libavcodec/gif.c

   1 /*
   2  * GIF encoder.
   3  * Copyright (c) 2000 Fabrice Bellard.
   4  * Copyright (c) 2002 Francois Revol.
   5  * Copyright (c) 2006 Baptiste Coudurier.
   6  *
   7  * This file is part of FFmpeg.
   8  *
   9  * FFmpeg is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * FFmpeg is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with FFmpeg; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 /*
  25  * First version by Francois Revol revol@free.fr
  26  *
  27  * Features and limitations:
  28  * - currently no compression is performed,
  29  *   in fact the size of the data is 9/8 the size of the image in 8bpp
  30  * - uses only a global standard palette
  31  * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
  32  *
  33  * Reference documents:
  34  * http://www.goice.co.jp/member/mo/formats/gif.html
  35  * http://astronomy.swin.edu.au/pbourke/dataformats/gif/
  36  * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
  37  *
  38  * this url claims to have an LZW algorithm not covered by Unisys patent:
  39  * http://www.msg.net/utility/whirlgif/gifencod.html
  40  * could help reduce the size of the files _a lot_...
  41  * some sites mentions an RLE type compression also.
  42  */
  43
  44 #include "avcodec.h"
  45 #include "bytestream.h"
  46 #include "bitstream.h"
  47
  48 /* bitstream minipacket size */
  49 #define GIF_CHUNKS 100
  50
  51 /* slows down the decoding (and some browsers don't like it) */
  52 /* 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 */
  53 #define GIF_ADD_APP_HEADER // required to enable looping of animated gif
  54
  55 typedef struct {
  56     unsigned char r;
  57     unsigned char g;
  58     unsigned char b;
  59 } rgb_triplet;
  60
  61 /* we use the standard 216 color palette */
  62
  63 /* this script was used to create the palette:
  64  * 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
  65  *   echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
  66  */
  67
  68 static const rgb_triplet gif_clut[216] = {
  69     { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
  70     { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
  71     { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
  72     { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
  73     { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
  74     { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
  75     { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
  76     { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
  77     { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
  78     { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
  79     { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
  80     { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
  81     { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
  82     { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
  83     { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
  84     { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
  85     { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
  86     { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
  87     { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
  88     { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
  89     { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
  90     { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
  91     { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
  92     { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
  93     { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
  94     { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
  95     { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
  96     { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
  97     { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
  98     { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
  99     { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
 100     { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
 101     { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
 102     { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
 103     { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
 104     { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
 105 };
 106
 107 /* The GIF format uses reversed order for bitstreams... */
 108 /* at least they don't use PDP_ENDIAN :) */
 109 /* so we 'extend' PutBitContext. hmmm, OOP :) */
 110 /* seems this thing changed slightly since I wrote it... */
 111
 112 #ifdef ALT_BITSTREAM_WRITER
 113 # error no ALT_BITSTREAM_WRITER support for now
 114 #endif
 115
 116 static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
 117 {
 118     unsigned int bit_buf;
 119     int bit_cnt;
 120
 121     //    printf("put_bits=%d %x\n", n, value);
 122     assert(n == 32 || value < (1U << n));
 123
 124     bit_buf = s->bit_buf;
 125     bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
 126
 127     //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
 128     /* XXX: optimize */
 129     if (n < (32-bit_cnt)) {
 130         bit_buf |= value << (bit_cnt);
 131         bit_cnt+=n;
 132     } else {
 133         bit_buf |= value << (bit_cnt);
 134
 135         bytestream_put_le32(&s->buf_ptr, bit_buf);
 136
 137         //printf("bitbuf = %08x\n", bit_buf);
 138         if (s->buf_ptr >= s->buf_end)
 139             abort();
 140 //            flush_buffer_rev(s);
 141         bit_cnt=bit_cnt + n - 32;
 142         if (bit_cnt == 0) {
 143             bit_buf = 0;
 144         } else {
 145             bit_buf = value >> (n - bit_cnt);
 146         }
 147     }
 148
 149     s->bit_buf = bit_buf;
 150     s->bit_left = 32 - bit_cnt;
 151 }
 152
 153 /* pad the end of the output stream with zeros */
 154 static void gif_flush_put_bits_rev(PutBitContext *s)
 155 {
 156     while (s->bit_left < 32) {
 157         /* XXX: should test end of buffer */
 158         *s->buf_ptr++=s->bit_buf & 0xff;
 159         s->bit_buf>>=8;
 160         s->bit_left+=8;
 161     }
 162 //    flush_buffer_rev(s);
 163     s->bit_left=32;
 164     s->bit_buf=0;
 165 }
 166
 167 /* !RevPutBitContext */
 168
 169 /* GIF header */
 170 static int gif_image_write_header(uint8_t **bytestream,
 171                                   int width, int height, int loop_count,
 172                                   uint32_t *palette)
 173 {
 174     int i;
 175     unsigned int v;
 176
 177     bytestream_put_buffer(bytestream, "GIF", 3);
 178     bytestream_put_buffer(bytestream, "89a", 3);
 179     bytestream_put_le16(bytestream, width);
 180     bytestream_put_le16(bytestream, height);
 181
 182     bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
 183     bytestream_put_byte(bytestream, 0x1f); /* background color index */
 184     bytestream_put_byte(bytestream, 0); /* aspect ratio */
 185
 186     /* the global palette */
 187     if (!palette) {
 188         bytestream_put_buffer(bytestream, (const unsigned char *)gif_clut, 216*3);
 189         for(i=0;i<((256-216)*3);i++)
 190             bytestream_put_byte(bytestream, 0);
 191     } else {
 192         for(i=0;i<256;i++) {
 193             v = palette[i];
 194             bytestream_put_be24(bytestream, v);
 195         }
 196     }
 197
 198         /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
 199                 see http://members.aol.com/royalef/gifabout.htm#net-extension
 200
 201                 byte   1       : 33 (hex 0x21) GIF Extension code
 202                 byte   2       : 255 (hex 0xFF) Application Extension Label
 203                 byte   3       : 11 (hex (0x0B) Length of Application Block
 204                                          (eleven bytes of data to follow)
 205                 bytes  4 to 11 : "NETSCAPE"
 206                 bytes 12 to 14 : "2.0"
 207                 byte  15       : 3 (hex 0x03) Length of Data Sub-Block
 208                                          (three bytes of data to follow)
 209                 byte  16       : 1 (hex 0x01)
 210                 bytes 17 to 18 : 0 to 65535, an unsigned integer in
 211                                          lo-hi byte format. This indicate the
 212                                          number of iterations the loop should
 213                                          be executed.
 214                 bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
 215         */
 216
 217     /* application extension header */
 218 #ifdef GIF_ADD_APP_HEADER
 219     if (loop_count >= 0 && loop_count <= 65535) {
 220         bytestream_put_byte(bytestream, 0x21);
 221         bytestream_put_byte(bytestream, 0xff);
 222         bytestream_put_byte(bytestream, 0x0b);
 223         bytestream_put_buffer(bytestream, "NETSCAPE2.0", 11);  // bytes 4 to 14
 224         bytestream_put_byte(bytestream, 0x03); // byte 15
 225         bytestream_put_byte(bytestream, 0x01); // byte 16
 226         bytestream_put_le16(bytestream, (uint16_t)loop_count);
 227         bytestream_put_byte(bytestream, 0x00); // byte 19
 228     }
 229 #endif
 230     return 0;
 231 }
 232
 233 /* this is maybe slow, but allows for extensions */
 234 static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
 235 {
 236     return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
 237 }
 238
 239
 240 static int gif_image_write_image(uint8_t **bytestream,
 241                                  int x1, int y1, int width, int height,
 242                                  const uint8_t *buf, int linesize, int pix_fmt)
 243 {
 244     PutBitContext p;
 245     uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
 246     int i, left, w, v;
 247     const uint8_t *ptr;
 248     /* image block */
 249
 250     bytestream_put_byte(bytestream, 0x2c);
 251     bytestream_put_le16(bytestream, x1);
 252     bytestream_put_le16(bytestream, y1);
 253     bytestream_put_le16(bytestream, width);
 254     bytestream_put_le16(bytestream, height);
 255     bytestream_put_byte(bytestream, 0x00); /* flags */
 256     /* no local clut */
 257
 258     bytestream_put_byte(bytestream, 0x08);
 259
 260     left= width * height;
 261
 262     init_put_bits(&p, buffer, 130);
 263
 264 /*
 265  * the thing here is the bitstream is written as little packets, with a size byte before
 266  * but it's still the same bitstream between packets (no flush !)
 267  */
 268     ptr = buf;
 269     w = width;
 270     while(left>0) {
 271
 272         gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
 273
 274         for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
 275             if (pix_fmt == PIX_FMT_RGB24) {
 276                 v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
 277                 ptr+=3;
 278             } else {
 279                 v = *ptr++;
 280             }
 281             gif_put_bits_rev(&p, 9, v);
 282             if (--w == 0) {
 283                 w = width;
 284                 buf += linesize;
 285                 ptr = buf;
 286             }
 287         }
 288
 289         if(left<=GIF_CHUNKS) {
 290             gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
 291             gif_flush_put_bits_rev(&p);
 292         }
 293         if(pbBufPtr(&p) - p.buf > 0) {
 294             bytestream_put_byte(bytestream, pbBufPtr(&p) - p.buf); /* byte count of the packet */
 295             bytestream_put_buffer(bytestream, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
 296             p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
 297         }
 298         left-=GIF_CHUNKS;
 299     }
 300     bytestream_put_byte(bytestream, 0x00); /* end of image block */
 301     bytestream_put_byte(bytestream, 0x3b);
 302     return 0;
 303 }
 304
 305 typedef struct {
 306     int64_t time, file_time;
 307     uint8_t buffer[100]; /* data chunks */
 308     AVFrame picture;
 309 } GIFContext;
 310
 311 static av_cold int gif_encode_init(AVCodecContext *avctx)
 312 {
 313     GIFContext *s = avctx->priv_data;
 314
 315     avctx->coded_frame = &s->picture;
 316     return 0;
 317 }
 318
 319 /* better than nothing gif encoder */
 320 static int gif_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int buf_size, void *data)
 321 {
 322     GIFContext *s = avctx->priv_data;
 323     AVFrame *pict = data;
 324     AVFrame *const p = (AVFrame *)&s->picture;
 325     uint8_t *outbuf_ptr = outbuf;
 326
 327     *p = *pict;
 328     p->pict_type = FF_I_TYPE;
 329     p->key_frame = 1;
 330     gif_image_write_header(&outbuf_ptr, avctx->width, avctx->height, -1, (uint32_t *)pict->data[1]);
 331     gif_image_write_image(&outbuf_ptr, 0, 0, avctx->width, avctx->height, pict->data[0], pict->linesize[0], PIX_FMT_PAL8);
 332     return outbuf_ptr - outbuf;
 333 }
 334
 335 AVCodec gif_encoder = {
 336     "gif",
 337     CODEC_TYPE_VIDEO,
 338     CODEC_ID_GIF,
 339     sizeof(GIFContext),
 340     gif_encode_init,
 341     gif_encode_frame,
 342     NULL, //encode_end,
 343     .pix_fmts= (enum PixelFormat[]){PIX_FMT_PAL8, PIX_FMT_NONE},
 344     .long_name= "GIF (Graphics Interchange Format)",
 345 };