3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2006 Baptiste Coudurier
5 * Copyright (c) 2012 Vitaliy E Sugrobov
7 * This file is part of FFmpeg.
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.
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.
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
24 #include "libavutil/imgutils.h"
25 #include "libavutil/opt.h"
27 #include "bytestream.h"
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.
36 #define GIF_TRANSPARENT_COLOR 0x00ffffff
38 typedef struct GifState {
43 int has_global_palette;
46 int background_color_index;
47 int transparent_color_index;
49 /* intermediate buffer for storing color indices
50 * obtained from lzw-encoded data stream */
54 /* after the frame is displayed, the disposal method is used */
55 int gce_prev_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;
67 /* LZW compatible decoder */
71 uint32_t global_palette[256];
72 uint32_t local_palette[256];
74 AVCodecContext *avctx;
77 int trans_color; /**< color value that is used instead of transparent color */
80 static void gif_read_palette(GifState *s, uint32_t *pal, int nb)
84 for (i = 0; i < nb; i++, pal++)
85 *pal = (0xffu << 24) | bytestream2_get_be24u(&s->gb);
88 static void gif_fill(AVFrame *picture, uint32_t color)
90 uint32_t *p = (uint32_t *)picture->data[0];
91 uint32_t *p_end = p + (picture->linesize[0] / sizeof(uint32_t)) * picture->height;
93 for (; p < p_end; p++)
97 static void gif_fill_rect(AVFrame *picture, uint32_t color, int l, int t, int w, int h)
99 const int linesize = picture->linesize[0] / sizeof(uint32_t);
100 const uint32_t *py = (uint32_t *)picture->data[0] + t * linesize;
101 const uint32_t *pr, *pb = py + h * linesize;
104 for (; py < pb; py += linesize) {
105 px = (uint32_t *)py + l;
108 for (; px < pr; px++)
113 static void gif_copy_img_rect(const uint32_t *src, uint32_t *dst,
114 int linesize, int l, int t, int w, int h)
116 const int y_start = t * linesize;
117 const uint32_t *src_px,
118 *src_py = src + y_start,
119 *dst_py = dst + y_start;
120 const uint32_t *src_pb = src_py + h * linesize;
123 for (; src_py < src_pb; src_py += linesize, dst_py += linesize) {
125 dst_px = (uint32_t *)dst_py + l;
127 memcpy(dst_px, src_px, w * sizeof(uint32_t));
131 static int gif_read_image(GifState *s, AVFrame *frame)
133 int left, top, width, height, bits_per_pixel, code_size, flags;
134 int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size;
135 uint32_t *ptr, *pal, *px, *pr, *ptr1;
139 /* At least 9 bytes of Image Descriptor. */
140 if (bytestream2_get_bytes_left(&s->gb) < 9)
141 return AVERROR_INVALIDDATA;
143 left = bytestream2_get_le16u(&s->gb);
144 top = bytestream2_get_le16u(&s->gb);
145 width = bytestream2_get_le16u(&s->gb);
146 height = bytestream2_get_le16u(&s->gb);
147 flags = bytestream2_get_byteu(&s->gb);
148 is_interleaved = flags & 0x40;
149 has_local_palette = flags & 0x80;
150 bits_per_pixel = (flags & 0x07) + 1;
152 av_dlog(s->avctx, "image x=%d y=%d w=%d h=%d\n", left, top, width, height);
154 if (has_local_palette) {
155 pal_size = 1 << bits_per_pixel;
157 if (bytestream2_get_bytes_left(&s->gb) < pal_size * 3)
158 return AVERROR_INVALIDDATA;
160 gif_read_palette(s, s->local_palette, pal_size);
161 pal = s->local_palette;
163 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;
168 pal = s->global_palette;
172 if (s->transparent_color_index == -1 && s->has_global_palette) {
173 /* transparency wasn't set before the first frame, fill with background color */
174 gif_fill(frame, s->bg_color);
176 /* otherwise fill with transparent color.
177 * this is necessary since by default picture filled with 0x80808080. */
178 gif_fill(frame, s->trans_color);
182 /* verify that all the image is inside the screen dimensions */
183 if (left + width > s->screen_width ||
184 top + height > s->screen_height)
185 return AVERROR_INVALIDDATA;
186 if (width <= 0 || height <= 0)
187 return AVERROR_INVALIDDATA;
189 /* process disposal method */
190 if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) {
191 gif_fill_rect(frame, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h);
192 } else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) {
193 gif_copy_img_rect(s->stored_img, (uint32_t *)frame->data[0],
194 frame->linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h);
197 s->gce_prev_disposal = s->gce_disposal;
199 if (s->gce_disposal != GCE_DISPOSAL_NONE) {
200 s->gce_l = left; s->gce_t = top;
201 s->gce_w = width; s->gce_h = height;
203 if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) {
204 if (s->transparent_color_index >= 0)
205 s->stored_bg_color = s->trans_color;
207 s->stored_bg_color = s->bg_color;
208 } else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) {
209 av_fast_malloc(&s->stored_img, &s->stored_img_size, frame->linesize[0] * frame->height);
211 return AVERROR(ENOMEM);
213 gif_copy_img_rect((uint32_t *)frame->data[0], s->stored_img,
214 frame->linesize[0] / sizeof(uint32_t), left, top, width, height);
218 /* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */
219 if (bytestream2_get_bytes_left(&s->gb) < 2)
220 return AVERROR_INVALIDDATA;
222 /* now get the image data */
223 code_size = bytestream2_get_byteu(&s->gb);
224 if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->gb.buffer,
225 bytestream2_get_bytes_left(&s->gb), FF_LZW_GIF)) < 0) {
226 av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n");
230 /* read all the image */
231 linesize = frame->linesize[0] / sizeof(uint32_t);
232 ptr1 = (uint32_t *)frame->data[0] + top * linesize + left;
236 for (y = 0; y < height; y++) {
237 if (ff_lzw_decode(s->lzw, s->idx_line, width) == 0)
242 for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) {
243 if (*idx != s->transparent_color_index)
247 if (is_interleaved) {
256 ptr = ptr1 + linesize * y1;
265 ptr = ptr1 + linesize;
280 /* read the garbage data until end marker is found */
281 ff_lzw_decode_tail(s->lzw);
283 /* Graphic Control Extension's scope is single frame.
284 * Remove its influence. */
285 s->transparent_color_index = -1;
286 s->gce_disposal = GCE_DISPOSAL_NONE;
291 static int gif_read_extension(GifState *s)
293 int ext_code, ext_len, gce_flags, gce_transparent_index;
295 /* There must be at least 2 bytes:
296 * 1 for extension label and 1 for extension length. */
297 if (bytestream2_get_bytes_left(&s->gb) < 2)
298 return AVERROR_INVALIDDATA;
300 ext_code = bytestream2_get_byteu(&s->gb);
301 ext_len = bytestream2_get_byteu(&s->gb);
303 av_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
306 case GIF_GCE_EXT_LABEL:
310 /* We need at least 5 bytes more: 4 is for extension body
311 * and 1 for next block size. */
312 if (bytestream2_get_bytes_left(&s->gb) < 5)
313 return AVERROR_INVALIDDATA;
315 gce_flags = bytestream2_get_byteu(&s->gb);
316 bytestream2_skipu(&s->gb, 2); // delay during which the frame is shown
317 gce_transparent_index = bytestream2_get_byteu(&s->gb);
318 if (gce_flags & 0x01)
319 s->transparent_color_index = gce_transparent_index;
321 s->transparent_color_index = -1;
322 s->gce_disposal = (gce_flags >> 2) & 0x7;
324 av_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n",
326 s->transparent_color_index, s->gce_disposal);
328 if (s->gce_disposal > 3) {
329 s->gce_disposal = GCE_DISPOSAL_NONE;
330 av_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len);
333 ext_len = bytestream2_get_byteu(&s->gb);
337 /* NOTE: many extension blocks can come after */
340 /* There must be at least ext_len bytes and 1 for next block size byte. */
341 if (bytestream2_get_bytes_left(&s->gb) < ext_len + 1)
342 return AVERROR_INVALIDDATA;
344 bytestream2_skipu(&s->gb, ext_len);
345 ext_len = bytestream2_get_byteu(&s->gb);
347 av_dlog(s->avctx, "ext_len1=%d\n", ext_len);
352 static int gif_read_header1(GifState *s)
356 int background_color_index;
358 if (bytestream2_get_bytes_left(&s->gb) < 13)
359 return AVERROR_INVALIDDATA;
361 /* read gif signature */
362 bytestream2_get_bufferu(&s->gb, sig, 6);
363 if (memcmp(sig, gif87a_sig, 6) &&
364 memcmp(sig, gif89a_sig, 6))
365 return AVERROR_INVALIDDATA;
367 /* read screen header */
368 s->transparent_color_index = -1;
369 s->screen_width = bytestream2_get_le16u(&s->gb);
370 s->screen_height = bytestream2_get_le16u(&s->gb);
372 v = bytestream2_get_byteu(&s->gb);
373 s->color_resolution = ((v & 0x70) >> 4) + 1;
374 s->has_global_palette = (v & 0x80);
375 s->bits_per_pixel = (v & 0x07) + 1;
376 background_color_index = bytestream2_get_byteu(&s->gb);
377 n = bytestream2_get_byteu(&s->gb);
379 s->avctx->sample_aspect_ratio.num = n + 15;
380 s->avctx->sample_aspect_ratio.den = 64;
383 av_dlog(s->avctx, "screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
384 s->screen_width, s->screen_height, s->bits_per_pixel,
385 s->has_global_palette);
387 if (s->has_global_palette) {
388 s->background_color_index = background_color_index;
389 n = 1 << s->bits_per_pixel;
390 if (bytestream2_get_bytes_left(&s->gb) < n * 3)
391 return AVERROR_INVALIDDATA;
393 gif_read_palette(s, s->global_palette, n);
394 s->bg_color = s->global_palette[s->background_color_index];
396 s->background_color_index = -1;
401 static int gif_parse_next_image(GifState *s, AVFrame *frame)
403 while (bytestream2_get_bytes_left(&s->gb)) {
404 int code = bytestream2_get_byte(&s->gb);
407 av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code);
410 case GIF_IMAGE_SEPARATOR:
411 return gif_read_image(s, frame);
412 case GIF_EXTENSION_INTRODUCER:
413 if ((ret = gif_read_extension(s)) < 0)
420 /* erroneous block label */
421 return AVERROR_INVALIDDATA;
427 static av_cold int gif_decode_init(AVCodecContext *avctx)
429 GifState *s = avctx->priv_data;
433 avctx->pix_fmt = AV_PIX_FMT_RGB32;
434 s->frame = av_frame_alloc();
436 return AVERROR(ENOMEM);
437 ff_lzw_decode_open(&s->lzw);
441 static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
443 GifState *s = avctx->priv_data;
446 bytestream2_init(&s->gb, avpkt->data, avpkt->size);
448 s->frame->pts = avpkt->pts;
449 s->frame->pkt_pts = avpkt->pts;
450 s->frame->pkt_dts = avpkt->dts;
451 av_frame_set_pkt_duration(s->frame, avpkt->duration);
453 if (avpkt->size >= 6) {
454 s->keyframe = memcmp(avpkt->data, gif87a_sig, 6) == 0 ||
455 memcmp(avpkt->data, gif89a_sig, 6) == 0;
462 s->gce_prev_disposal = GCE_DISPOSAL_NONE;
463 if ((ret = gif_read_header1(s)) < 0)
466 if ((ret = av_image_check_size(s->screen_width, s->screen_height, 0, avctx)) < 0)
468 avcodec_set_dimensions(avctx, s->screen_width, s->screen_height);
470 av_frame_unref(s->frame);
471 if ((ret = ff_get_buffer(avctx, s->frame, 0)) < 0)
474 av_fast_malloc(&s->idx_line, &s->idx_line_size, s->screen_width);
476 return AVERROR(ENOMEM);
478 s->frame->pict_type = AV_PICTURE_TYPE_I;
479 s->frame->key_frame = 1;
482 if (!s->keyframe_ok) {
483 av_log(avctx, AV_LOG_ERROR, "cannot decode frame without keyframe\n");
484 return AVERROR_INVALIDDATA;
487 if ((ret = ff_reget_buffer(avctx, s->frame)) < 0)
490 s->frame->pict_type = AV_PICTURE_TYPE_P;
491 s->frame->key_frame = 0;
494 ret = gif_parse_next_image(s, s->frame);
498 if ((ret = av_frame_ref(data, s->frame)) < 0)
505 static av_cold int gif_decode_close(AVCodecContext *avctx)
507 GifState *s = avctx->priv_data;
509 ff_lzw_decode_close(&s->lzw);
510 av_frame_free(&s->frame);
511 av_freep(&s->idx_line);
512 av_freep(&s->stored_img);
517 static const AVOption options[] = {
518 { "trans_color", "color value (ARGB) that is used instead of transparent color",
519 offsetof(GifState, trans_color), AV_OPT_TYPE_INT,
520 {.i64 = GIF_TRANSPARENT_COLOR}, 0, 0xffffffff,
521 AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM },
525 static const AVClass decoder_class = {
526 .class_name = "gif decoder",
527 .item_name = av_default_item_name,
529 .version = LIBAVUTIL_VERSION_INT,
530 .category = AV_CLASS_CATEGORY_DECODER,
533 AVCodec ff_gif_decoder = {
535 .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
536 .type = AVMEDIA_TYPE_VIDEO,
537 .id = AV_CODEC_ID_GIF,
538 .priv_data_size = sizeof(GifState),
539 .init = gif_decode_init,
540 .close = gif_decode_close,
541 .decode = gif_decode_frame,
542 .capabilities = CODEC_CAP_DR1,
543 .priv_class = &decoder_class,