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gif.c
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1 /*
2  * Animated GIF muxer
3  * Copyright (c) 2000 Fabrice Bellard
4  *
5  * This file is part of FFmpeg.
6  *
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.
11  *
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.
16  *
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
20  */
21 
22 /*
23  * First version by Francois Revol revol@free.fr
24  *
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).
30  *
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
35  *
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.
40  */
41 
42 #include "avformat.h"
43 #include "libavutil/log.h"
44 #include "libavutil/opt.h"
45 
46 /* The GIF format uses reversed order for bitstreams... */
47 /* at least they don't use PDP_ENDIAN :) */
48 #define BITSTREAM_WRITER_LE
49 
50 #include "libavcodec/put_bits.h"
51 
52 /* bitstream minipacket size */
53 #define GIF_CHUNKS 100
54 
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
60 
61 typedef struct {
62  unsigned char r;
63  unsigned char g;
64  unsigned char b;
65 } rgb_triplet;
66 
67 /* we use the standard 216 color palette */
68 
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
72  * echo -n " "
73  * for b in 00 33 66 99 cc ff; do
74  * echo -n "{ 0x$r, 0x$g, 0x$b }, "
75  * done
76  * echo ""
77  * done
78  * done
79  */
80 
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 },
118 };
119 
120 /* GIF header */
122  int loop_count, uint32_t *palette)
123 {
124  int i;
125  unsigned int v;
126 
127  avio_write(pb, "GIF", 3);
128  avio_write(pb, "89a", 3);
129  avio_wl16(pb, width);
130  avio_wl16(pb, height);
131 
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 */
135 
136  /* the global palette */
137  if (!palette) {
138  avio_write(pb, (const unsigned char *)gif_clut, 216 * 3);
139  for (i = 0; i < ((256 - 216) * 3); i++)
140  avio_w8(pb, 0);
141  } else {
142  for (i = 0; i < 256; i++) {
143  v = palette[i];
144  avio_w8(pb, (v >> 16) & 0xff);
145  avio_w8(pb, (v >> 8) & 0xff);
146  avio_w8(pb, (v) & 0xff);
147  }
148  }
149 
150  /* update: this is the 'NETSCAPE EXTENSION' that allows for looped animated
151  * GIF, see http://members.aol.com/royalef/gifabout.htm#net-extension
152  *
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
165  * be executed.
166  * bytes 19 : 0 (hex 0x00) a Data Sub-block Terminator
167  */
168 
169  /* application extension header */
170 #ifdef GIF_ADD_APP_HEADER
171  if (loop_count >= 0 && loop_count <= 65535) {
172  avio_w8(pb, 0x21);
173  avio_w8(pb, 0xff);
174  avio_w8(pb, 0x0b);
175  // bytes 4 to 14
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
181  }
182 #endif
183  return 0;
184 }
185 
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)
188 {
189  return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6);
190 }
191 
193  int x1, int y1, int width, int height,
194  const uint8_t *buf, int linesize, int pix_fmt)
195 {
196  PutBitContext p;
197  uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
198  int i, left, w, v;
199  const uint8_t *ptr;
200  /* image block */
201 
202  avio_w8(pb, 0x2c);
203  avio_wl16(pb, x1);
204  avio_wl16(pb, y1);
205  avio_wl16(pb, width);
206  avio_wl16(pb, height);
207  avio_w8(pb, 0x00); /* flags */
208  /* no local clut */
209 
210  avio_w8(pb, 0x08);
211 
212  left = width * height;
213 
214  init_put_bits(&p, buffer, 130);
215 
216 /*
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 !)
219  */
220  ptr = buf;
221  w = width;
222  while (left > 0) {
223  put_bits(&p, 9, 0x0100); /* clear code */
224 
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]);
228  ptr += 3;
229  } else {
230  v = *ptr++;
231  }
232  put_bits(&p, 9, v);
233  if (--w == 0) {
234  w = width;
235  buf += linesize;
236  ptr = buf;
237  }
238  }
239 
240  if (left <= GIF_CHUNKS) {
241  put_bits(&p, 9, 0x101); /* end of stream */
242  flush_put_bits(&p);
243  }
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 */
248  }
249  left -= GIF_CHUNKS;
250  }
251  avio_w8(pb, 0x00); /* end of image block */
252 
253  return 0;
254 }
255 
256 typedef struct {
257  AVClass *class; /** Class for private options. */
258  int64_t time, file_time;
259  uint8_t buffer[100]; /* data chunks */
260  int loop;
261 } GIFContext;
262 
264 {
265  GIFContext *gif = s->priv_data;
266  AVIOContext *pb = s->pb;
267  AVCodecContext *enc, *video_enc;
268  int i, width, height /*, rate*/;
269 
270 /* XXX: do we reject audio streams or just ignore them ?
271  * if (s->nb_streams > 1)
272  * return -1;
273  */
274  gif->time = 0;
275  gif->file_time = 0;
276 
277  video_enc = NULL;
278  for (i = 0; i < s->nb_streams; i++) {
279  enc = s->streams[i]->codec;
280  if (enc->codec_type != AVMEDIA_TYPE_AUDIO)
281  video_enc = enc;
282  }
283 
284  if (!video_enc) {
285  av_free(gif);
286  return -1;
287  } else {
288  width = video_enc->width;
289  height = video_enc->height;
290 // rate = video_enc->time_base.den;
291  }
292 
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");
296  return AVERROR(EIO);
297  }
298 
299  gif_image_write_header(pb, width, height, gif->loop, NULL);
300 
301  avio_flush(s->pb);
302  return 0;
303 }
304 
306  const uint8_t *buf, int size)
307 {
308  AVIOContext *pb = s->pb;
309  int jiffies;
310 
311  /* graphic control extension block */
312  avio_w8(pb, 0x21);
313  avio_w8(pb, 0xf9);
314  avio_w8(pb, 0x04); /* block size */
315  avio_w8(pb, 0x04); /* flags */
316 
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;
323 
324  avio_wl16(pb, jiffies);
325 
326  avio_w8(pb, 0x1f); /* transparent color index */
327  avio_w8(pb, 0x00);
328 
329  gif_image_write_image(pb, 0, 0, enc->width, enc->height,
330  buf, enc->width * 3, AV_PIX_FMT_RGB24);
331 
332  avio_flush(s->pb);
333  return 0;
334 }
335 
337 {
338  AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
339  if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
340  return 0; /* just ignore audio */
341  else
342  return gif_write_video(s, codec, pkt->data, pkt->size);
343 }
344 
346 {
347  AVIOContext *pb = s->pb;
348 
349  avio_w8(pb, 0x3b);
350 
351  return 0;
352 }
353 
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 },
359  { NULL },
360 };
361 
362 static const AVClass gif_muxer_class = {
363  .class_name = "GIF muxer",
364  .item_name = av_default_item_name,
365  .version = LIBAVUTIL_VERSION_INT,
366  .option = options,
367 };
368 
370  .name = "gif",
371  .long_name = NULL_IF_CONFIG_SMALL("GIF Animation"),
372  .mime_type = "image/gif",
373  .extensions = "gif",
374  .priv_data_size = sizeof(GIFContext),
375  .audio_codec = AV_CODEC_ID_NONE,
376  .video_codec = AV_CODEC_ID_RAWVIDEO,
380  .priv_class = &gif_muxer_class,
381 };