libavformat/gif.c

   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/put_bits.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
  57 typedef 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
  70 static 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 */
 110 static 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 */
 176 static 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
 182 static 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(put_bits_ptr(&p) - p.buf > 0) {
 236             put_byte(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
 237             put_buffer(pb, p.buf, put_bits_ptr(&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
 247 typedef struct {
 248     int64_t time, file_time;
 249     uint8_t buffer[100]; /* data chunks */
 250 } GIFContext;
 251
 252 static 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
 294 static 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
 329 static 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
 338 static 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
 347 AVOutputFormat 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 };