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
  47 /* The GIF format uses reversed order for bitstreams... */
  48 /* at least they don't use PDP_ENDIAN :) */
  49 #define BITSTREAM_WRITER_LE
  50
  51 #include "bitstream.h"
  52
  53 /* bitstream minipacket size */
  54 #define GIF_CHUNKS 100
  55
  56 /* slows down the decoding (and some browsers don't like it) */
  57 /* 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 */
  58 #define GIF_ADD_APP_HEADER // required to enable looping of animated gif
  59
  60 typedef struct {
  61     unsigned char r;
  62     unsigned char g;
  63     unsigned char b;
  64 } rgb_triplet;
  65
  66 /* we use the standard 216 color palette */
  67
  68 /* this script was used to create the palette:
  69  * 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
  70  *   echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
  71  */
  72
  73 static const rgb_triplet gif_clut[216] = {
  74     { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
  75     { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
  76     { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
  77     { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
  78     { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
  79     { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
  80     { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
  81     { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
  82     { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
  83     { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
  84     { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
  85     { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
  86     { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
  87     { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
  88     { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
  89     { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
  90     { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
  91     { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
  92     { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
  93     { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
  94     { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
  95     { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
  96     { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
  97     { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
  98     { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
  99     { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
 100     { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
 101     { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
 102     { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
 103     { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
 104     { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
 105     { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
 106     { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
 107     { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
 108     { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
 109     { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
 110 };
 111
 112 /* GIF header */
 113 static int gif_image_write_header(uint8_t **bytestream,
 114                                   int width, int height, int loop_count,
 115                                   uint32_t *palette)
 116 {
 117     int i;
 118     unsigned int v;
 119
 120     bytestream_put_buffer(bytestream, "GIF", 3);
 121     bytestream_put_buffer(bytestream, "89a", 3);
 122     bytestream_put_le16(bytestream, width);
 123     bytestream_put_le16(bytestream, height);
 124
 125     bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
 126     bytestream_put_byte(bytestream, 0x1f); /* background color index */
 127     bytestream_put_byte(bytestream, 0); /* aspect ratio */
 128
 129     /* the global palette */
 130     if (!palette) {
 131         bytestream_put_buffer(bytestream, (const unsigned char *)gif_clut, 216*3);
 132         for(i=0;i<((256-216)*3);i++)
 133             bytestream_put_byte(bytestream, 0);
 134     } else {
 135         for(i=0;i<256;i++) {
 136             v = palette[i];
 137             bytestream_put_be24(bytestream, v);
 138         }
 139     }
 140
 141         /*        update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
 142                 see http://members.aol.com/royalef/gifabout.htm#net-extension
 143
 144                 byte   1       : 33 (hex 0x21) GIF Extension code
 145                 byte   2       : 255 (hex 0xFF) Application Extension Label
 146                 byte   3       : 11 (hex (0x0B) Length of Application Block
 147                                          (eleven bytes of data to follow)
 148                 bytes  4 to 11 : "NETSCAPE"
 149                 bytes 12 to 14 : "2.0"
 150                 byte  15       : 3 (hex 0x03) Length of Data Sub-Block
 151                                          (three bytes of data to follow)
 152                 byte  16       : 1 (hex 0x01)
 153                 bytes 17 to 18 : 0 to 65535, an unsigned integer in
 154                                          lo-hi byte format. This indicate the
 155                                          number of iterations the loop should
 156                                          be executed.
 157                 bytes 19       : 0 (hex 0x00) a Data Sub-block Terminator
 158         */
 159
 160     /* application extension header */
 161 #ifdef GIF_ADD_APP_HEADER
 162     if (loop_count >= 0 && loop_count <= 65535) {
 163         bytestream_put_byte(bytestream, 0x21);
 164         bytestream_put_byte(bytestream, 0xff);
 165         bytestream_put_byte(bytestream, 0x0b);
 166         bytestream_put_buffer(bytestream, "NETSCAPE2.0", 11);  // bytes 4 to 14
 167         bytestream_put_byte(bytestream, 0x03); // byte 15
 168         bytestream_put_byte(bytestream, 0x01); // byte 16
 169         bytestream_put_le16(bytestream, (uint16_t)loop_count);
 170         bytestream_put_byte(bytestream, 0x00); // byte 19
 171     }
 172 #endif
 173     return 0;
 174 }
 175
 176 /* this is maybe slow, but allows for extensions */
 177 static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
 178 {
 179     return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
 180 }
 181
 182
 183 static int gif_image_write_image(uint8_t **bytestream,
 184                                  int x1, int y1, int width, int height,
 185                                  const uint8_t *buf, int linesize, int pix_fmt)
 186 {
 187     PutBitContext p;
 188     uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
 189     int i, left, w, v;
 190     const uint8_t *ptr;
 191     /* image block */
 192
 193     bytestream_put_byte(bytestream, 0x2c);
 194     bytestream_put_le16(bytestream, x1);
 195     bytestream_put_le16(bytestream, y1);
 196     bytestream_put_le16(bytestream, width);
 197     bytestream_put_le16(bytestream, height);
 198     bytestream_put_byte(bytestream, 0x00); /* flags */
 199     /* no local clut */
 200
 201     bytestream_put_byte(bytestream, 0x08);
 202
 203     left= width * height;
 204
 205     init_put_bits(&p, buffer, 130);
 206
 207 /*
 208  * the thing here is the bitstream is written as little packets, with a size byte before
 209  * but it's still the same bitstream between packets (no flush !)
 210  */
 211     ptr = buf;
 212     w = width;
 213     while(left>0) {
 214
 215         put_bits(&p, 9, 0x0100); /* clear code */
 216
 217         for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
 218             if (pix_fmt == PIX_FMT_RGB24) {
 219                 v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
 220                 ptr+=3;
 221             } else {
 222                 v = *ptr++;
 223             }
 224             put_bits(&p, 9, v);
 225             if (--w == 0) {
 226                 w = width;
 227                 buf += linesize;
 228                 ptr = buf;
 229             }
 230         }
 231
 232         if(left<=GIF_CHUNKS) {
 233             put_bits(&p, 9, 0x101); /* end of stream */
 234             flush_put_bits(&p);
 235         }
 236         if(pbBufPtr(&p) - p.buf > 0) {
 237             bytestream_put_byte(bytestream, pbBufPtr(&p) - p.buf); /* byte count of the packet */
 238             bytestream_put_buffer(bytestream, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
 239             p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
 240         }
 241         left-=GIF_CHUNKS;
 242     }
 243     bytestream_put_byte(bytestream, 0x00); /* end of image block */
 244     bytestream_put_byte(bytestream, 0x3b);
 245     return 0;
 246 }
 247
 248 typedef struct {
 249     int64_t time, file_time;
 250     uint8_t buffer[100]; /* data chunks */
 251     AVFrame picture;
 252 } GIFContext;
 253
 254 static av_cold int gif_encode_init(AVCodecContext *avctx)
 255 {
 256     GIFContext *s = avctx->priv_data;
 257
 258     avctx->coded_frame = &s->picture;
 259     return 0;
 260 }
 261
 262 /* better than nothing gif encoder */
 263 static int gif_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int buf_size, void *data)
 264 {
 265     GIFContext *s = avctx->priv_data;
 266     AVFrame *pict = data;
 267     AVFrame *const p = (AVFrame *)&s->picture;
 268     uint8_t *outbuf_ptr = outbuf;
 269
 270     *p = *pict;
 271     p->pict_type = FF_I_TYPE;
 272     p->key_frame = 1;
 273     gif_image_write_header(&outbuf_ptr, avctx->width, avctx->height, -1, (uint32_t *)pict->data[1]);
 274     gif_image_write_image(&outbuf_ptr, 0, 0, avctx->width, avctx->height, pict->data[0], pict->linesize[0], PIX_FMT_PAL8);
 275     return outbuf_ptr - outbuf;
 276 }
 277
 278 AVCodec gif_encoder = {
 279     "gif",
 280     CODEC_TYPE_VIDEO,
 281     CODEC_ID_GIF,
 282     sizeof(GIFContext),
 283     gif_encode_init,
 284     gif_encode_frame,
 285     NULL, //encode_end,
 286     .pix_fmts= (enum PixelFormat[]){PIX_FMT_PAL8, PIX_FMT_NONE},
 287     .long_name= NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
 288 };