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
44/* The GIF format uses reversed order for bitstreams... */
45/* at least they don't use PDP_ENDIAN :) */
46#define BITSTREAM_WRITER_LE
47
48#include "libavcodec/bitstream.h"
49
50/* bitstream minipacket size */
51#define GIF_CHUNKS 100
52
53/* slows down the decoding (and some browsers don't like it) */
54/* 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 */
55#define GIF_ADD_APP_HEADER // required to enable looping of animated gif
56
57typedef struct {
58    unsigned char r;
59    unsigned char g;
60    unsigned char b;
61} rgb_triplet;
62
63/* we use the standard 216 color palette */
64
65/* this script was used to create the palette:
66 * 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
67 *   echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
68 */
69
70static const rgb_triplet gif_clut[216] = {
71    { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
72    { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
73    { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
74    { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
75    { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
76    { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
77    { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
78    { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
79    { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
80    { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
81    { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
82    { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
83    { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
84    { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
85    { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
86    { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
87    { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
88    { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
89    { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
90    { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
91    { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
92    { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
93    { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
94    { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
95    { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
96    { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
97    { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
98    { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
99    { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
100    { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
101    { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
102    { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
103    { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
104    { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
105    { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
106    { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
107};
108
109/* GIF header */
110static int gif_image_write_header(ByteIOContext *pb,
111                                  int width, int height, int loop_count,
112                                  uint32_t *palette)
113{
114    int i;
115    unsigned int v;
116
117    put_tag(pb, "GIF");
118    put_tag(pb, "89a");
119    put_le16(pb, width);
120    put_le16(pb, height);
121
122    put_byte(pb, 0xf7); /* flags: global clut, 256 entries */
123    put_byte(pb, 0x1f); /* background color index */
124    put_byte(pb, 0); /* aspect ratio */
125
126    /* the global palette */
127    if (!palette) {
128        put_buffer(pb, (const unsigned char *)gif_clut, 216*3);
129        for(i=0;i<((256-216)*3);i++)
130            put_byte(pb, 0);
131    } else {
132        for(i=0;i<256;i++) {
133            v = palette[i];
134            put_byte(pb, (v >> 16) & 0xff);
135            put_byte(pb, (v >> 8) & 0xff);
136            put_byte(pb, (v) & 0xff);
137        }
138    }
139
140        /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
141                see http://members.aol.com/royalef/gifabout.htm#net-extension
142
143                byte   1       : 33 (hex 0x21) GIF Extension code
144                byte   2       : 255 (hex 0xFF) Application Extension Label
145                byte   3       : 11 (hex (0x0B) Length of Application Block
146                                         (eleven bytes of data to follow)
147                bytes  4 to 11 : "NETSCAPE"
148                bytes 12 to 14 : "2.0"
149                byte  15       : 3 (hex 0x03) Length of Data Sub-Block
150                                         (three bytes of data to follow)
151                byte  16       : 1 (hex 0x01)
152                bytes 17 to 18 : 0 to 65535, an unsigned integer in
153                                         lo-hi byte format. This indicate the
154                                         number of iterations the loop should
155                                         be executed.
156                bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
157        */
158
159    /* application extension header */
160#ifdef GIF_ADD_APP_HEADER
161    if (loop_count >= 0 && loop_count <= 65535) {
162    put_byte(pb, 0x21);
163    put_byte(pb, 0xff);
164    put_byte(pb, 0x0b);
165        put_tag(pb, "NETSCAPE2.0");  // bytes 4 to 14
166        put_byte(pb, 0x03); // byte 15
167        put_byte(pb, 0x01); // byte 16
168        put_le16(pb, (uint16_t)loop_count);
169        put_byte(pb, 0x00); // byte 19
170    }
171#endif
172    return 0;
173}
174
175/* this is maybe slow, but allows for extensions */
176static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
177{
178    return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6);
179}
180
181
182static int gif_image_write_image(ByteIOContext *pb,
183                                 int x1, int y1, int width, int height,
184                                 const uint8_t *buf, int linesize, int pix_fmt)
185{
186    PutBitContext p;
187    uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
188    int i, left, w, v;
189    const uint8_t *ptr;
190    /* image block */
191
192    put_byte(pb, 0x2c);
193    put_le16(pb, x1);
194    put_le16(pb, y1);
195    put_le16(pb, width);
196    put_le16(pb, height);
197    put_byte(pb, 0x00); /* flags */
198    /* no local clut */
199
200    put_byte(pb, 0x08);
201
202    left= width * height;
203
204    init_put_bits(&p, buffer, 130);
205
206/*
207 * the thing here is the bitstream is written as little packets, with a size byte before
208 * but it's still the same bitstream between packets (no flush !)
209 */
210    ptr = buf;
211    w = width;
212    while(left>0) {
213
214        put_bits(&p, 9, 0x0100); /* clear code */
215
216        for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
217            if (pix_fmt == PIX_FMT_RGB24) {
218                v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
219                ptr+=3;
220            } else {
221                v = *ptr++;
222            }
223            put_bits(&p, 9, v);
224            if (--w == 0) {
225                w = width;
226                buf += linesize;
227                ptr = buf;
228            }
229        }
230
231        if(left<=GIF_CHUNKS) {
232            put_bits(&p, 9, 0x101); /* end of stream */
233            flush_put_bits(&p);
234        }
235        if(pbBufPtr(&p) - p.buf > 0) {
236            put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
237            put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
238            p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
239        }
240        left-=GIF_CHUNKS;
241    }
242    put_byte(pb, 0x00); /* end of image block */
243
244    return 0;
245}
246
247typedef struct {
248    int64_t time, file_time;
249    uint8_t buffer[100]; /* data chunks */
250} GIFContext;
251
252static int gif_write_header(AVFormatContext *s)
253{
254    GIFContext *gif = s->priv_data;
255    ByteIOContext *pb = s->pb;
256    AVCodecContext *enc, *video_enc;
257    int i, width, height, loop_count /*, rate*/;
258
259/* XXX: do we reject audio streams or just ignore them ?
260    if(s->nb_streams > 1)
261        return -1;
262*/
263    gif->time = 0;
264    gif->file_time = 0;
265
266    video_enc = NULL;
267    for(i=0;i<s->nb_streams;i++) {
268        enc = s->streams[i]->codec;
269        if (enc->codec_type != CODEC_TYPE_AUDIO)
270            video_enc = enc;
271    }
272
273    if (!video_enc) {
274        av_free(gif);
275        return -1;
276    } else {
277        width = video_enc->width;
278        height = video_enc->height;
279        loop_count = s->loop_output;
280//        rate = video_enc->time_base.den;
281    }
282
283    if (video_enc->pix_fmt != PIX_FMT_RGB24) {
284        av_log(s, AV_LOG_ERROR, "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n");
285        return AVERROR(EIO);
286    }
287
288    gif_image_write_header(pb, width, height, loop_count, NULL);
289
290    put_flush_packet(s->pb);
291    return 0;
292}
293
294static int gif_write_video(AVFormatContext *s,
295                           AVCodecContext *enc, const uint8_t *buf, int size)
296{
297    ByteIOContext *pb = s->pb;
298    GIFContext *gif = s->priv_data;
299    int jiffies;
300    int64_t delay;
301
302    /* graphic control extension block */
303    put_byte(pb, 0x21);
304    put_byte(pb, 0xf9);
305    put_byte(pb, 0x04); /* block size */
306    put_byte(pb, 0x04); /* flags */
307
308    /* 1 jiffy is 1/70 s */
309    /* the delay_time field indicates the number of jiffies - 1 */
310    delay = gif->file_time - gif->time;
311
312    /* XXX: should use delay, in order to be more accurate */
313    /* instead of using the same rounded value each time */
314    /* XXX: don't even remember if I really use it for now */
315    jiffies = (70*enc->time_base.num/enc->time_base.den) - 1;
316
317    put_le16(pb, jiffies);
318
319    put_byte(pb, 0x1f); /* transparent color index */
320    put_byte(pb, 0x00);
321
322    gif_image_write_image(pb, 0, 0, enc->width, enc->height,
323                          buf, enc->width * 3, PIX_FMT_RGB24);
324
325    put_flush_packet(s->pb);
326    return 0;
327}
328
329static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
330{
331    AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
332    if (codec->codec_type == CODEC_TYPE_AUDIO)
333        return 0; /* just ignore audio */
334    else
335        return gif_write_video(s, codec, pkt->data, pkt->size);
336}
337
338static int gif_write_trailer(AVFormatContext *s)
339{
340    ByteIOContext *pb = s->pb;
341
342    put_byte(pb, 0x3b);
343    put_flush_packet(s->pb);
344    return 0;
345}
346
347AVOutputFormat gif_muxer = {
348    "gif",
349    NULL_IF_CONFIG_SMALL("GIF Animation"),
350    "image/gif",
351    "gif",
352    sizeof(GIFContext),
353    CODEC_ID_NONE,
354    CODEC_ID_RAWVIDEO,
355    gif_write_header,
356    gif_write_packet,
357    gif_write_trailer,
358};
359