Libav 0.7.1
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00001 /* 00002 * Animated GIF muxer 00003 * Copyright (c) 2000 Fabrice Bellard 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * Libav is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with Libav; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00022 /* 00023 * First version by Francois Revol revol@free.fr 00024 * 00025 * Features and limitations: 00026 * - currently no compression is performed, 00027 * in fact the size of the data is 9/8 the size of the image in 8bpp 00028 * - uses only a global standard palette 00029 * - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS). 00030 * 00031 * Reference documents: 00032 * http://www.goice.co.jp/member/mo/formats/gif.html 00033 * http://astronomy.swin.edu.au/pbourke/dataformats/gif/ 00034 * http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt 00035 * 00036 * this url claims to have an LZW algorithm not covered by Unisys patent: 00037 * http://www.msg.net/utility/whirlgif/gifencod.html 00038 * could help reduce the size of the files _a lot_... 00039 * some sites mentions an RLE type compression also. 00040 */ 00041 00042 #include "avformat.h" 00043 00044 /* The GIF format uses reversed order for bitstreams... */ 00045 /* at least they don't use PDP_ENDIAN :) */ 00046 #define BITSTREAM_WRITER_LE 00047 00048 #include "libavcodec/put_bits.h" 00049 00050 /* bitstream minipacket size */ 00051 #define GIF_CHUNKS 100 00052 00053 /* slows down the decoding (and some browsers don't like it) */ 00054 /* 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 */ 00055 #define GIF_ADD_APP_HEADER // required to enable looping of animated gif 00056 00057 typedef struct { 00058 unsigned char r; 00059 unsigned char g; 00060 unsigned char b; 00061 } rgb_triplet; 00062 00063 /* we use the standard 216 color palette */ 00064 00065 /* this script was used to create the palette: 00066 * 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 00067 * echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done 00068 */ 00069 00070 static const rgb_triplet gif_clut[216] = { 00071 { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff }, 00072 { 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff }, 00073 { 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff }, 00074 { 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff }, 00075 { 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff }, 00076 { 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff }, 00077 { 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff }, 00078 { 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff }, 00079 { 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff }, 00080 { 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff }, 00081 { 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff }, 00082 { 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff }, 00083 { 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff }, 00084 { 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff }, 00085 { 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff }, 00086 { 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff }, 00087 { 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff }, 00088 { 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff }, 00089 { 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff }, 00090 { 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff }, 00091 { 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff }, 00092 { 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff }, 00093 { 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff }, 00094 { 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff }, 00095 { 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff }, 00096 { 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff }, 00097 { 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff }, 00098 { 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff }, 00099 { 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff }, 00100 { 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff }, 00101 { 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff }, 00102 { 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff }, 00103 { 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff }, 00104 { 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff }, 00105 { 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff }, 00106 { 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff }, 00107 }; 00108 00109 /* GIF header */ 00110 static int gif_image_write_header(AVIOContext *pb, 00111 int width, int height, int loop_count, 00112 uint32_t *palette) 00113 { 00114 int i; 00115 unsigned int v; 00116 00117 avio_write(pb, "GIF", 3); 00118 avio_write(pb, "89a", 3); 00119 avio_wl16(pb, width); 00120 avio_wl16(pb, height); 00121 00122 avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */ 00123 avio_w8(pb, 0x1f); /* background color index */ 00124 avio_w8(pb, 0); /* aspect ratio */ 00125 00126 /* the global palette */ 00127 if (!palette) { 00128 avio_write(pb, (const unsigned char *)gif_clut, 216*3); 00129 for(i=0;i<((256-216)*3);i++) 00130 avio_w8(pb, 0); 00131 } else { 00132 for(i=0;i<256;i++) { 00133 v = palette[i]; 00134 avio_w8(pb, (v >> 16) & 0xff); 00135 avio_w8(pb, (v >> 8) & 0xff); 00136 avio_w8(pb, (v) & 0xff); 00137 } 00138 } 00139 00140 /* update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif 00141 see http://members.aol.com/royalef/gifabout.htm#net-extension 00142 00143 byte 1 : 33 (hex 0x21) GIF Extension code 00144 byte 2 : 255 (hex 0xFF) Application Extension Label 00145 byte 3 : 11 (hex (0x0B) Length of Application Block 00146 (eleven bytes of data to follow) 00147 bytes 4 to 11 : "NETSCAPE" 00148 bytes 12 to 14 : "2.0" 00149 byte 15 : 3 (hex 0x03) Length of Data Sub-Block 00150 (three bytes of data to follow) 00151 byte 16 : 1 (hex 0x01) 00152 bytes 17 to 18 : 0 to 65535, an unsigned integer in 00153 lo-hi byte format. This indicate the 00154 number of iterations the loop should 00155 be executed. 00156 bytes 19 : 0 (hex 0x00) a Data Sub-block Terminator 00157 */ 00158 00159 /* application extension header */ 00160 #ifdef GIF_ADD_APP_HEADER 00161 if (loop_count >= 0 && loop_count <= 65535) { 00162 avio_w8(pb, 0x21); 00163 avio_w8(pb, 0xff); 00164 avio_w8(pb, 0x0b); 00165 avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1); // bytes 4 to 14 00166 avio_w8(pb, 0x03); // byte 15 00167 avio_w8(pb, 0x01); // byte 16 00168 avio_wl16(pb, (uint16_t)loop_count); 00169 avio_w8(pb, 0x00); // byte 19 00170 } 00171 #endif 00172 return 0; 00173 } 00174 00175 /* this is maybe slow, but allows for extensions */ 00176 static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b) 00177 { 00178 return (((r) / 47) % 6) * 6 * 6 + (((g) / 47) % 6) * 6 + (((b) / 47) % 6); 00179 } 00180 00181 00182 static int gif_image_write_image(AVIOContext *pb, 00183 int x1, int y1, int width, int height, 00184 const uint8_t *buf, int linesize, int pix_fmt) 00185 { 00186 PutBitContext p; 00187 uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */ 00188 int i, left, w, v; 00189 const uint8_t *ptr; 00190 /* image block */ 00191 00192 avio_w8(pb, 0x2c); 00193 avio_wl16(pb, x1); 00194 avio_wl16(pb, y1); 00195 avio_wl16(pb, width); 00196 avio_wl16(pb, height); 00197 avio_w8(pb, 0x00); /* flags */ 00198 /* no local clut */ 00199 00200 avio_w8(pb, 0x08); 00201 00202 left= width * height; 00203 00204 init_put_bits(&p, buffer, 130); 00205 00206 /* 00207 * the thing here is the bitstream is written as little packets, with a size byte before 00208 * but it's still the same bitstream between packets (no flush !) 00209 */ 00210 ptr = buf; 00211 w = width; 00212 while(left>0) { 00213 00214 put_bits(&p, 9, 0x0100); /* clear code */ 00215 00216 for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) { 00217 if (pix_fmt == PIX_FMT_RGB24) { 00218 v = gif_clut_index(ptr[0], ptr[1], ptr[2]); 00219 ptr+=3; 00220 } else { 00221 v = *ptr++; 00222 } 00223 put_bits(&p, 9, v); 00224 if (--w == 0) { 00225 w = width; 00226 buf += linesize; 00227 ptr = buf; 00228 } 00229 } 00230 00231 if(left<=GIF_CHUNKS) { 00232 put_bits(&p, 9, 0x101); /* end of stream */ 00233 flush_put_bits(&p); 00234 } 00235 if(put_bits_ptr(&p) - p.buf > 0) { 00236 avio_w8(pb, put_bits_ptr(&p) - p.buf); /* byte count of the packet */ 00237 avio_write(pb, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */ 00238 p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */ 00239 } 00240 left-=GIF_CHUNKS; 00241 } 00242 avio_w8(pb, 0x00); /* end of image block */ 00243 00244 return 0; 00245 } 00246 00247 typedef struct { 00248 int64_t time, file_time; 00249 uint8_t buffer[100]; /* data chunks */ 00250 } GIFContext; 00251 00252 static int gif_write_header(AVFormatContext *s) 00253 { 00254 GIFContext *gif = s->priv_data; 00255 AVIOContext *pb = s->pb; 00256 AVCodecContext *enc, *video_enc; 00257 int i, width, height, loop_count /*, rate*/; 00258 00259 /* XXX: do we reject audio streams or just ignore them ? 00260 if(s->nb_streams > 1) 00261 return -1; 00262 */ 00263 gif->time = 0; 00264 gif->file_time = 0; 00265 00266 video_enc = NULL; 00267 for(i=0;i<s->nb_streams;i++) { 00268 enc = s->streams[i]->codec; 00269 if (enc->codec_type != AVMEDIA_TYPE_AUDIO) 00270 video_enc = enc; 00271 } 00272 00273 if (!video_enc) { 00274 av_free(gif); 00275 return -1; 00276 } else { 00277 width = video_enc->width; 00278 height = video_enc->height; 00279 loop_count = s->loop_output; 00280 // rate = video_enc->time_base.den; 00281 } 00282 00283 if (video_enc->pix_fmt != PIX_FMT_RGB24) { 00284 av_log(s, AV_LOG_ERROR, "ERROR: gif only handles the rgb24 pixel format. Use -pix_fmt rgb24.\n"); 00285 return AVERROR(EIO); 00286 } 00287 00288 gif_image_write_header(pb, width, height, loop_count, NULL); 00289 00290 avio_flush(s->pb); 00291 return 0; 00292 } 00293 00294 static int gif_write_video(AVFormatContext *s, 00295 AVCodecContext *enc, const uint8_t *buf, int size) 00296 { 00297 AVIOContext *pb = s->pb; 00298 int jiffies; 00299 00300 /* graphic control extension block */ 00301 avio_w8(pb, 0x21); 00302 avio_w8(pb, 0xf9); 00303 avio_w8(pb, 0x04); /* block size */ 00304 avio_w8(pb, 0x04); /* flags */ 00305 00306 /* 1 jiffy is 1/70 s */ 00307 /* the delay_time field indicates the number of jiffies - 1 */ 00308 /* XXX: should use delay, in order to be more accurate */ 00309 /* instead of using the same rounded value each time */ 00310 /* XXX: don't even remember if I really use it for now */ 00311 jiffies = (70*enc->time_base.num/enc->time_base.den) - 1; 00312 00313 avio_wl16(pb, jiffies); 00314 00315 avio_w8(pb, 0x1f); /* transparent color index */ 00316 avio_w8(pb, 0x00); 00317 00318 gif_image_write_image(pb, 0, 0, enc->width, enc->height, 00319 buf, enc->width * 3, PIX_FMT_RGB24); 00320 00321 avio_flush(s->pb); 00322 return 0; 00323 } 00324 00325 static int gif_write_packet(AVFormatContext *s, AVPacket *pkt) 00326 { 00327 AVCodecContext *codec = s->streams[pkt->stream_index]->codec; 00328 if (codec->codec_type == AVMEDIA_TYPE_AUDIO) 00329 return 0; /* just ignore audio */ 00330 else 00331 return gif_write_video(s, codec, pkt->data, pkt->size); 00332 } 00333 00334 static int gif_write_trailer(AVFormatContext *s) 00335 { 00336 AVIOContext *pb = s->pb; 00337 00338 avio_w8(pb, 0x3b); 00339 avio_flush(s->pb); 00340 return 0; 00341 } 00342 00343 AVOutputFormat ff_gif_muxer = { 00344 "gif", 00345 NULL_IF_CONFIG_SMALL("GIF Animation"), 00346 "image/gif", 00347 "gif", 00348 sizeof(GIFContext), 00349 CODEC_ID_NONE, 00350 CODEC_ID_RAWVIDEO, 00351 gif_write_header, 00352 gif_write_packet, 00353 gif_write_trailer, 00354 };