/* * GIF encoder. * Copyright (c) 2000 Fabrice Bellard * Copyright (c) 2002 Francois Revol * Copyright (c) 2006 Baptiste Coudurier * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /* * First version by Francois Revol revol@free.fr * * Features and limitations: * - currently no compression is performed, * in fact the size of the data is 9/8 the size of the image in 8bpp * - uses only a global standard palette * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS). * * Reference documents: * http://www.goice.co.jp/member/mo/formats/gif.html * http://astronomy.swin.edu.au/pbourke/dataformats/gif/ * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt * * this url claims to have an LZW algorithm not covered by Unisys patent: * http://www.msg.net/utility/whirlgif/gifencod.html * could help reduce the size of the files _a lot_... * some sites mentions an RLE type compression also. */ #include "avcodec.h" #include "bytestream.h" /* The GIF format uses reversed order for bitstreams... */ /* at least they don't use PDP_ENDIAN :) */ #define BITSTREAM_WRITER_LE #include "put_bits.h" /* bitstream minipacket size */ #define GIF_CHUNKS 100 /* GIF header */ static int gif_image_write_header(uint8_t **bytestream, int width, int height, uint32_t *palette) { int i; unsigned int v; bytestream_put_buffer(bytestream, "GIF", 3); bytestream_put_buffer(bytestream, "89a", 3); bytestream_put_le16(bytestream, width); bytestream_put_le16(bytestream, height); bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */ bytestream_put_byte(bytestream, 0x1f); /* background color index */ bytestream_put_byte(bytestream, 0); /* aspect ratio */ /* the global palette */ for(i=0;i<256;i++) { v = palette[i]; bytestream_put_be24(bytestream, v); } return 0; } static int gif_image_write_image(uint8_t **bytestream, int x1, int y1, int width, int height, const uint8_t *buf, int linesize, int pix_fmt) { PutBitContext p; uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */ int i, left, w; const uint8_t *ptr; /* image block */ bytestream_put_byte(bytestream, 0x2c); bytestream_put_le16(bytestream, x1); bytestream_put_le16(bytestream, y1); bytestream_put_le16(bytestream, width); bytestream_put_le16(bytestream, height); bytestream_put_byte(bytestream, 0x00); /* flags */ /* no local clut */ bytestream_put_byte(bytestream, 0x08); left= width * height; init_put_bits(&p, buffer, 130); /* * the thing here is the bitstream is written as little packets, with a size byte before * but it's still the same bitstream between packets (no flush !) */ ptr = buf; w = width; while(left>0) { put_bits(&p, 9, 0x0100); /* clear code */ for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) { put_bits(&p, 9, *ptr++); if (--w == 0) { w = width; buf += linesize; ptr = buf; } } if(left<=GIF_CHUNKS) { put_bits(&p, 9, 0x101); /* end of stream */ flush_put_bits(&p); } if(put_bits_ptr(&p) - p.buf > 0) { bytestream_put_byte(bytestream, put_bits_ptr(&p) - p.buf); /* byte count of the packet */ bytestream_put_buffer(bytestream, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */ p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */ } left-=GIF_CHUNKS; } bytestream_put_byte(bytestream, 0x00); /* end of image block */ bytestream_put_byte(bytestream, 0x3b); return 0; } typedef struct { AVFrame picture; } GIFContext; static av_cold int gif_encode_init(AVCodecContext *avctx) { GIFContext *s = avctx->priv_data; avctx->coded_frame = &s->picture; return 0; } /* better than nothing gif encoder */ static int gif_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int buf_size, void *data) { GIFContext *s = avctx->priv_data; AVFrame *pict = data; AVFrame *const p = (AVFrame *)&s->picture; uint8_t *outbuf_ptr = outbuf; *p = *pict; p->pict_type = FF_I_TYPE; p->key_frame = 1; gif_image_write_header(&outbuf_ptr, avctx->width, avctx->height, (uint32_t *)pict->data[1]); gif_image_write_image(&outbuf_ptr, 0, 0, avctx->width, avctx->height, pict->data[0], pict->linesize[0], PIX_FMT_PAL8); return outbuf_ptr - outbuf; } AVCodec gif_encoder = { "gif", CODEC_TYPE_VIDEO, CODEC_ID_GIF, sizeof(GIFContext), gif_encode_init, gif_encode_frame, NULL, //encode_end, .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}, .long_name= NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"), };