1/* 2 * GIF decoder 3 * Copyright (c) 2003 Fabrice Bellard 4 * Copyright (c) 2006 Baptiste Coudurier 5 * Copyright (c) 2012 Vitaliy E Sugrobov 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#include "libavutil/imgutils.h" 25#include "libavutil/opt.h" 26#include "avcodec.h" 27#include "bytestream.h" 28#include "internal.h" 29#include "lzw.h" 30#include "gif.h" 31 32/* This value is intentionally set to "transparent white" color. 33 * It is much better to have white background instead of black 34 * when gif image converted to format which not support transparency. 35 */ 36#define GIF_TRANSPARENT_COLOR 0x00ffffff 37 38typedef struct GifState { 39 const AVClass *class; 40 AVFrame *frame; 41 int screen_width; 42 int screen_height; 43 int has_global_palette; 44 int bits_per_pixel; 45 uint32_t bg_color; 46 int background_color_index; 47 int transparent_color_index; 48 int color_resolution; 49 /* intermediate buffer for storing color indices 50 * obtained from lzw-encoded data stream */ 51 uint8_t *idx_line; 52 int idx_line_size; 53 54 /* after the frame is displayed, the disposal method is used */ 55 int gce_prev_disposal; 56 int gce_disposal; 57 /* rectangle describing area that must be disposed */ 58 int gce_l, gce_t, gce_w, gce_h; 59 /* depending on disposal method we store either part of the image 60 * drawn on the canvas or background color that 61 * should be used upon disposal */ 62 uint32_t * stored_img; 63 int stored_img_size; 64 int stored_bg_color; 65 66 GetByteContext gb; 67 LZWState *lzw; 68 69 /* aux buffers */ 70 uint32_t global_palette[256]; 71 uint32_t local_palette[256]; 72 73 AVCodecContext *avctx; 74 int keyframe; 75 int keyframe_ok; 76 int trans_color; /**< color value that is used instead of transparent color */ 77} GifState; 78 79static void gif_read_palette(GifState *s, uint32_t *pal, int nb) 80{ 81 int i; 82 83 for (i = 0; i < nb; i++, pal++) 84 *pal = (0xffu << 24) | bytestream2_get_be24u(&s->gb); 85} 86 87static void gif_fill(AVFrame *picture, uint32_t color) 88{ 89 uint32_t *p = (uint32_t *)picture->data[0]; 90 uint32_t *p_end = p + (picture->linesize[0] / sizeof(uint32_t)) * picture->height; 91 92 for (; p < p_end; p++) 93 *p = color; 94} 95 96static void gif_fill_rect(AVFrame *picture, uint32_t color, int l, int t, int w, int h) 97{ 98 const int linesize = picture->linesize[0] / sizeof(uint32_t); 99 const uint32_t *py = (uint32_t *)picture->data[0] + t * linesize; 100 const uint32_t *pr, *pb = py + h * linesize; 101 uint32_t *px; 102 103 for (; py < pb; py += linesize) { 104 px = (uint32_t *)py + l; 105 pr = px + w; 106 107 for (; px < pr; px++) 108 *px = color; 109 } 110} 111 112static void gif_copy_img_rect(const uint32_t *src, uint32_t *dst, 113 int linesize, int l, int t, int w, int h) 114{ 115 const int y_start = t * linesize; 116 const uint32_t *src_px, 117 *src_py = src + y_start, 118 *dst_py = dst + y_start; 119 const uint32_t *src_pb = src_py + h * linesize; 120 uint32_t *dst_px; 121 122 for (; src_py < src_pb; src_py += linesize, dst_py += linesize) { 123 src_px = src_py + l; 124 dst_px = (uint32_t *)dst_py + l; 125 126 memcpy(dst_px, src_px, w * sizeof(uint32_t)); 127 } 128} 129 130static int gif_read_image(GifState *s, AVFrame *frame) 131{ 132 int left, top, width, height, bits_per_pixel, code_size, flags; 133 int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size; 134 uint32_t *ptr, *pal, *px, *pr, *ptr1; 135 int ret; 136 uint8_t *idx; 137 138 /* At least 9 bytes of Image Descriptor. */ 139 if (bytestream2_get_bytes_left(&s->gb) < 9) 140 return AVERROR_INVALIDDATA; 141 142 left = bytestream2_get_le16u(&s->gb); 143 top = bytestream2_get_le16u(&s->gb); 144 width = bytestream2_get_le16u(&s->gb); 145 height = bytestream2_get_le16u(&s->gb); 146 flags = bytestream2_get_byteu(&s->gb); 147 is_interleaved = flags & 0x40; 148 has_local_palette = flags & 0x80; 149 bits_per_pixel = (flags & 0x07) + 1; 150 151 av_dlog(s->avctx, "image x=%d y=%d w=%d h=%d\n", left, top, width, height); 152 153 if (has_local_palette) { 154 pal_size = 1 << bits_per_pixel; 155 156 if (bytestream2_get_bytes_left(&s->gb) < pal_size * 3) 157 return AVERROR_INVALIDDATA; 158 159 gif_read_palette(s, s->local_palette, pal_size); 160 pal = s->local_palette; 161 } else { 162 if (!s->has_global_palette) { 163 av_log(s->avctx, AV_LOG_ERROR, "picture doesn't have either global or local palette.\n"); 164 return AVERROR_INVALIDDATA; 165 } 166 167 pal = s->global_palette; 168 } 169 170 if (s->keyframe) { 171 if (s->transparent_color_index == -1 && s->has_global_palette) { 172 /* transparency wasn't set before the first frame, fill with background color */ 173 gif_fill(frame, s->bg_color); 174 } else { 175 /* otherwise fill with transparent color. 176 * this is necessary since by default picture filled with 0x80808080. */ 177 gif_fill(frame, s->trans_color); 178 } 179 } 180 181 /* verify that all the image is inside the screen dimensions */ 182 if (left + width > s->screen_width || 183 top + height > s->screen_height) { 184 av_log(s->avctx, AV_LOG_ERROR, "image is outside the screen dimensions.\n"); 185 return AVERROR_INVALIDDATA; 186 } 187 if (width <= 0 || height <= 0) { 188 av_log(s->avctx, AV_LOG_ERROR, "Invalid image dimensions.\n"); 189 return AVERROR_INVALIDDATA; 190 } 191 192 /* process disposal method */ 193 if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) { 194 gif_fill_rect(frame, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h); 195 } else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) { 196 gif_copy_img_rect(s->stored_img, (uint32_t *)frame->data[0], 197 frame->linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h); 198 } 199 200 s->gce_prev_disposal = s->gce_disposal; 201 202 if (s->gce_disposal != GCE_DISPOSAL_NONE) { 203 s->gce_l = left; s->gce_t = top; 204 s->gce_w = width; s->gce_h = height; 205 206 if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) { 207 if (s->transparent_color_index >= 0) 208 s->stored_bg_color = s->trans_color; 209 else 210 s->stored_bg_color = s->bg_color; 211 } else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) { 212 av_fast_malloc(&s->stored_img, &s->stored_img_size, frame->linesize[0] * frame->height); 213 if (!s->stored_img) 214 return AVERROR(ENOMEM); 215 216 gif_copy_img_rect((uint32_t *)frame->data[0], s->stored_img, 217 frame->linesize[0] / sizeof(uint32_t), left, top, width, height); 218 } 219 } 220 221 /* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */ 222 if (bytestream2_get_bytes_left(&s->gb) < 2) 223 return AVERROR_INVALIDDATA; 224 225 /* now get the image data */ 226 code_size = bytestream2_get_byteu(&s->gb); 227 if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->gb.buffer, 228 bytestream2_get_bytes_left(&s->gb), FF_LZW_GIF)) < 0) { 229 av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n"); 230 return ret; 231 } 232 233 /* read all the image */ 234 linesize = frame->linesize[0] / sizeof(uint32_t); 235 ptr1 = (uint32_t *)frame->data[0] + top * linesize + left; 236 ptr = ptr1; 237 pass = 0; 238 y1 = 0; 239 for (y = 0; y < height; y++) { 240 int count = ff_lzw_decode(s->lzw, s->idx_line, width); 241 if (count != width) { 242 if (count) 243 av_log(s->avctx, AV_LOG_ERROR, "LZW decode failed\n"); 244 goto decode_tail; 245 } 246 247 pr = ptr + width; 248 249 for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) { 250 if (*idx != s->transparent_color_index) 251 *px = pal[*idx]; 252 } 253 254 if (is_interleaved) { 255 switch(pass) { 256 default: 257 case 0: 258 case 1: 259 y1 += 8; 260 ptr += linesize * 8; 261 if (y1 >= height) { 262 y1 = pass ? 2 : 4; 263 ptr = ptr1 + linesize * y1; 264 pass++; 265 } 266 break; 267 case 2: 268 y1 += 4; 269 ptr += linesize * 4; 270 if (y1 >= height) { 271 y1 = 1; 272 ptr = ptr1 + linesize; 273 pass++; 274 } 275 break; 276 case 3: 277 y1 += 2; 278 ptr += linesize * 2; 279 break; 280 } 281 } else { 282 ptr += linesize; 283 } 284 } 285 286 decode_tail: 287 /* read the garbage data until end marker is found */ 288 ff_lzw_decode_tail(s->lzw); 289 290 /* Graphic Control Extension's scope is single frame. 291 * Remove its influence. */ 292 s->transparent_color_index = -1; 293 s->gce_disposal = GCE_DISPOSAL_NONE; 294 295 return 0; 296} 297 298static int gif_read_extension(GifState *s) 299{ 300 int ext_code, ext_len, gce_flags, gce_transparent_index; 301 302 /* There must be at least 2 bytes: 303 * 1 for extension label and 1 for extension length. */ 304 if (bytestream2_get_bytes_left(&s->gb) < 2) 305 return AVERROR_INVALIDDATA; 306 307 ext_code = bytestream2_get_byteu(&s->gb); 308 ext_len = bytestream2_get_byteu(&s->gb); 309 310 av_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len); 311 312 switch(ext_code) { 313 case GIF_GCE_EXT_LABEL: 314 if (ext_len != 4) 315 goto discard_ext; 316 317 /* We need at least 5 bytes more: 4 is for extension body 318 * and 1 for next block size. */ 319 if (bytestream2_get_bytes_left(&s->gb) < 5) 320 return AVERROR_INVALIDDATA; 321 322 gce_flags = bytestream2_get_byteu(&s->gb); 323 bytestream2_skipu(&s->gb, 2); // delay during which the frame is shown 324 gce_transparent_index = bytestream2_get_byteu(&s->gb); 325 if (gce_flags & 0x01) 326 s->transparent_color_index = gce_transparent_index; 327 else 328 s->transparent_color_index = -1; 329 s->gce_disposal = (gce_flags >> 2) & 0x7; 330 331 av_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n", 332 gce_flags, 333 s->transparent_color_index, s->gce_disposal); 334 335 if (s->gce_disposal > 3) { 336 s->gce_disposal = GCE_DISPOSAL_NONE; 337 av_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len); 338 } 339 340 ext_len = bytestream2_get_byteu(&s->gb); 341 break; 342 } 343 344 /* NOTE: many extension blocks can come after */ 345 discard_ext: 346 while (ext_len) { 347 /* There must be at least ext_len bytes and 1 for next block size byte. */ 348 if (bytestream2_get_bytes_left(&s->gb) < ext_len + 1) 349 return AVERROR_INVALIDDATA; 350 351 bytestream2_skipu(&s->gb, ext_len); 352 ext_len = bytestream2_get_byteu(&s->gb); 353 354 av_dlog(s->avctx, "ext_len1=%d\n", ext_len); 355 } 356 return 0; 357} 358 359static int gif_read_header1(GifState *s) 360{ 361 uint8_t sig[6]; 362 int v, n; 363 int background_color_index; 364 365 if (bytestream2_get_bytes_left(&s->gb) < 13) 366 return AVERROR_INVALIDDATA; 367 368 /* read gif signature */ 369 bytestream2_get_bufferu(&s->gb, sig, 6); 370 if (memcmp(sig, gif87a_sig, 6) && 371 memcmp(sig, gif89a_sig, 6)) 372 return AVERROR_INVALIDDATA; 373 374 /* read screen header */ 375 s->transparent_color_index = -1; 376 s->screen_width = bytestream2_get_le16u(&s->gb); 377 s->screen_height = bytestream2_get_le16u(&s->gb); 378 379 v = bytestream2_get_byteu(&s->gb); 380 s->color_resolution = ((v & 0x70) >> 4) + 1; 381 s->has_global_palette = (v & 0x80); 382 s->bits_per_pixel = (v & 0x07) + 1; 383 background_color_index = bytestream2_get_byteu(&s->gb); 384 n = bytestream2_get_byteu(&s->gb); 385 if (n) { 386 s->avctx->sample_aspect_ratio.num = n + 15; 387 s->avctx->sample_aspect_ratio.den = 64; 388 } 389 390 av_dlog(s->avctx, "screen_w=%d screen_h=%d bpp=%d global_palette=%d\n", 391 s->screen_width, s->screen_height, s->bits_per_pixel, 392 s->has_global_palette); 393 394 if (s->has_global_palette) { 395 s->background_color_index = background_color_index; 396 n = 1 << s->bits_per_pixel; 397 if (bytestream2_get_bytes_left(&s->gb) < n * 3) 398 return AVERROR_INVALIDDATA; 399 400 gif_read_palette(s, s->global_palette, n); 401 s->bg_color = s->global_palette[s->background_color_index]; 402 } else 403 s->background_color_index = -1; 404 405 return 0; 406} 407 408static int gif_parse_next_image(GifState *s, AVFrame *frame) 409{ 410 while (bytestream2_get_bytes_left(&s->gb) > 0) { 411 int code = bytestream2_get_byte(&s->gb); 412 int ret; 413 414 av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code); 415 416 switch (code) { 417 case GIF_IMAGE_SEPARATOR: 418 return gif_read_image(s, frame); 419 case GIF_EXTENSION_INTRODUCER: 420 if ((ret = gif_read_extension(s)) < 0) 421 return ret; 422 break; 423 case GIF_TRAILER: 424 /* end of image */ 425 return AVERROR_EOF; 426 default: 427 /* erroneous block label */ 428 return AVERROR_INVALIDDATA; 429 } 430 } 431 return AVERROR_EOF; 432} 433 434static av_cold int gif_decode_init(AVCodecContext *avctx) 435{ 436 GifState *s = avctx->priv_data; 437 438 s->avctx = avctx; 439 440 avctx->pix_fmt = AV_PIX_FMT_RGB32; 441 s->frame = av_frame_alloc(); 442 if (!s->frame) 443 return AVERROR(ENOMEM); 444 ff_lzw_decode_open(&s->lzw); 445 return 0; 446} 447 448static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt) 449{ 450 GifState *s = avctx->priv_data; 451 int ret; 452 453 bytestream2_init(&s->gb, avpkt->data, avpkt->size); 454 455 s->frame->pts = avpkt->pts; 456 s->frame->pkt_pts = avpkt->pts; 457 s->frame->pkt_dts = avpkt->dts; 458 av_frame_set_pkt_duration(s->frame, avpkt->duration); 459 460 if (avpkt->size >= 6) { 461 s->keyframe = memcmp(avpkt->data, gif87a_sig, 6) == 0 || 462 memcmp(avpkt->data, gif89a_sig, 6) == 0; 463 } else { 464 s->keyframe = 0; 465 } 466 467 if (s->keyframe) { 468 s->keyframe_ok = 0; 469 s->gce_prev_disposal = GCE_DISPOSAL_NONE; 470 if ((ret = gif_read_header1(s)) < 0) 471 return ret; 472 473 if ((ret = ff_set_dimensions(avctx, s->screen_width, s->screen_height)) < 0) 474 return ret; 475 476 av_frame_unref(s->frame); 477 if ((ret = ff_get_buffer(avctx, s->frame, 0)) < 0) 478 return ret; 479 480 av_fast_malloc(&s->idx_line, &s->idx_line_size, s->screen_width); 481 if (!s->idx_line) 482 return AVERROR(ENOMEM); 483 484 s->frame->pict_type = AV_PICTURE_TYPE_I; 485 s->frame->key_frame = 1; 486 s->keyframe_ok = 1; 487 } else { 488 if (!s->keyframe_ok) { 489 av_log(avctx, AV_LOG_ERROR, "cannot decode frame without keyframe\n"); 490 return AVERROR_INVALIDDATA; 491 } 492 493 if ((ret = ff_reget_buffer(avctx, s->frame)) < 0) 494 return ret; 495 496 s->frame->pict_type = AV_PICTURE_TYPE_P; 497 s->frame->key_frame = 0; 498 } 499 500 ret = gif_parse_next_image(s, s->frame); 501 if (ret < 0) 502 return ret; 503 504 if ((ret = av_frame_ref(data, s->frame)) < 0) 505 return ret; 506 *got_frame = 1; 507 508 return bytestream2_tell(&s->gb); 509} 510 511static av_cold int gif_decode_close(AVCodecContext *avctx) 512{ 513 GifState *s = avctx->priv_data; 514 515 ff_lzw_decode_close(&s->lzw); 516 av_frame_free(&s->frame); 517 av_freep(&s->idx_line); 518 av_freep(&s->stored_img); 519 520 return 0; 521} 522 523static const AVOption options[] = { 524 { "trans_color", "color value (ARGB) that is used instead of transparent color", 525 offsetof(GifState, trans_color), AV_OPT_TYPE_INT, 526 {.i64 = GIF_TRANSPARENT_COLOR}, 0, 0xffffffff, 527 AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM }, 528 { NULL }, 529}; 530 531static const AVClass decoder_class = { 532 .class_name = "gif decoder", 533 .item_name = av_default_item_name, 534 .option = options, 535 .version = LIBAVUTIL_VERSION_INT, 536 .category = AV_CLASS_CATEGORY_DECODER, 537}; 538 539AVCodec ff_gif_decoder = { 540 .name = "gif", 541 .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"), 542 .type = AVMEDIA_TYPE_VIDEO, 543 .id = AV_CODEC_ID_GIF, 544 .priv_data_size = sizeof(GifState), 545 .init = gif_decode_init, 546 .close = gif_decode_close, 547 .decode = gif_decode_frame, 548 .capabilities = CODEC_CAP_DR1, 549 .priv_class = &decoder_class, 550}; 551