1/*
2 * Animated GIF muxer
3 * Copyright (c) 2000 Fabrice Bellard
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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: this was probably due to missing 'Data Sub-block Terminator' (byte 19) in the app_header */
57#define GIF_ADD_APP_HEADER // required to enable looping of animated gif
58
59typedef struct {
60    unsigned char r;
61    unsigned char g;
62    unsigned char b;
63} rgb_triplet;
64
65/* we use the standard 216 color palette */
66
67/* this script was used to create the palette:
68 * 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
69 *   echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
70 */
71
72static const rgb_triplet gif_clut[216] = {
73    { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
74    { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
75    { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
76    { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
77    { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
78    { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
79    { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
80    { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
81    { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
82    { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
83    { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
84    { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
85    { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
86    { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
87    { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
88    { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
89    { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
90    { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
91    { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
92    { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
93    { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
94    { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
95    { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
96    { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
97    { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
98    { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
99    { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
100    { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
101    { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
102    { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
103    { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
104    { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
105    { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
106    { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
107    { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
108    { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
109};
110
111/* GIF header */
112static int gif_image_write_header(AVIOContext *pb,
113                                  int width, int height, int loop_count,
114                                  uint32_t *palette)
115{
116    int i;
117    unsigned int v;
118
119    avio_write(pb, "GIF", 3);
120    avio_write(pb, "89a", 3);
121    avio_wl16(pb, width);
122    avio_wl16(pb, height);
123
124    avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
125    avio_w8(pb, 0x1f); /* background color index */
126    avio_w8(pb, 0);    /* aspect ratio */
127
128    /* the global palette */
129    if (!palette) {
130        avio_write(pb, (const unsigned char *)gif_clut, 216*3);
131        for(i=0;i<((256-216)*3);i++)
132            avio_w8(pb, 0);
133    } else {
134        for(i=0;i<256;i++) {
135            v = palette[i];
136            avio_w8(pb, (v >> 16) & 0xff);
137            avio_w8(pb, (v >> 8) & 0xff);
138            avio_w8(pb, (v) & 0xff);
139        }
140    }
141
142        /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
143                see http://members.aol.com/royalef/gifabout.htm#net-extension
144
145                byte   1       : 33 (hex 0x21) GIF Extension code
146                byte   2       : 255 (hex 0xFF) Application Extension Label
147                byte   3       : 11 (hex (0x0B) Length of Application Block
148                                         (eleven bytes of data to follow)
149                bytes  4 to 11 : "NETSCAPE"
150                bytes 12 to 14 : "2.0"
151                byte  15       : 3 (hex 0x03) Length of Data Sub-Block
152                                         (three bytes of data to follow)
153                byte  16       : 1 (hex 0x01)
154                bytes 17 to 18 : 0 to 65535, an unsigned integer in
155                                         lo-hi byte format. This indicate the
156                                         number of iterations the loop should
157                                         be executed.
158                bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
159        */
160
161    /* application extension header */
162#ifdef GIF_ADD_APP_HEADER
163    if (loop_count >= 0 && loop_count <= 65535) {
164    avio_w8(pb, 0x21);
165    avio_w8(pb, 0xff);
166    avio_w8(pb, 0x0b);
167        avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);  // bytes 4 to 14
168        avio_w8(pb, 0x03); // byte 15
169        avio_w8(pb, 0x01); // byte 16
170        avio_wl16(pb, (uint16_t)loop_count);
171        avio_w8(pb, 0x00); // byte 19
172    }
173#endif
174    return 0;
175}
176
177/* this is maybe slow, but allows for extensions */
178static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
179{
180    return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6);
181}
182
183
184static int gif_image_write_image(AVIOContext *pb,
185                                 int x1, int y1, int width, int height,
186                                 const uint8_t *buf, int linesize, int pix_fmt)
187{
188    PutBitContext p;
189    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
190    int i, left, w, v;
191    const uint8_t *ptr;
192    /* image block */
193
194    avio_w8(pb, 0x2c);
195    avio_wl16(pb, x1);
196    avio_wl16(pb, y1);
197    avio_wl16(pb, width);
198    avio_wl16(pb, height);
199    avio_w8(pb, 0x00); /* flags */
200    /* no local clut */
201
202    avio_w8(pb, 0x08);
203
204    left= width * height;
205
206    init_put_bits(&p, buffer, 130);
207
208/*
209 * the thing here is the bitstream is written as little packets, with a size byte before
210 * but it's still the same bitstream between packets (no flush !)
211 */
212    ptr = buf;
213    w = width;
214    while(left>0) {
215
216        put_bits(&p, 9, 0x0100); /* clear code */
217
218        for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
219            if (pix_fmt == PIX_FMT_RGB24) {
220                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
221                ptr+=3;
222            } else {
223                v = *ptr++;
224            }
225            put_bits(&p, 9, v);
226            if (--w == 0) {
227                w = width;
228                buf += linesize;
229                ptr = buf;
230            }
231        }
232
233        if(left<=GIF_CHUNKS) {
234            put_bits(&p, 9, 0x101); /* end of stream */
235            flush_put_bits(&p);
236        }
237        if(put_bits_ptr(&p) - p.buf > 0) {
238            avio_w8(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
239            avio_write(pb, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */
240            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
241        }
242        left-=GIF_CHUNKS;
243    }
244    avio_w8(pb, 0x00); /* end of image block */
245
246    return 0;
247}
248
249typedef struct {
250    AVClass *class;         /** Class for private options. */
251    int64_t time, file_time;
252    uint8_t buffer[100]; /* data chunks */
253    int loop;
254} GIFContext;
255
256static int gif_write_header(AVFormatContext *s)
257{
258    GIFContext *gif = s->priv_data;
259    AVIOContext *pb = s->pb;
260    AVCodecContext *enc, *video_enc;
261    int i, width, height /*, rate*/;
262
263/* XXX: do we reject audio streams or just ignore them ?
264    if(s->nb_streams > 1)
265        return -1;
266*/
267    gif->time = 0;
268    gif->file_time = 0;
269
270    video_enc = NULL;
271    for(i=0;i<s->nb_streams;i++) {
272        enc = s->streams[i]->codec;
273        if (enc->codec_type != AVMEDIA_TYPE_AUDIO)
274            video_enc = enc;
275    }
276
277    if (!video_enc) {
278        av_free(gif);
279        return -1;
280    } else {
281        width = video_enc->width;
282        height = video_enc->height;
283//        rate = video_enc->time_base.den;
284    }
285
286    if (video_enc->pix_fmt != PIX_FMT_RGB24) {
287        av_log(s, AV_LOG_ERROR, "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");
288        return AVERROR(EIO);
289    }
290
291#if FF_API_LOOP_OUTPUT
292    if (s->loop_output)
293        gif->loop = s->loop_output;
294#endif
295
296    gif_image_write_header(pb, width, height, gif->loop, NULL);
297
298    avio_flush(s->pb);
299    return 0;
300}
301
302static int gif_write_video(AVFormatContext *s,
303                           AVCodecContext *enc, const uint8_t *buf, int size)
304{
305    AVIOContext *pb = s->pb;
306    int jiffies;
307
308    /* graphic control extension block */
309    avio_w8(pb, 0x21);
310    avio_w8(pb, 0xf9);
311    avio_w8(pb, 0x04); /* block size */
312    avio_w8(pb, 0x04); /* flags */
313
314    /* 1 jiffy is 1/70 s */
315    /* the delay_time field indicates the number of jiffies - 1 */
316    /* XXX: should use delay, in order to be more accurate */
317    /* instead of using the same rounded value each time */
318    /* XXX: don't even remember if I really use it for now */
319    jiffies = (70*enc->time_base.num/enc->time_base.den) - 1;
320
321    avio_wl16(pb, jiffies);
322
323    avio_w8(pb, 0x1f); /* transparent color index */
324    avio_w8(pb, 0x00);
325
326    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
327                          buf, enc->width * 3, PIX_FMT_RGB24);
328
329    avio_flush(s->pb);
330    return 0;
331}
332
333static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
334{
335    AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
336    if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
337        return 0; /* just ignore audio */
338    else
339        return gif_write_video(s, codec, pkt->data, pkt->size);
340}
341
342static int gif_write_trailer(AVFormatContext *s)
343{
344    AVIOContext *pb = s->pb;
345
346    avio_w8(pb, 0x3b);
347    avio_flush(s->pb);
348    return 0;
349}
350
351#define OFFSET(x) offsetof(GIFContext, x)
352#define ENC AV_OPT_FLAG_ENCODING_PARAM
353static const AVOption options[] = {
354    { "loop", "Number of times to loop the output.", OFFSET(loop), AV_OPT_TYPE_INT, {0}, 0, 65535, ENC },
355    { NULL },
356};
357
358static const AVClass gif_muxer_class = {
359    .class_name = "GIF muxer",
360    .item_name  = av_default_item_name,
361    .version    = LIBAVUTIL_VERSION_INT,
362    .option     = options,
363};
364
365AVOutputFormat ff_gif_muxer = {
366    .name              = "gif",
367    .long_name         = NULL_IF_CONFIG_SMALL("GIF Animation"),
368    .mime_type         = "image/gif",
369    .extensions        = "gif",
370    .priv_data_size    = sizeof(GIFContext),
371    .audio_codec       = CODEC_ID_NONE,
372    .video_codec       = CODEC_ID_RAWVIDEO,
373    .write_header      = gif_write_header,
374    .write_packet      = gif_write_packet,
375    .write_trailer     = gif_write_trailer,
376    .priv_class = &gif_muxer_class,
377};
378