3 * Copyright (c) 2000 Fabrice Bellard.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * First version by Francois Revol revol@free.fr
23 * Features and limitations:
24 * - currently no compression is performed,
25 * in fact the size of the data is 9/8 the size of the image in 8bpp
26 * - uses only a global standard palette
27 * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
29 * Reference documents:
30 * http://www.goice.co.jp/member/mo/formats/gif.html
31 * http://astronomy.swin.edu.au/pbourke/dataformats/gif/
32 * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
34 * this url claims to have an LZW algorithm not covered by Unisys patent:
35 * http://www.msg.net/utility/whirlgif/gifencod.html
36 * could help reduce the size of the files _a lot_...
37 * some sites mentions an RLE type compression also.
41 #include "bitstream.h"
43 /* bitstream minipacket size */
44 #define GIF_CHUNKS 100
46 /* slows down the decoding (and some browsers doesn't like it) */
47 /* #define GIF_ADD_APP_HEADER */
55 /* we use the standard 216 color palette */
57 /* this script was used to create the palette:
58 * 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
59 * echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
62 static const rgb_triplet gif_clut[216] = {
63 { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
64 { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
65 { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
66 { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
67 { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
68 { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
69 { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
70 { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
71 { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
72 { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
73 { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
74 { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
75 { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
76 { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
77 { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
78 { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
79 { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
80 { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
81 { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
82 { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
83 { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
84 { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
85 { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
86 { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
87 { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
88 { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
89 { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
90 { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
91 { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
92 { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
93 { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
94 { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
95 { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
96 { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
97 { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
98 { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
101 /* The GIF format uses reversed order for bitstreams... */
102 /* at least they don't use PDP_ENDIAN :) */
103 /* so we 'extend' PutBitContext. hmmm, OOP :) */
104 /* seems this thing changed slightly since I wrote it... */
106 #ifdef ALT_BITSTREAM_WRITER
107 # error no ALT_BITSTREAM_WRITER support for now
110 static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
112 unsigned int bit_buf;
116 st_out_bit_counts[st_current_index] += n;
118 // printf("put_bits=%d %x\n", n, value);
119 assert(n == 32 || value < (1U << n));
121 bit_buf = s->bit_buf;
122 bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
124 // printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
126 if (n < (32-bit_cnt)) {
127 bit_buf |= value << (bit_cnt);
130 bit_buf |= value << (bit_cnt);
132 *s->buf_ptr = bit_buf & 0xff;
133 s->buf_ptr[1] = (bit_buf >> 8) & 0xff;
134 s->buf_ptr[2] = (bit_buf >> 16) & 0xff;
135 s->buf_ptr[3] = (bit_buf >> 24) & 0xff;
137 //printf("bitbuf = %08x\n", bit_buf);
139 if (s->buf_ptr >= s->buf_end)
140 puts("bit buffer overflow !!"); // should never happen ! who got rid of the callback ???
141 // flush_buffer_rev(s);
142 bit_cnt=bit_cnt + n - 32;
146 bit_buf = value >> (n - bit_cnt);
150 s->bit_buf = bit_buf;
151 s->bit_left = 32 - bit_cnt;
154 /* pad the end of the output stream with zeros */
155 static void gif_flush_put_bits_rev(PutBitContext *s)
157 while (s->bit_left < 32) {
158 /* XXX: should test end of buffer */
159 *s->buf_ptr++=s->bit_buf & 0xff;
163 // flush_buffer_rev(s);
168 /* !RevPutBitContext */
171 static int gif_image_write_header(ByteIOContext *pb,
172 int width, int height, uint32_t *palette)
180 put_le16(pb, height);
182 put_byte(pb, 0xf7); /* flags: global clut, 256 entries */
183 put_byte(pb, 0x1f); /* background color index */
184 put_byte(pb, 0); /* aspect ratio */
186 /* the global palette */
188 put_buffer(pb, (unsigned char *)gif_clut, 216*3);
189 for(i=0;i<((256-216)*3);i++)
194 put_byte(pb, (v >> 16) & 0xff);
195 put_byte(pb, (v >> 8) & 0xff);
196 put_byte(pb, (v) & 0xff);
200 /* application extension header */
201 /* XXX: not really sure what to put in here... */
202 #ifdef GIF_ADD_APP_HEADER
206 put_tag(pb, "NETSCAPE2.0");
215 /* this is maybe slow, but allows for extensions */
216 static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
218 return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
222 static int gif_image_write_image(ByteIOContext *pb,
223 int x1, int y1, int width, int height,
224 const uint8_t *buf, int linesize, int pix_fmt)
227 uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
236 put_le16(pb, height);
237 put_byte(pb, 0x00); /* flags */
242 left= width * height;
244 init_put_bits(&p, buffer, 130);
247 * the thing here is the bitstream is written as little packets, with a size byte before
248 * but it's still the same bitstream between packets (no flush !)
254 gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
256 for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
257 if (pix_fmt == PIX_FMT_RGB24) {
258 v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
263 gif_put_bits_rev(&p, 9, v);
271 if(left<=GIF_CHUNKS) {
272 gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
273 gif_flush_put_bits_rev(&p);
275 if(pbBufPtr(&p) - p.buf > 0) {
276 put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
277 put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
278 p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
282 put_byte(pb, 0x00); /* end of image block */
288 int64_t time, file_time;
289 uint8_t buffer[100]; /* data chunks */
292 static int gif_write_header(AVFormatContext *s)
294 GIFContext *gif = s->priv_data;
295 ByteIOContext *pb = &s->pb;
296 AVCodecContext *enc, *video_enc;
297 int i, width, height/*, rate*/;
299 /* XXX: do we reject audio streams or just ignore them ?
300 if(s->nb_streams > 1)
307 for(i=0;i<s->nb_streams;i++) {
308 enc = &s->streams[i]->codec;
309 if (enc->codec_type != CODEC_TYPE_AUDIO)
317 width = video_enc->width;
318 height = video_enc->height;
319 // rate = video_enc->frame_rate;
322 /* XXX: is it allowed ? seems to work so far... */
323 video_enc->pix_fmt = PIX_FMT_RGB24;
325 gif_image_write_header(pb, width, height, NULL);
327 put_flush_packet(&s->pb);
331 static int gif_write_video(AVFormatContext *s,
332 AVCodecContext *enc, const uint8_t *buf, int size)
334 ByteIOContext *pb = &s->pb;
335 GIFContext *gif = s->priv_data;
339 /* graphic control extension block */
342 put_byte(pb, 0x04); /* block size */
343 put_byte(pb, 0x04); /* flags */
345 /* 1 jiffy is 1/70 s */
346 /* the delay_time field indicates the number of jiffies - 1 */
347 delay = gif->file_time - gif->time;
349 /* XXX: should use delay, in order to be more accurate */
350 /* instead of using the same rounded value each time */
351 /* XXX: don't even remember if I really use it for now */
352 jiffies = (70*enc->frame_rate_base/enc->frame_rate) - 1;
354 put_le16(pb, jiffies);
356 put_byte(pb, 0x1f); /* transparent color index */
359 gif_image_write_image(pb, 0, 0, enc->width, enc->height,
360 buf, enc->width * 3, PIX_FMT_RGB24);
362 put_flush_packet(&s->pb);
366 static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
368 AVCodecContext *codec = &s->streams[pkt->stream_index]->codec;
369 if (codec->codec_type == CODEC_TYPE_AUDIO)
370 return 0; /* just ignore audio */
372 return gif_write_video(s, codec, pkt->data, pkt->size);
375 static int gif_write_trailer(AVFormatContext *s)
377 ByteIOContext *pb = &s->pb;
380 put_flush_packet(&s->pb);
384 /* better than nothing gif image writer */
385 int gif_write(ByteIOContext *pb, AVImageInfo *info)
387 gif_image_write_header(pb, info->width, info->height,
388 (uint32_t *)info->pict.data[1]);
389 gif_image_write_image(pb, 0, 0, info->width, info->height,
390 info->pict.data[0], info->pict.linesize[0],
393 put_flush_packet(pb);
397 static AVOutputFormat gif_oformat = {
410 extern AVInputFormat gif_iformat;
414 av_register_output_format(&gif_oformat);
415 av_register_input_format(&gif_iformat);