0xff);
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            bytestream_put_byte(bytestream, (v >> 8) & 0xff);
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            bytestream_put_byte(bytestream, (v) & 0xff);
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        }
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    }
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        /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
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                see http://members.aol.com/royalef/gifabout.htm#net-extension
206

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                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)
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                byte  16       : 1 (hex 0x01)
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                bytes 17 to 18 : 0 to 65535, an unsigned integer in
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                                         lo-hi byte format. This indicate the
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                                         number of iterations the loop should
219
                                         be executed.
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                bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
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        */
222

    
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    /* application extension header */
224
#ifdef GIF_ADD_APP_HEADER
225
    if (loop_count >= 0 && loop_count <= 65535) {
226
        bytestream_put_byte(bytestream, 0x21);
227
        bytestream_put_byte(bytestream, 0xff);
228
        bytestream_put_byte(bytestream, 0x0b);
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        bytestream_put_buffer(bytestream, "NETSCAPE2.0", 11);  // bytes 4 to 14
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        bytestream_put_byte(bytestream, 0x03); // byte 15
231
        bytestream_put_byte(bytestream, 0x01); // byte 16
232
        bytestream_put_le16(bytestream, (uint16_t)loop_count);
233
        bytestream_put_byte(bytestream, 0x00); // byte 19
234
    }
235
#endif
236
    return 0;
237
}
238

    
239
/* this is maybe slow, but allows for extensions */
240
static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
241
{
242
    return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
243
}
244

    
245

    
246
static int gif_image_write_image(uint8_t **bytestream,
247
                                 int x1, int y1, int width, int height,
248
                                 const uint8_t *buf, int linesize, int pix_fmt)
249
{
250
    PutBitContext p;
251
    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
252
    int i, left, w, v;
253
    const uint8_t *ptr;
254
    /* image block */
255

    
256
    bytestream_put_byte(bytestream, 0x2c);
257
    bytestream_put_le16(bytestream, x1);
258
    bytestream_put_le16(bytestream, y1);
259
    bytestream_put_le16(bytestream, width);
260
    bytestream_put_le16(bytestream, height);
261
    bytestream_put_byte(bytestream, 0x00); /* flags */
262
    /* no local clut */
263

    
264
    bytestream_put_byte(bytestream, 0x08);
265

    
266
    left= width * height;
267

    
268
    init_put_bits(&p, buffer, 130);
269

    
270
/*
271
 * the thing here is the bitstream is written as little packets, with a size byte before
272
 * but it's still the same bitstream between packets (no flush !)
273
 */
274
    ptr = buf;
275
    w = width;
276
    while(left>0) {
277

    
278
        gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
279

    
280
        for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
281
            if (pix_fmt == PIX_FMT_RGB24) {
282
                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
283
                ptr+=3;
284
            } else {
285
                v = *ptr++;
286
            }
287
            gif_put_bits_rev(&p, 9, v);
288
            if (--w == 0) {
289
                w = width;
290
                buf += linesize;
291
                ptr = buf;
292
            }
293
        }
294

    
295
        if(left<=GIF_CHUNKS) {
296
            gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
297
            gif_flush_put_bits_rev(&p);
298
        }
299
        if(pbBufPtr(&p) - p.buf > 0) {
300
            bytestream_put_byte(bytestream, pbBufPtr(&p) - p.buf); /* byte count of the packet */
301
            bytestream_put_buffer(bytestream, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
302
            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
303
        }
304
        left-=GIF_CHUNKS;
305
    }
306
    bytestream_put_byte(bytestream, 0x00); /* end of image block */
307
    bytestream_put_byte(bytestream, 0x3b);
308
    return 0;
309
}
310

    
311
typedef struct {
312
    int64_t time, file_time;
313
    uint8_t buffer[100]; /* data chunks */
314
    AVFrame picture;
315
} GIFContext;
316

    
317
static int gif_encode_init(AVCodecContext *avctx)
318
{
319
    GIFContext *s = avctx->priv_data;
320

    
321
    avctx->coded_frame = &s->picture;
322
    return 0;
323
}
324

    
325
/* better than nothing gif encoder */
326
static int gif_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int buf_size, void *data)
327
{
328
    GIFContext *s = avctx->priv_data;
329
    AVFrame *pict = data;
330
    AVFrame *const p = (AVFrame *)&s->picture;
331
    uint8_t *outbuf_ptr = outbuf;
332

    
333
    *p = *pict;
334
    p->pict_type = FF_I_TYPE;
335
    p->key_frame = 1;
336
    gif_image_write_header(&outbuf_ptr, avctx->width, avctx->height, -1, (uint32_t *)pict->data[1]);
337
    gif_image_write_image(&outbuf_ptr, 0, 0, avctx->width, avctx->height, pict->data[0], pict->linesize[0], PIX_FMT_PAL8);
338
    return outbuf_ptr - outbuf;
339
}
340

    
341
AVCodec gif_encoder = {
342
    "gif",
343
    CODEC_TYPE_VIDEO,
344
    CODEC_ID_GIF,
345
    sizeof(GIFContext),
346
    gif_encode_init,
347
    gif_encode_frame,
348
    NULL, //encode_end,
349
    .pix_fmts= (enum PixelFormat[]){PIX_FMT_PAL8, -1},
350
};