FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/gifdec.c
Date: 2022-07-05 19:52:29
Exec Total Coverage
Lines: 201 272 73.9%
Branches: 89 139 64.0%
Line Branch Exec Source
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 "codec_internal.h"
29 #include "internal.h"
30 #include "lzw.h"
31 #include "gif.h"
32
33 /* This value is intentionally set to "transparent white" color.
34 * It is much better to have white background instead of black
35 * when gif image converted to format which not support transparency.
36 */
37 #define GIF_TRANSPARENT_COLOR 0x00ffffff
38
39 typedef struct GifState {
40 const AVClass *class;
41 AVFrame *frame;
42 int screen_width;
43 int screen_height;
44 int has_global_palette;
45 int bits_per_pixel;
46 uint32_t bg_color;
47 int background_color_index;
48 int transparent_color_index;
49 int color_resolution;
50 /* intermediate buffer for storing color indices
51 * obtained from lzw-encoded data stream */
52 uint8_t *idx_line;
53 int idx_line_size;
54
55 /* after the frame is displayed, the disposal method is used */
56 int gce_prev_disposal;
57 int gce_disposal;
58 /* rectangle describing area that must be disposed */
59 int gce_l, gce_t, gce_w, gce_h;
60 /* depending on disposal method we store either part of the image
61 * drawn on the canvas or background color that
62 * should be used upon disposal */
63 uint32_t * stored_img;
64 int stored_img_size;
65 int stored_bg_color;
66
67 GetByteContext gb;
68 LZWState *lzw;
69
70 /* aux buffers */
71 uint32_t global_palette[256];
72 uint32_t local_palette[256];
73
74 AVCodecContext *avctx;
75 int keyframe;
76 int keyframe_ok;
77 int trans_color; /**< color value that is used instead of transparent color */
78 } GifState;
79
80 1219 static void gif_read_palette(GifState *s, uint32_t *pal, int nb)
81 {
82 int i;
83
84
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 300547 for (i = 0; i < nb; i++, pal++)
85 299328 *pal = (0xffu << 24) | bytestream2_get_be24u(&s->gb);
86 1219 }
87
88 13 static void gif_fill(AVFrame *picture, uint32_t color)
89 {
90 13 uint32_t *p = (uint32_t *)picture->data[0];
91 13 uint32_t *p_end = p + (picture->linesize[0] / sizeof(uint32_t)) * picture->height;
92
93
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 727197 for (; p < p_end; p++)
94 727184 *p = color;
95 13 }
96
97 6 static void gif_fill_rect(AVFrame *picture, uint32_t color, int l, int t, int w, int h)
98 {
99 6 const int linesize = picture->linesize[0] / sizeof(uint32_t);
100 6 const uint32_t *py = (uint32_t *)picture->data[0] + t * linesize;
101 6 const uint32_t *pr, *pb = py + h * linesize;
102 uint32_t *px;
103
104
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 222 for (; py < pb; py += linesize) {
105 216 px = (uint32_t *)py + l;
106 216 pr = px + w;
107
108
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 15768 for (; px < pr; px++)
109 15552 *px = color;
110 }
111 6 }
112
113 3 static void gif_copy_img_rect(const uint32_t *src, uint32_t *dst,
114 int linesize, int l, int t, int w, int h)
115 {
116 3 const int y_start = t * linesize;
117 const uint32_t *src_px,
118 3 *src_py = src + y_start,
119 3 *dst_py = dst + y_start;
120 3 const uint32_t *src_pb = src_py + h * linesize;
121 uint32_t *dst_px;
122
123
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 183 for (; src_py < src_pb; src_py += linesize, dst_py += linesize) {
124 180 src_px = src_py + l;
125 180 dst_px = (uint32_t *)dst_py + l;
126
127 180 memcpy(dst_px, src_px, w * sizeof(uint32_t));
128 }
129 3 }
130
131 1294 static int gif_read_image(GifState *s, AVFrame *frame)
132 {
133 int left, top, width, height, bits_per_pixel, code_size, flags, pw;
134 int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size, lzwed_len;
135 uint32_t *ptr, *pal, *px, *pr, *ptr1;
136 int ret;
137 uint8_t *idx;
138
139 /* At least 9 bytes of Image Descriptor. */
140
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 1294 if (bytestream2_get_bytes_left(&s->gb) < 9)
141 ✗ return AVERROR_INVALIDDATA;
142
143 1294 left = bytestream2_get_le16u(&s->gb);
144 1294 top = bytestream2_get_le16u(&s->gb);
145 1294 width = bytestream2_get_le16u(&s->gb);
146 1294 height = bytestream2_get_le16u(&s->gb);
147 1294 flags = bytestream2_get_byteu(&s->gb);
148 1294 is_interleaved = flags & 0x40;
149 1294 has_local_palette = flags & 0x80;
150 1294 bits_per_pixel = (flags & 0x07) + 1;
151
152 ff_dlog(s->avctx, "image x=%d y=%d w=%d h=%d\n", left, top, width, height);
153
154
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 1294 if (has_local_palette) {
155 1213 pal_size = 1 << bits_per_pixel;
156
157
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 1213 if (bytestream2_get_bytes_left(&s->gb) < pal_size * 3)
158 ✗ return AVERROR_INVALIDDATA;
159
160 1213 gif_read_palette(s, s->local_palette, pal_size);
161 1213 pal = s->local_palette;
162 } else {
163
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 81 if (!s->has_global_palette) {
164 ✗ av_log(s->avctx, AV_LOG_ERROR, "picture doesn't have either global or local palette.\n");
165 ✗ return AVERROR_INVALIDDATA;
166 }
167
168 81 pal = s->global_palette;
169 }
170
171
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 1294 if (s->keyframe) {
172
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 13 if (s->transparent_color_index == -1 && s->has_global_palette) {
173 /* transparency wasn't set before the first frame, fill with background color */
174 5 gif_fill(frame, s->bg_color);
175 } else {
176 /* otherwise fill with transparent color.
177 * this is necessary since by default picture filled with 0x80808080. */
178 8 gif_fill(frame, s->trans_color);
179 }
180 }
181
182 /* verify that all the image is inside the screen dimensions */
183
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 1294 if (!width || width > s->screen_width) {
184 ✗ av_log(s->avctx, AV_LOG_WARNING, "Invalid image width: %d, truncating.\n", width);
185 ✗ width = s->screen_width;
186 }
187
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 1294 if (left >= s->screen_width) {
188 ✗ av_log(s->avctx, AV_LOG_ERROR, "Invalid left position: %d.\n", left);
189 ✗ return AVERROR_INVALIDDATA;
190 }
191
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 1294 if (!height || height > s->screen_height) {
192 ✗ av_log(s->avctx, AV_LOG_WARNING, "Invalid image height: %d, truncating.\n", height);
193 ✗ height = s->screen_height;
194 }
195
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 1294 if (top >= s->screen_height) {
196 ✗ av_log(s->avctx, AV_LOG_ERROR, "Invalid top position: %d.\n", top);
197 ✗ return AVERROR_INVALIDDATA;
198 }
199
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 1294 if (left + width > s->screen_width) {
200 /* width must be kept around to avoid lzw vs line desync */
201 ✗ pw = s->screen_width - left;
202 ✗ av_log(s->avctx, AV_LOG_WARNING, "Image too wide by %d, truncating.\n",
203 ✗ left + width - s->screen_width);
204 } else {
205 1294 pw = width;
206 }
207
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 1294 if (top + height > s->screen_height) {
208 /* we don't care about the extra invisible lines */
209 ✗ av_log(s->avctx, AV_LOG_WARNING, "Image too high by %d, truncating.\n",
210 ✗ top + height - s->screen_height);
211 ✗ height = s->screen_height - top;
212 }
213
214 /* process disposal method */
215
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 1294 if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) {
216 6 gif_fill_rect(frame, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h);
217
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 1288 } else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) {
218 1 gif_copy_img_rect(s->stored_img, (uint32_t *)frame->data[0],
219 1 frame->linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h);
220 }
221
222 1294 s->gce_prev_disposal = s->gce_disposal;
223
224
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 1294 if (s->gce_disposal != GCE_DISPOSAL_NONE) {
225 1293 s->gce_l = left; s->gce_t = top;
226 1293 s->gce_w = pw; s->gce_h = height;
227
228
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 1293 if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) {
229
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 8 if (s->transparent_color_index >= 0)
230 8 s->stored_bg_color = s->trans_color;
231 else
232 ✗ s->stored_bg_color = s->bg_color;
233
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 1285 } else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) {
234 2 av_fast_malloc(&s->stored_img, &s->stored_img_size, frame->linesize[0] * frame->height);
235
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 2 if (!s->stored_img)
236 ✗ return AVERROR(ENOMEM);
237
238 2 gif_copy_img_rect((uint32_t *)frame->data[0], s->stored_img,
239 2 frame->linesize[0] / sizeof(uint32_t), left, top, pw, height);
240 }
241 }
242
243 /* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */
244
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 1294 if (bytestream2_get_bytes_left(&s->gb) < 2)
245 ✗ return AVERROR_INVALIDDATA;
246
247 /* now get the image data */
248 1294 code_size = bytestream2_get_byteu(&s->gb);
249
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 1294 if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->gb.buffer,
250 bytestream2_get_bytes_left(&s->gb), FF_LZW_GIF)) < 0) {
251 ✗ av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n");
252 ✗ return ret;
253 }
254
255 /* read all the image */
256 1294 linesize = frame->linesize[0] / sizeof(uint32_t);
257 1294 ptr1 = (uint32_t *)frame->data[0] + top * linesize + left;
258 1294 ptr = ptr1;
259 1294 pass = 0;
260 1294 y1 = 0;
261
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 39267 for (y = 0; y < height; y++) {
262 37973 int count = ff_lzw_decode(s->lzw, s->idx_line, width);
263
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 37973 if (count != width) {
264 ✗ if (count)
265 ✗ av_log(s->avctx, AV_LOG_ERROR, "LZW decode failed\n");
266 ✗ goto decode_tail;
267 }
268
269 37973 pr = ptr + pw;
270
271
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 5366572 for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) {
272
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 5328599 if (*idx != s->transparent_color_index)
273 3988325 *px = pal[*idx];
274 }
275
276
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 37973 if (is_interleaved) {
277 ✗ switch(pass) {
278 ✗ default:
279 case 0:
280 case 1:
281 ✗ y1 += 8;
282 ✗ ptr += linesize * 8;
283 ✗ break;
284 ✗ case 2:
285 ✗ y1 += 4;
286 ✗ ptr += linesize * 4;
287 ✗ break;
288 ✗ case 3:
289 ✗ y1 += 2;
290 ✗ ptr += linesize * 2;
291 ✗ break;
292 }
293 ✗ while (y1 >= height) {
294 ✗ y1 = 4 >> pass;
295 ✗ ptr = ptr1 + linesize * y1;
296 ✗ pass++;
297 }
298 } else {
299 37973 ptr += linesize;
300 }
301 }
302
303 1294 decode_tail:
304 /* read the garbage data until end marker is found */
305 1294 lzwed_len = ff_lzw_decode_tail(s->lzw);
306 1294 bytestream2_skipu(&s->gb, lzwed_len);
307
308 /* Graphic Control Extension's scope is single frame.
309 * Remove its influence. */
310 1294 s->transparent_color_index = -1;
311 1294 s->gce_disposal = GCE_DISPOSAL_NONE;
312
313 1294 return 0;
314 }
315
316 1303 static int gif_read_extension(GifState *s)
317 {
318 int ext_code, ext_len, gce_flags, gce_transparent_index;
319
320 /* There must be at least 2 bytes:
321 * 1 for extension label and 1 for extension length. */
322
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 1303 if (bytestream2_get_bytes_left(&s->gb) < 2)
323 ✗ return AVERROR_INVALIDDATA;
324
325 1303 ext_code = bytestream2_get_byteu(&s->gb);
326 1303 ext_len = bytestream2_get_byteu(&s->gb);
327
328 ff_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
329
330
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 1303 switch(ext_code) {
331 1294 case GIF_GCE_EXT_LABEL:
332
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 1294 if (ext_len != 4)
333 ✗ goto discard_ext;
334
335 /* We need at least 5 bytes more: 4 is for extension body
336 * and 1 for next block size. */
337
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 1294 if (bytestream2_get_bytes_left(&s->gb) < 5)
338 ✗ return AVERROR_INVALIDDATA;
339
340 1294 gce_flags = bytestream2_get_byteu(&s->gb);
341 1294 bytestream2_skipu(&s->gb, 2); // delay during which the frame is shown
342 1294 gce_transparent_index = bytestream2_get_byteu(&s->gb);
343
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 1294 if (gce_flags & 0x01)
344 46 s->transparent_color_index = gce_transparent_index;
345 else
346 1248 s->transparent_color_index = -1;
347 1294 s->gce_disposal = (gce_flags >> 2) & 0x7;
348
349 ff_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n",
350 gce_flags,
351 s->transparent_color_index, s->gce_disposal);
352
353
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 1294 if (s->gce_disposal > 3) {
354 ✗ s->gce_disposal = GCE_DISPOSAL_NONE;
355 ff_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len);
356 }
357
358 1294 ext_len = bytestream2_get_byteu(&s->gb);
359 1294 break;
360 }
361
362 /* NOTE: many extension blocks can come after */
363 1303 discard_ext:
364
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 1330 while (ext_len) {
365 /* There must be at least ext_len bytes and 1 for next block size byte. */
366
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 27 if (bytestream2_get_bytes_left(&s->gb) < ext_len + 1)
367 ✗ return AVERROR_INVALIDDATA;
368
369 27 bytestream2_skipu(&s->gb, ext_len);
370 27 ext_len = bytestream2_get_byteu(&s->gb);
371
372 ff_dlog(s->avctx, "ext_len1=%d\n", ext_len);
373 }
374 1303 return 0;
375 }
376
377 13 static int gif_read_header1(GifState *s)
378 {
379 uint8_t sig[6];
380 int v, n;
381 int background_color_index;
382
383
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 13 if (bytestream2_get_bytes_left(&s->gb) < 13)
384 ✗ return AVERROR_INVALIDDATA;
385
386 /* read gif signature */
387 13 bytestream2_get_bufferu(&s->gb, sig, 6);
388
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 13 if (memcmp(sig, gif87a_sig, 6) &&
389
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 13 memcmp(sig, gif89a_sig, 6))
390 ✗ return AVERROR_INVALIDDATA;
391
392 /* read screen header */
393 13 s->transparent_color_index = -1;
394 13 s->screen_width = bytestream2_get_le16u(&s->gb);
395 13 s->screen_height = bytestream2_get_le16u(&s->gb);
396
397 13 v = bytestream2_get_byteu(&s->gb);
398 13 s->color_resolution = ((v & 0x70) >> 4) + 1;
399 13 s->has_global_palette = (v & 0x80);
400 13 s->bits_per_pixel = (v & 0x07) + 1;
401 13 background_color_index = bytestream2_get_byteu(&s->gb);
402 13 n = bytestream2_get_byteu(&s->gb);
403
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 13 if (n) {
404 ✗ s->avctx->sample_aspect_ratio.num = n + 15;
405 ✗ s->avctx->sample_aspect_ratio.den = 64;
406 }
407
408 ff_dlog(s->avctx, "screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
409 s->screen_width, s->screen_height, s->bits_per_pixel,
410 s->has_global_palette);
411
412
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 13 if (s->has_global_palette) {
413 6 s->background_color_index = background_color_index;
414 6 n = 1 << s->bits_per_pixel;
415
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 6 if (bytestream2_get_bytes_left(&s->gb) < n * 3)
416 ✗ return AVERROR_INVALIDDATA;
417
418 6 gif_read_palette(s, s->global_palette, n);
419 6 s->bg_color = s->global_palette[s->background_color_index];
420 } else
421 7 s->background_color_index = -1;
422
423 13 return 0;
424 }
425
426 1294 static int gif_parse_next_image(GifState *s, AVFrame *frame)
427 {
428
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 2597 while (bytestream2_get_bytes_left(&s->gb) > 0) {
429 2597 int code = bytestream2_get_byte(&s->gb);
430 int ret;
431
432 2597 av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code);
433
434
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 2597 switch (code) {
435 1294 case GIF_IMAGE_SEPARATOR:
436 1294 return gif_read_image(s, frame);
437 1303 case GIF_EXTENSION_INTRODUCER:
438
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 1303 if ((ret = gif_read_extension(s)) < 0)
439 ✗ return ret;
440 1303 break;
441 ✗ case GIF_TRAILER:
442 /* end of image */
443 ✗ return AVERROR_EOF;
444 ✗ default:
445 /* erroneous block label */
446 ✗ return AVERROR_INVALIDDATA;
447 }
448 }
449 ✗ return AVERROR_EOF;
450 }
451
452 28 static av_cold int gif_decode_init(AVCodecContext *avctx)
453 {
454 28 GifState *s = avctx->priv_data;
455
456 28 s->avctx = avctx;
457
458 28 avctx->pix_fmt = AV_PIX_FMT_RGB32;
459 28 s->frame = av_frame_alloc();
460
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 28 if (!s->frame)
461 ✗ return AVERROR(ENOMEM);
462 28 ff_lzw_decode_open(&s->lzw);
463
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 28 if (!s->lzw)
464 ✗ return AVERROR(ENOMEM);
465 28 return 0;
466 }
467
468 1294 static int gif_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
469 int *got_frame, AVPacket *avpkt)
470 {
471 1294 GifState *s = avctx->priv_data;
472 int ret;
473
474 1294 bytestream2_init(&s->gb, avpkt->data, avpkt->size);
475
476 1294 s->frame->pts = avpkt->pts;
477 1294 s->frame->pkt_dts = avpkt->dts;
478 1294 s->frame->pkt_duration = avpkt->duration;
479
480
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 1294 if (avpkt->size >= 6) {
481
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 2588 s->keyframe = memcmp(avpkt->data, gif87a_sig, 6) == 0 ||
482
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 1294 memcmp(avpkt->data, gif89a_sig, 6) == 0;
483 } else {
484 ✗ s->keyframe = 0;
485 }
486
487
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 1294 if (s->keyframe) {
488 13 s->keyframe_ok = 0;
489 13 s->gce_prev_disposal = GCE_DISPOSAL_NONE;
490
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 13 if ((ret = gif_read_header1(s)) < 0)
491 ✗ return ret;
492
493
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 13 if ((ret = ff_set_dimensions(avctx, s->screen_width, s->screen_height)) < 0)
494 ✗ return ret;
495
496 13 av_frame_unref(s->frame);
497
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 13 if ((ret = ff_get_buffer(avctx, s->frame, 0)) < 0)
498 ✗ return ret;
499
500 13 av_fast_malloc(&s->idx_line, &s->idx_line_size, s->screen_width);
501
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 13 if (!s->idx_line)
502 ✗ return AVERROR(ENOMEM);
503
504 13 s->frame->pict_type = AV_PICTURE_TYPE_I;
505 13 s->frame->key_frame = 1;
506 13 s->keyframe_ok = 1;
507 } else {
508
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 1281 if (!s->keyframe_ok) {
509 ✗ av_log(avctx, AV_LOG_ERROR, "cannot decode frame without keyframe\n");
510 ✗ return AVERROR_INVALIDDATA;
511 }
512
513
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 1281 if ((ret = ff_reget_buffer(avctx, s->frame, 0)) < 0)
514 ✗ return ret;
515
516 1281 s->frame->pict_type = AV_PICTURE_TYPE_P;
517 1281 s->frame->key_frame = 0;
518 }
519
520 1294 ret = gif_parse_next_image(s, s->frame);
521
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 1294 if (ret < 0)
522 ✗ return ret;
523
524
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 1294 if ((ret = av_frame_ref(rframe, s->frame)) < 0)
525 ✗ return ret;
526 1294 *got_frame = 1;
527
528 1294 return bytestream2_tell(&s->gb);
529 }
530
531 28 static av_cold int gif_decode_close(AVCodecContext *avctx)
532 {
533 28 GifState *s = avctx->priv_data;
534
535 28 ff_lzw_decode_close(&s->lzw);
536 28 av_frame_free(&s->frame);
537 28 av_freep(&s->idx_line);
538 28 av_freep(&s->stored_img);
539
540 28 return 0;
541 }
542
543 static const AVOption options[] = {
544 { "trans_color", "color value (ARGB) that is used instead of transparent color",
545 offsetof(GifState, trans_color), AV_OPT_TYPE_INT,
546 {.i64 = GIF_TRANSPARENT_COLOR}, 0, 0xffffffff,
547 AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM },
548 { NULL },
549 };
550
551 static const AVClass decoder_class = {
552 .class_name = "gif decoder",
553 .item_name = av_default_item_name,
554 .option = options,
555 .version = LIBAVUTIL_VERSION_INT,
556 .category = AV_CLASS_CATEGORY_DECODER,
557 };
558
559 const FFCodec ff_gif_decoder = {
560 .p.name = "gif",
561 .p.long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
562 .p.type = AVMEDIA_TYPE_VIDEO,
563 .p.id = AV_CODEC_ID_GIF,
564 .priv_data_size = sizeof(GifState),
565 .init = gif_decode_init,
566 .close = gif_decode_close,
567 FF_CODEC_DECODE_CB(gif_decode_frame),
568 .p.capabilities = AV_CODEC_CAP_DR1,
569 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE |
570 FF_CODEC_CAP_INIT_CLEANUP,
571 .p.priv_class = &decoder_class,
572 };
573