3 * Copyright (c) 2000 Fabrice Bellard
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 * First version by Francois Revol revol@free.fr
25 * Features and limitations:
26 * - currently no compression is performed,
27 * in fact the size of the data is 9/8 the size of the image in 8bpp
28 * - uses only a global standard palette
29 * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
31 * Reference documents:
32 * http://www.goice.co.jp/member/mo/formats/gif.html
33 * http://astronomy.swin.edu.au/pbourke/dataformats/gif/
34 * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
36 * this url claims to have an LZW algorithm not covered by Unisys patent:
37 * http://www.msg.net/utility/whirlgif/gifencod.html
38 * could help reduce the size of the files _a lot_...
39 * some sites mentions an RLE type compression also.
43 #include "libavutil/log.h"
44 #include "libavutil/opt.h"
46 /* The GIF format uses reversed order for bitstreams... */
47 /* at least they don't use PDP_ENDIAN :) */
48 #define BITSTREAM_WRITER_LE
50 #include "libavcodec/put_bits.h"
52 /* bitstream minipacket size */
53 #define GIF_CHUNKS 100
55 /* slows down the decoding (and some browsers don't like it) */
56 /* update on the 'some browsers don't like it issue from above:
57 * this was probably due to missing 'Data Sub-block Terminator'
58 * (byte 19) in the app_header */
59 #define GIF_ADD_APP_HEADER // required to enable looping of animated gif
67 /* we use the standard 216 color palette */
69 /* this script was used to create the palette:
70 * for r in 00 33 66 99 cc ff; do
71 * for g in 00 33 66 99 cc ff; do
73 * for b in 00 33 66 99 cc ff; do
74 * echo -n "{ 0x$r, 0x$g, 0x$b }, "
81 static const rgb_triplet gif_clut[216] = {
82 { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
83 { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
84 { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
85 { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
86 { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
87 { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
88 { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
89 { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
90 { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
91 { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
92 { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
93 { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
94 { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
95 { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
96 { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
97 { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
98 { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
99 { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
100 { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
101 { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
102 { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
103 { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
104 { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
105 { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
106 { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
107 { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
108 { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
109 { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
110 { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
111 { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
112 { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
113 { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
114 { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
115 { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
116 { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
117 { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
121 static int gif_image_write_header(AVIOContext *pb, int width, int height,
122 int loop_count, uint32_t *palette)
127 avio_write(pb, "GIF", 3);
128 avio_write(pb, "89a", 3);
129 avio_wl16(pb, width);
130 avio_wl16(pb, height);
132 avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
133 avio_w8(pb, 0x1f); /* background color index */
134 avio_w8(pb, 0); /* aspect ratio */
136 /* the global palette */
138 avio_write(pb, (const unsigned char *)gif_clut, 216 * 3);
139 for (i = 0; i < ((256 - 216) * 3); i++)
142 for (i = 0; i < 256; i++) {
144 avio_w8(pb, (v >> 16) & 0xff);
145 avio_w8(pb, (v >> 8) & 0xff);
146 avio_w8(pb, (v) & 0xff);
150 /* update: this is the 'NETSCAPE EXTENSION' that allows for looped animated
151 * GIF, see http://members.aol.com/royalef/gifabout.htm#net-extension
153 * byte 1 : 33 (hex 0x21) GIF Extension code
154 * byte 2 : 255 (hex 0xFF) Application Extension Label
155 * byte 3 : 11 (hex (0x0B) Length of Application Block
156 * (eleven bytes of data to follow)
157 * bytes 4 to 11 : "NETSCAPE"
158 * bytes 12 to 14 : "2.0"
159 * byte 15 : 3 (hex 0x03) Length of Data Sub-Block
160 * (three bytes of data to follow)
161 * byte 16 : 1 (hex 0x01)
162 * bytes 17 to 18 : 0 to 65535, an unsigned integer in
163 * lo-hi byte format. This indicate the
164 * number of iterations the loop should
166 * bytes 19 : 0 (hex 0x00) a Data Sub-block Terminator
169 /* application extension header */
170 #ifdef GIF_ADD_APP_HEADER
171 if (loop_count >= 0 && loop_count <= 65535) {
176 avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);
177 avio_w8(pb, 0x03); // byte 15
178 avio_w8(pb, 0x01); // byte 16
179 avio_wl16(pb, (uint16_t)loop_count);
180 avio_w8(pb, 0x00); // byte 19
186 /* this is maybe slow, but allows for extensions */
187 static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
189 return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6);
192 static int gif_image_write_image(AVIOContext *pb,
193 int x1, int y1, int width, int height,
194 const uint8_t *buf, int linesize, int pix_fmt)
197 uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
205 avio_wl16(pb, width);
206 avio_wl16(pb, height);
207 avio_w8(pb, 0x00); /* flags */
212 left = width * height;
214 init_put_bits(&p, buffer, 130);
217 * the thing here is the bitstream is written as little packets, with a size
218 * byte before but it's still the same bitstream between packets (no flush !)
223 put_bits(&p, 9, 0x0100); /* clear code */
225 for (i = (left < GIF_CHUNKS) ? left : GIF_CHUNKS; i; i--) {
226 if (pix_fmt == AV_PIX_FMT_RGB24) {
227 v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
240 if (left <= GIF_CHUNKS) {
241 put_bits(&p, 9, 0x101); /* end of stream */
244 if (put_bits_ptr(&p) - p.buf > 0) {
245 avio_w8(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
246 avio_write(pb, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */
247 p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
251 avio_w8(pb, 0x00); /* end of image block */
257 AVClass *class; /** Class for private options. */
258 int64_t time, file_time;
259 uint8_t buffer[100]; /* data chunks */
263 static int gif_write_header(AVFormatContext *s)
265 GIFContext *gif = s->priv_data;
266 AVIOContext *pb = s->pb;
267 AVCodecContext *enc, *video_enc;
268 int i, width, height /*, rate*/;
270 /* XXX: do we reject audio streams or just ignore them ?
271 * if (s->nb_streams > 1)
278 for (i = 0; i < s->nb_streams; i++) {
279 enc = s->streams[i]->codec;
280 if (enc->codec_type != AVMEDIA_TYPE_AUDIO)
288 width = video_enc->width;
289 height = video_enc->height;
290 // rate = video_enc->time_base.den;
293 if (video_enc->pix_fmt != AV_PIX_FMT_RGB24) {
294 av_log(s, AV_LOG_ERROR,
295 "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");
299 gif_image_write_header(pb, width, height, gif->loop, NULL);
305 static int gif_write_video(AVFormatContext *s, AVCodecContext *enc,
306 const uint8_t *buf, int size)
308 AVIOContext *pb = s->pb;
311 /* graphic control extension block */
314 avio_w8(pb, 0x04); /* block size */
315 avio_w8(pb, 0x04); /* flags */
317 /* 1 jiffy is 1/70 s */
318 /* the delay_time field indicates the number of jiffies - 1 */
319 /* XXX: should use delay, in order to be more accurate */
320 /* instead of using the same rounded value each time */
321 /* XXX: don't even remember if I really use it for now */
322 jiffies = (70 * enc->time_base.num / enc->time_base.den) - 1;
324 avio_wl16(pb, jiffies);
326 avio_w8(pb, 0x1f); /* transparent color index */
329 gif_image_write_image(pb, 0, 0, enc->width, enc->height,
330 buf, enc->width * 3, AV_PIX_FMT_RGB24);
336 static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
338 AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
339 if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
340 return 0; /* just ignore audio */
342 return gif_write_video(s, codec, pkt->data, pkt->size);
345 static int gif_write_trailer(AVFormatContext *s)
347 AVIOContext *pb = s->pb;
354 #define OFFSET(x) offsetof(GIFContext, x)
355 #define ENC AV_OPT_FLAG_ENCODING_PARAM
356 static const AVOption options[] = {
357 { "loop", "Number of times to loop the output.", OFFSET(loop),
358 AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 65535, ENC },
362 static const AVClass gif_muxer_class = {
363 .class_name = "GIF muxer",
364 .item_name = av_default_item_name,
365 .version = LIBAVUTIL_VERSION_INT,
369 AVOutputFormat ff_gif_muxer = {
371 .long_name = NULL_IF_CONFIG_SMALL("GIF Animation"),
372 .mime_type = "image/gif",
374 .priv_data_size = sizeof(GIFContext),
375 .audio_codec = AV_CODEC_ID_NONE,
376 .video_codec = AV_CODEC_ID_RAWVIDEO,
377 .write_header = gif_write_header,
378 .write_packet = gif_write_packet,
379 .write_trailer = gif_write_trailer,
380 .priv_class = &gif_muxer_class,