3 * Copyright (c) 2000 Fabrice Bellard
4 * Copyright (c) 2002 Francois Revol
5 * Copyright (c) 2006 Baptiste Coudurier
7 * first version by Francois Revol <revol@free.fr>
9 * This file is part of Libav.
11 * Libav is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
16 * Libav is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with Libav; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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).
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
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.
45 #include "bytestream.h"
49 /* The GIF format uses reversed order for bitstreams... */
50 /* at least they don't use PDP_ENDIAN :) */
51 #define BITSTREAM_WRITER_LE
62 static int gif_image_write_header(AVCodecContext *avctx,
63 uint8_t **bytestream, uint32_t *palette)
68 bytestream_put_buffer(bytestream, "GIF", 3);
69 bytestream_put_buffer(bytestream, "89a", 3);
70 bytestream_put_le16(bytestream, avctx->width);
71 bytestream_put_le16(bytestream, avctx->height);
73 bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
74 bytestream_put_byte(bytestream, 0x1f); /* background color index */
75 bytestream_put_byte(bytestream, 0); /* aspect ratio */
77 /* the global palette */
80 bytestream_put_be24(bytestream, v);
86 static int gif_image_write_image(AVCodecContext *avctx,
87 uint8_t **bytestream, uint8_t *end,
88 const uint8_t *buf, int linesize)
90 GIFContext *s = avctx->priv_data;
95 bytestream_put_byte(bytestream, 0x2c);
96 bytestream_put_le16(bytestream, 0);
97 bytestream_put_le16(bytestream, 0);
98 bytestream_put_le16(bytestream, avctx->width);
99 bytestream_put_le16(bytestream, avctx->height);
100 bytestream_put_byte(bytestream, 0x00); /* flags */
103 bytestream_put_byte(bytestream, 0x08);
105 ff_lzw_encode_init(s->lzw, s->buf, avctx->width*avctx->height,
106 12, FF_LZW_GIF, put_bits);
109 for (height = avctx->height; height--;) {
110 len += ff_lzw_encode(s->lzw, ptr, avctx->width);
113 len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
117 int size = FFMIN(255, len);
118 bytestream_put_byte(bytestream, size);
119 if (end - *bytestream < size)
121 bytestream_put_buffer(bytestream, ptr, size);
125 bytestream_put_byte(bytestream, 0x00); /* end of image block */
126 bytestream_put_byte(bytestream, 0x3b);
130 static av_cold int gif_encode_init(AVCodecContext *avctx)
132 GIFContext *s = avctx->priv_data;
134 avctx->coded_frame = &s->picture;
135 s->lzw = av_mallocz(ff_lzw_encode_state_size);
137 return AVERROR(ENOMEM);
138 s->buf = av_malloc(avctx->width*avctx->height*2);
140 return AVERROR(ENOMEM);
144 /* better than nothing gif encoder */
145 static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
146 const AVFrame *pict, int *got_packet)
148 GIFContext *s = avctx->priv_data;
149 AVFrame *const p = &s->picture;
150 uint8_t *outbuf_ptr, *end;
153 if ((ret = ff_alloc_packet(pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0) {
154 av_log(avctx, AV_LOG_ERROR, "Error getting output packet.\n");
157 outbuf_ptr = pkt->data;
158 end = pkt->data + pkt->size;
161 p->pict_type = AV_PICTURE_TYPE_I;
163 gif_image_write_header(avctx, &outbuf_ptr, (uint32_t *)pict->data[1]);
164 gif_image_write_image(avctx, &outbuf_ptr, end, pict->data[0], pict->linesize[0]);
166 pkt->size = outbuf_ptr - pkt->data;
167 pkt->flags |= AV_PKT_FLAG_KEY;
173 static int gif_encode_close(AVCodecContext *avctx)
175 GIFContext *s = avctx->priv_data;
182 AVCodec ff_gif_encoder = {
184 .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
185 .type = AVMEDIA_TYPE_VIDEO,
186 .id = AV_CODEC_ID_GIF,
187 .priv_data_size = sizeof(GIFContext),
188 .init = gif_encode_init,
189 .encode2 = gif_encode_frame,
190 .close = gif_encode_close,
191 .pix_fmts = (const enum AVPixelFormat[]){
192 AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
193 AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE