1/* 2 * GIF encoder. 3 * Copyright (c) 2000 Fabrice Bellard 4 * Copyright (c) 2002 Francois Revol 5 * Copyright (c) 2006 Baptiste Coudurier 6 * 7 * This file is part of FFmpeg. 8 * 9 * FFmpeg is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU Lesser General Public 11 * License as published by the Free Software Foundation; either 12 * version 2.1 of the License, or (at your option) any later version. 13 * 14 * FFmpeg is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * Lesser General Public License for more details. 18 * 19 * You should have received a copy of the GNU Lesser General Public 20 * License along with FFmpeg; if not, write to the Free Software 21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 22 */ 23 24/* 25 * First version by Francois Revol revol@free.fr 26 * 27 * Features and limitations: 28 * - currently no compression is performed, 29 * in fact the size of the data is 9/8 the size of the image in 8bpp 30 * - uses only a global standard palette 31 * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS). 32 * 33 * Reference documents: 34 * http://www.goice.co.jp/member/mo/formats/gif.html 35 * http://astronomy.swin.edu.au/pbourke/dataformats/gif/ 36 * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt 37 * 38 * this url claims to have an LZW algorithm not covered by Unisys patent: 39 * http://www.msg.net/utility/whirlgif/gifencod.html 40 * could help reduce the size of the files _a lot_... 41 * some sites mentions an RLE type compression also. 42 */ 43 44#include "avcodec.h" 45#include "bytestream.h" 46 47/* The GIF format uses reversed order for bitstreams... */ 48/* at least they don't use PDP_ENDIAN :) */ 49#define BITSTREAM_WRITER_LE 50 51#include "bitstream.h" 52 53/* bitstream minipacket size */ 54#define GIF_CHUNKS 100 55 56/* GIF header */ 57static int gif_image_write_header(uint8_t **bytestream, 58 int width, int height, 59 uint32_t *palette) 60{ 61 int i; 62 unsigned int v; 63 64 bytestream_put_buffer(bytestream, "GIF", 3); 65 bytestream_put_buffer(bytestream, "89a", 3); 66 bytestream_put_le16(bytestream, width); 67 bytestream_put_le16(bytestream, height); 68 69 bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */ 70 bytestream_put_byte(bytestream, 0x1f); /* background color index */ 71 bytestream_put_byte(bytestream, 0); /* aspect ratio */ 72 73 /* the global palette */ 74 for(i=0;i<256;i++) { 75 v = palette[i]; 76 bytestream_put_be24(bytestream, v); 77 } 78 79 return 0; 80} 81 82static int gif_image_write_image(uint8_t **bytestream, 83 int x1, int y1, int width, int height, 84 const uint8_t *buf, int linesize, int pix_fmt) 85{ 86 PutBitContext p; 87 uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */ 88 int i, left, w; 89 const uint8_t *ptr; 90 /* image block */ 91 92 bytestream_put_byte(bytestream, 0x2c); 93 bytestream_put_le16(bytestream, x1); 94 bytestream_put_le16(bytestream, y1); 95 bytestream_put_le16(bytestream, width); 96 bytestream_put_le16(bytestream, height); 97 bytestream_put_byte(bytestream, 0x00); /* flags */ 98 /* no local clut */ 99 100 bytestream_put_byte(bytestream, 0x08); 101 102 left= width * height; 103 104 init_put_bits(&p, buffer, 130); 105 106/* 107 * the thing here is the bitstream is written as little packets, with a size byte before 108 * but it's still the same bitstream between packets (no flush !) 109 */ 110 ptr = buf; 111 w = width; 112 while(left>0) { 113 114 put_bits(&p, 9, 0x0100); /* clear code */ 115 116 for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) { 117 put_bits(&p, 9, *ptr++); 118 if (--w == 0) { 119 w = width; 120 buf += linesize; 121 ptr = buf; 122 } 123 } 124 125 if(left<=GIF_CHUNKS) { 126 put_bits(&p, 9, 0x101); /* end of stream */ 127 flush_put_bits(&p); 128 } 129 if(pbBufPtr(&p) - p.buf > 0) { 130 bytestream_put_byte(bytestream, pbBufPtr(&p) - p.buf); /* byte count of the packet */ 131 bytestream_put_buffer(bytestream, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */ 132 p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */ 133 } 134 left-=GIF_CHUNKS; 135 } 136 bytestream_put_byte(bytestream, 0x00); /* end of image block */ 137 bytestream_put_byte(bytestream, 0x3b); 138 return 0; 139} 140 141typedef struct { 142 AVFrame picture; 143} GIFContext; 144 145static av_cold int gif_encode_init(AVCodecContext *avctx) 146{ 147 GIFContext *s = avctx->priv_data; 148 149 avctx->coded_frame = &s->picture; 150 return 0; 151} 152 153/* better than nothing gif encoder */ 154static int gif_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int buf_size, void *data) 155{ 156 GIFContext *s = avctx->priv_data; 157 AVFrame *pict = data; 158 AVFrame *const p = (AVFrame *)&s->picture; 159 uint8_t *outbuf_ptr = outbuf; 160 161 *p = *pict; 162 p->pict_type = FF_I_TYPE; 163 p->key_frame = 1; 164 gif_image_write_header(&outbuf_ptr, avctx->width, avctx->height, (uint32_t *)pict->data[1]); 165 gif_image_write_image(&outbuf_ptr, 0, 0, avctx->width, avctx->height, pict->data[0], pict->linesize[0], PIX_FMT_PAL8); 166 return outbuf_ptr - outbuf; 167} 168 169AVCodec gif_encoder = { 170 "gif", 171 CODEC_TYPE_VIDEO, 172 CODEC_ID_GIF, 173 sizeof(GIFContext), 174 gif_encode_init, 175 gif_encode_frame, 176 NULL, //encode_end, 177 .pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB8, PIX_FMT_BGR8, PIX_FMT_RGB4_BYTE, PIX_FMT_BGR4_BYTE, PIX_FMT_GRAY8, PIX_FMT_PAL8, PIX_FMT_NONE}, 178 .long_name= NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"), 179}; 180