path: root/libavcodec/gifdec.c (plain)
blob: 48345db5459572b31e672c43b7482ca8525cbd97

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
38	typedef 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
79	static 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
87	static 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
96	static 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
112	static 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
130	static int gif_read_image(GifState *s, AVFrame *frame)
131	{
132	int left, top, width, height, bits_per_pixel, code_size, flags, pw;
133	int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size, lzwed_len;
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	ff_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 (!width || width > s->screen_width || left >= s->screen_width) {
183	av_log(s->avctx, AV_LOG_ERROR, "Invalid image width.\n");
184	return AVERROR_INVALIDDATA;
185	}
186	if (!height || height > s->screen_height || top >= s->screen_height) {
187	av_log(s->avctx, AV_LOG_ERROR, "Invalid image height.\n");
188	return AVERROR_INVALIDDATA;
189	}
190	if (left + width > s->screen_width) {
191	/* width must be kept around to avoid lzw vs line desync */
192	pw = s->screen_width - left;
193	av_log(s->avctx, AV_LOG_WARNING, "Image too wide by %d, truncating.\n",
194	left + width - s->screen_width);
195	} else {
196	pw = width;
197	}
198	if (top + height > s->screen_height) {
199	/* we don't care about the extra invisible lines */
200	av_log(s->avctx, AV_LOG_WARNING, "Image too high by %d, truncating.\n",
201	top + height - s->screen_height);
202	height = s->screen_height - top;
203	}
204
205	/* process disposal method */
206	if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) {
207	gif_fill_rect(frame, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h);
208	} else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) {
209	gif_copy_img_rect(s->stored_img, (uint32_t *)frame->data[0],
210	frame->linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h);
211	}
212
213	s->gce_prev_disposal = s->gce_disposal;
214
215	if (s->gce_disposal != GCE_DISPOSAL_NONE) {
216	s->gce_l = left; s->gce_t = top;
217	s->gce_w = pw; s->gce_h = height;
218
219	if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) {
220	if (s->transparent_color_index >= 0)
221	s->stored_bg_color = s->trans_color;
222	else
223	s->stored_bg_color = s->bg_color;
224	} else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) {
225	av_fast_malloc(&s->stored_img, &s->stored_img_size, frame->linesize[0] * frame->height);
226	if (!s->stored_img)
227	return AVERROR(ENOMEM);
228
229	gif_copy_img_rect((uint32_t *)frame->data[0], s->stored_img,
230	frame->linesize[0] / sizeof(uint32_t), left, top, pw, height);
231	}
232	}
233
234	/* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */
235	if (bytestream2_get_bytes_left(&s->gb) < 2)
236	return AVERROR_INVALIDDATA;
237
238	/* now get the image data */
239	code_size = bytestream2_get_byteu(&s->gb);
240	if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->gb.buffer,
241	bytestream2_get_bytes_left(&s->gb), FF_LZW_GIF)) < 0) {
242	av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n");
243	return ret;
244	}
245
246	/* read all the image */
247	linesize = frame->linesize[0] / sizeof(uint32_t);
248	ptr1 = (uint32_t *)frame->data[0] + top * linesize + left;
249	ptr = ptr1;
250	pass = 0;
251	y1 = 0;
252	for (y = 0; y < height; y++) {
253	int count = ff_lzw_decode(s->lzw, s->idx_line, width);
254	if (count != width) {
255	if (count)
256	av_log(s->avctx, AV_LOG_ERROR, "LZW decode failed\n");
257	goto decode_tail;
258	}
259
260	pr = ptr + pw;
261
262	for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) {
263	if (*idx != s->transparent_color_index)
264	*px = pal[*idx];
265	}
266
267	if (is_interleaved) {
268	switch(pass) {
269	default:
270	case 0:
271	case 1:
272	y1 += 8;
273	ptr += linesize * 8;
274	break;
275	case 2:
276	y1 += 4;
277	ptr += linesize * 4;
278	break;
279	case 3:
280	y1 += 2;
281	ptr += linesize * 2;
282	break;
283	}
284	while (y1 >= height) {
285	y1 = 4 >> pass;
286	ptr = ptr1 + linesize * y1;
287	pass++;
288	}
289	} else {
290	ptr += linesize;
291	}
292	}
293
294	decode_tail:
295	/* read the garbage data until end marker is found */
296	lzwed_len = ff_lzw_decode_tail(s->lzw);
297	bytestream2_skipu(&s->gb, lzwed_len);
298
299	/* Graphic Control Extension's scope is single frame.
300	* Remove its influence. */
301	s->transparent_color_index = -1;
302	s->gce_disposal = GCE_DISPOSAL_NONE;
303
304	return 0;
305	}
306
307	static int gif_read_extension(GifState *s)
308	{
309	int ext_code, ext_len, gce_flags, gce_transparent_index;
310
311	/* There must be at least 2 bytes:
312	* 1 for extension label and 1 for extension length. */
313	if (bytestream2_get_bytes_left(&s->gb) < 2)
314	return AVERROR_INVALIDDATA;
315
316	ext_code = bytestream2_get_byteu(&s->gb);
317	ext_len = bytestream2_get_byteu(&s->gb);
318
319	ff_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
320
321	switch(ext_code) {
322	case GIF_GCE_EXT_LABEL:
323	if (ext_len != 4)
324	goto discard_ext;
325
326	/* We need at least 5 bytes more: 4 is for extension body
327	* and 1 for next block size. */
328	if (bytestream2_get_bytes_left(&s->gb) < 5)
329	return AVERROR_INVALIDDATA;
330
331	gce_flags = bytestream2_get_byteu(&s->gb);
332	bytestream2_skipu(&s->gb, 2); // delay during which the frame is shown
333	gce_transparent_index = bytestream2_get_byteu(&s->gb);
334	if (gce_flags & 0x01)
335	s->transparent_color_index = gce_transparent_index;
336	else
337	s->transparent_color_index = -1;
338	s->gce_disposal = (gce_flags >> 2) & 0x7;
339
340	ff_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n",
341	gce_flags,
342	s->transparent_color_index, s->gce_disposal);
343
344	if (s->gce_disposal > 3) {
345	s->gce_disposal = GCE_DISPOSAL_NONE;
346	ff_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len);
347	}
348
349	ext_len = bytestream2_get_byteu(&s->gb);
350	break;
351	}
352
353	/* NOTE: many extension blocks can come after */
354	discard_ext:
355	while (ext_len) {
356	/* There must be at least ext_len bytes and 1 for next block size byte. */
357	if (bytestream2_get_bytes_left(&s->gb) < ext_len + 1)
358	return AVERROR_INVALIDDATA;
359
360	bytestream2_skipu(&s->gb, ext_len);
361	ext_len = bytestream2_get_byteu(&s->gb);
362
363	ff_dlog(s->avctx, "ext_len1=%d\n", ext_len);
364	}
365	return 0;
366	}
367
368	static int gif_read_header1(GifState *s)
369	{
370	uint8_t sig[6];
371	int v, n;
372	int background_color_index;
373
374	if (bytestream2_get_bytes_left(&s->gb) < 13)
375	return AVERROR_INVALIDDATA;
376
377	/* read gif signature */
378	bytestream2_get_bufferu(&s->gb, sig, 6);
379	if (memcmp(sig, gif87a_sig, 6) &&
380	memcmp(sig, gif89a_sig, 6))
381	return AVERROR_INVALIDDATA;
382
383	/* read screen header */
384	s->transparent_color_index = -1;
385	s->screen_width = bytestream2_get_le16u(&s->gb);
386	s->screen_height = bytestream2_get_le16u(&s->gb);
387
388	v = bytestream2_get_byteu(&s->gb);
389	s->color_resolution = ((v & 0x70) >> 4) + 1;
390	s->has_global_palette = (v & 0x80);
391	s->bits_per_pixel = (v & 0x07) + 1;
392	background_color_index = bytestream2_get_byteu(&s->gb);
393	n = bytestream2_get_byteu(&s->gb);
394	if (n) {
395	s->avctx->sample_aspect_ratio.num = n + 15;
396	s->avctx->sample_aspect_ratio.den = 64;
397	}
398
399	ff_dlog(s->avctx, "screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
400	s->screen_width, s->screen_height, s->bits_per_pixel,
401	s->has_global_palette);
402
403	if (s->has_global_palette) {
404	s->background_color_index = background_color_index;
405	n = 1 << s->bits_per_pixel;
406	if (bytestream2_get_bytes_left(&s->gb) < n * 3)
407	return AVERROR_INVALIDDATA;
408
409	gif_read_palette(s, s->global_palette, n);
410	s->bg_color = s->global_palette[s->background_color_index];
411	} else
412	s->background_color_index = -1;
413
414	return 0;
415	}
416
417	static int gif_parse_next_image(GifState *s, AVFrame *frame)
418	{
419	while (bytestream2_get_bytes_left(&s->gb) > 0) {
420	int code = bytestream2_get_byte(&s->gb);
421	int ret;
422
423	av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code);
424
425	switch (code) {
426	case GIF_IMAGE_SEPARATOR:
427	return gif_read_image(s, frame);
428	case GIF_EXTENSION_INTRODUCER:
429	if ((ret = gif_read_extension(s)) < 0)
430	return ret;
431	break;
432	case GIF_TRAILER:
433	/* end of image */
434	return AVERROR_EOF;
435	default:
436	/* erroneous block label */
437	return AVERROR_INVALIDDATA;
438	}
439	}
440	return AVERROR_EOF;
441	}
442
443	static av_cold int gif_decode_init(AVCodecContext *avctx)
444	{
445	GifState *s = avctx->priv_data;
446
447	s->avctx = avctx;
448
449	avctx->pix_fmt = AV_PIX_FMT_RGB32;
450	s->frame = av_frame_alloc();
451	if (!s->frame)
452	return AVERROR(ENOMEM);
453	ff_lzw_decode_open(&s->lzw);
454	return 0;
455	}
456
457	static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
458	{
459	GifState *s = avctx->priv_data;
460	int ret;
461
462	bytestream2_init(&s->gb, avpkt->data, avpkt->size);
463
464	s->frame->pts = avpkt->pts;
465	#if FF_API_PKT_PTS
466	FF_DISABLE_DEPRECATION_WARNINGS
467	s->frame->pkt_pts = avpkt->pts;
468	FF_ENABLE_DEPRECATION_WARNINGS
469	#endif
470	s->frame->pkt_dts = avpkt->dts;
471	av_frame_set_pkt_duration(s->frame, avpkt->duration);
472
473	if (avpkt->size >= 6) {
474	s->keyframe = memcmp(avpkt->data, gif87a_sig, 6) == 0 ||
475	memcmp(avpkt->data, gif89a_sig, 6) == 0;
476	} else {
477	s->keyframe = 0;
478	}
479
480	if (s->keyframe) {
481	s->keyframe_ok = 0;
482	s->gce_prev_disposal = GCE_DISPOSAL_NONE;
483	if ((ret = gif_read_header1(s)) < 0)
484	return ret;
485
486	if ((ret = ff_set_dimensions(avctx, s->screen_width, s->screen_height)) < 0)
487	return ret;
488
489	av_frame_unref(s->frame);
490	if ((ret = ff_get_buffer(avctx, s->frame, 0)) < 0)
491	return ret;
492
493	av_fast_malloc(&s->idx_line, &s->idx_line_size, s->screen_width);
494	if (!s->idx_line)
495	return AVERROR(ENOMEM);
496
497	s->frame->pict_type = AV_PICTURE_TYPE_I;
498	s->frame->key_frame = 1;
499	s->keyframe_ok = 1;
500	} else {
501	if (!s->keyframe_ok) {
502	av_log(avctx, AV_LOG_ERROR, "cannot decode frame without keyframe\n");
503	return AVERROR_INVALIDDATA;
504	}
505
506	if ((ret = ff_reget_buffer(avctx, s->frame)) < 0)
507	return ret;
508
509	s->frame->pict_type = AV_PICTURE_TYPE_P;
510	s->frame->key_frame = 0;
511	}
512
513	ret = gif_parse_next_image(s, s->frame);
514	if (ret < 0)
515	return ret;
516
517	if ((ret = av_frame_ref(data, s->frame)) < 0)
518	return ret;
519	*got_frame = 1;
520
521	return bytestream2_tell(&s->gb);
522	}
523
524	static av_cold int gif_decode_close(AVCodecContext *avctx)
525	{
526	GifState *s = avctx->priv_data;
527
528	ff_lzw_decode_close(&s->lzw);
529	av_frame_free(&s->frame);
530	av_freep(&s->idx_line);
531	av_freep(&s->stored_img);
532
533	return 0;
534	}
535
536	static const AVOption options[] = {
537	{ "trans_color", "color value (ARGB) that is used instead of transparent color",
538	offsetof(GifState, trans_color), AV_OPT_TYPE_INT,
539	{.i64 = GIF_TRANSPARENT_COLOR}, 0, 0xffffffff,
540	AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM },
541	{ NULL },
542	};
543
544	static const AVClass decoder_class = {
545	.class_name = "gif decoder",
546	.item_name = av_default_item_name,
547	.option = options,
548	.version = LIBAVUTIL_VERSION_INT,
549	.category = AV_CLASS_CATEGORY_DECODER,
550	};
551
552	AVCodec ff_gif_decoder = {
553	.name = "gif",
554	.long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
555	.type = AVMEDIA_TYPE_VIDEO,
556	.id = AV_CODEC_ID_GIF,
557	.priv_data_size = sizeof(GifState),
558	.init = gif_decode_init,
559	.close = gif_decode_close,
560	.decode = gif_decode_frame,
561	.capabilities = AV_CODEC_CAP_DR1,
562	.priv_class = &decoder_class,
563	};
564