359 lines
14 KiB
C
359 lines
14 KiB
C
/*
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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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*/
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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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/* 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
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#include "libavcodec/put_bits.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 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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*/
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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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/* GIF header */
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static int gif_image_write_header(AVIOContext *pb,
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int width, int height, int loop_count,
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uint32_t *palette)
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{
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int i;
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unsigned int v;
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avio_write(pb, "GIF", 3);
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avio_write(pb, "89a", 3);
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avio_wl16(pb, width);
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avio_wl16(pb, height);
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avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
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avio_w8(pb, 0x1f); /* background color index */
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avio_w8(pb, 0); /* aspect ratio */
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/* the global palette */
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if (!palette) {
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avio_write(pb, (const unsigned char *)gif_clut, 216*3);
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for(i=0;i<((256-216)*3);i++)
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avio_w8(pb, 0);
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} else {
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for(i=0;i<256;i++) {
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v = palette[i];
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avio_w8(pb, (v >> 16) & 0xff);
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avio_w8(pb, (v >> 8) & 0xff);
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avio_w8(pb, (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
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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
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be executed.
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bytes 19 : 0 (hex 0x00) a Data Sub-block Terminator
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*/
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/* application extension header */
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#ifdef GIF_ADD_APP_HEADER
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if (loop_count >= 0 && loop_count <= 65535) {
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avio_w8(pb, 0x21);
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avio_w8(pb, 0xff);
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avio_w8(pb, 0x0b);
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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
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avio_wl16(pb, (uint16_t)loop_count);
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avio_w8(pb, 0x00); // byte 19
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}
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#endif
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return 0;
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}
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/* this is maybe slow, but allows for extensions */
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static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
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{
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return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6);
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}
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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)
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{
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PutBitContext p;
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uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
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int i, left, w, v;
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const uint8_t *ptr;
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/* image block */
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avio_w8(pb, 0x2c);
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avio_wl16(pb, x1);
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avio_wl16(pb, y1);
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avio_wl16(pb, width);
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avio_wl16(pb, height);
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avio_w8(pb, 0x00); /* flags */
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/* no local clut */
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avio_w8(pb, 0x08);
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left= width * height;
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init_put_bits(&p, buffer, 130);
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/*
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* the thing here is the bitstream is written as little packets, with a size byte before
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* but it's still the same bitstream between packets (no flush !)
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*/
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ptr = buf;
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w = width;
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while(left>0) {
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put_bits(&p, 9, 0x0100); /* clear code */
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for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
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if (pix_fmt == PIX_FMT_RGB24) {
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v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
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ptr+=3;
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} else {
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v = *ptr++;
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}
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put_bits(&p, 9, v);
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if (--w == 0) {
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w = width;
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buf += linesize;
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ptr = buf;
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}
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}
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if(left<=GIF_CHUNKS) {
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put_bits(&p, 9, 0x101); /* end of stream */
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flush_put_bits(&p);
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}
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if(put_bits_ptr(&p) - p.buf > 0) {
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avio_w8(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
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avio_write(pb, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */
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p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
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}
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left-=GIF_CHUNKS;
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}
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avio_w8(pb, 0x00); /* end of image block */
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return 0;
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}
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typedef struct {
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int64_t time, file_time;
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uint8_t buffer[100]; /* data chunks */
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} GIFContext;
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static int gif_write_header(AVFormatContext *s)
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{
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GIFContext *gif = s->priv_data;
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AVIOContext *pb = s->pb;
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AVCodecContext *enc, *video_enc;
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int i, width, height, loop_count /*, rate*/;
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/* XXX: do we reject audio streams or just ignore them ?
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if(s->nb_streams > 1)
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return -1;
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*/
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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++) {
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enc = s->streams[i]->codec;
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if (enc->codec_type != AVMEDIA_TYPE_AUDIO)
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video_enc = enc;
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}
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if (!video_enc) {
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av_free(gif);
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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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loop_count = s->loop_output;
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// rate = video_enc->time_base.den;
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}
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if (video_enc->pix_fmt != PIX_FMT_RGB24) {
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av_log(s, AV_LOG_ERROR, "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");
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return AVERROR(EIO);
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}
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gif_image_write_header(pb, width, height, loop_count, NULL);
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avio_flush(s->pb);
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return 0;
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}
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static int gif_write_video(AVFormatContext *s,
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AVCodecContext *enc, const uint8_t *buf, int size)
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{
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AVIOContext *pb = s->pb;
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GIFContext *gif = s->priv_data;
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int jiffies;
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int64_t delay;
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/* graphic control extension block */
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avio_w8(pb, 0x21);
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avio_w8(pb, 0xf9);
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avio_w8(pb, 0x04); /* block size */
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avio_w8(pb, 0x04); /* flags */
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/* 1 jiffy is 1/70 s */
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/* the delay_time field indicates the number of jiffies - 1 */
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delay = gif->file_time - gif->time;
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/* XXX: should use delay, in order to be more accurate */
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/* instead of using the same rounded value each time */
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/* XXX: don't even remember if I really use it for now */
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jiffies = (70*enc->time_base.num/enc->time_base.den) - 1;
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avio_wl16(pb, jiffies);
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avio_w8(pb, 0x1f); /* transparent color index */
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avio_w8(pb, 0x00);
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gif_image_write_image(pb, 0, 0, enc->width, enc->height,
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buf, enc->width * 3, PIX_FMT_RGB24);
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avio_flush(s->pb);
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return 0;
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}
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static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
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{
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AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
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if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
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return 0; /* just ignore audio */
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else
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return gif_write_video(s, codec, pkt->data, pkt->size);
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}
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static int gif_write_trailer(AVFormatContext *s)
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{
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AVIOContext *pb = s->pb;
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avio_w8(pb, 0x3b);
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avio_flush(s->pb);
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return 0;
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}
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AVOutputFormat ff_gif_muxer = {
|
|
"gif",
|
|
NULL_IF_CONFIG_SMALL("GIF Animation"),
|
|
"image/gif",
|
|
"gif",
|
|
sizeof(GIFContext),
|
|
CODEC_ID_NONE,
|
|
CODEC_ID_RAWVIDEO,
|
|
gif_write_header,
|
|
gif_write_packet,
|
|
gif_write_trailer,
|
|
};
|