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
26 #include "libavutil/imgutils.h"
27 #include "libavutil/opt.h"
29 #include "bytestream.h"
34 /* This value is intentionally set to "transparent white" color.
35 * It is much better to have white background instead of black
36 * when gif image converted to format which not support transparency.
38 #define GIF_TRANSPARENT_COLOR 0x00ffffff
40 typedef struct GifState {
45 int has_global_palette;
48 int background_color_index;
49 int transparent_color_index;
51 /* intermediate buffer for storing color indices
52 * obtained from lzw-encoded data stream */
56 /* after the frame is displayed, the disposal method is used */
57 int gce_prev_disposal;
59 /* rectangle describing area that must be disposed */
60 int gce_l, gce_t, gce_w, gce_h;
61 /* depending on disposal method we store either part of the image
62 * drawn on the canvas or background color that
63 * should be used upon disposal */
64 uint32_t * stored_img;
68 /* LZW compatible decoder */
69 const uint8_t *bytestream;
70 const uint8_t *bytestream_end;
74 uint32_t global_palette[256];
75 uint32_t local_palette[256];
77 AVCodecContext *avctx;
79 int trans_color; /**< color value that is used instead of transparent color */
82 static void gif_read_palette(const uint8_t **buf, uint32_t *pal, int nb)
84 const uint8_t *pal_end = *buf + nb * 3;
86 for (; *buf < pal_end; *buf += 3, pal++)
87 *pal = (0xffu << 24) | AV_RB24(*buf);
90 static void gif_fill(AVFrame *picture, uint32_t color)
92 uint32_t *p = (uint32_t *)picture->data[0];
93 uint32_t *p_end = p + (picture->linesize[0] / sizeof(uint32_t)) * picture->height;
95 for (; p < p_end; p++)
99 static void gif_fill_rect(AVFrame *picture, uint32_t color, int l, int t, int w, int h)
101 const int linesize = picture->linesize[0] / sizeof(uint32_t);
102 const uint32_t *py = (uint32_t *)picture->data[0] + t * linesize;
103 const uint32_t *pr, *pb = py + (t + h) * linesize;
106 for (; py < pb; py += linesize) {
107 px = (uint32_t *)py + l;
110 for (; px < pr; px++)
115 static void gif_copy_img_rect(const uint32_t *src, uint32_t *dst,
116 int linesize, int l, int t, int w, int h)
118 const int y_start = t * linesize;
119 const uint32_t *src_px, *src_pr,
120 *src_py = src + y_start,
121 *dst_py = dst + y_start;
122 const uint32_t *src_pb = src_py + (t + h) * linesize;
125 for (; src_py < src_pb; src_py += linesize, dst_py += linesize) {
127 dst_px = (uint32_t *)dst_py + l;
130 for (; src_px < src_pr; src_px++, dst_px++)
135 static int gif_read_image(GifState *s)
137 int left, top, width, height, bits_per_pixel, code_size, flags;
138 int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size;
139 uint32_t *ptr, *pal, *px, *pr, *ptr1;
143 /* At least 9 bytes of Image Descriptor. */
144 if (s->bytestream_end < s->bytestream + 9)
145 return AVERROR_INVALIDDATA;
147 left = bytestream_get_le16(&s->bytestream);
148 top = bytestream_get_le16(&s->bytestream);
149 width = bytestream_get_le16(&s->bytestream);
150 height = bytestream_get_le16(&s->bytestream);
151 flags = bytestream_get_byte(&s->bytestream);
152 is_interleaved = flags & 0x40;
153 has_local_palette = flags & 0x80;
154 bits_per_pixel = (flags & 0x07) + 1;
156 av_dlog(s->avctx, "image x=%d y=%d w=%d h=%d\n", left, top, width, height);
158 if (has_local_palette) {
159 pal_size = 1 << bits_per_pixel;
161 if (s->bytestream_end < s->bytestream + pal_size * 3)
162 return AVERROR_INVALIDDATA;
164 gif_read_palette(&s->bytestream, s->local_palette, pal_size);
165 pal = s->local_palette;
167 if (!s->has_global_palette) {
168 av_log(s->avctx, AV_LOG_FATAL, "picture doesn't have either global or local palette.\n");
169 return AVERROR_INVALIDDATA;
172 pal = s->global_palette;
176 if (s->transparent_color_index == -1 && s->has_global_palette) {
177 /* transparency wasn't set before the first frame, fill with background color */
178 gif_fill(&s->picture, s->bg_color);
180 /* otherwise fill with transparent color.
181 * this is necessary since by default picture filled with 0x80808080. */
182 gif_fill(&s->picture, s->trans_color);
186 /* verify that all the image is inside the screen dimensions */
187 if (left + width > s->screen_width ||
188 top + height > s->screen_height)
189 return AVERROR(EINVAL);
191 /* process disposal method */
192 if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) {
193 gif_fill_rect(&s->picture, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h);
194 } else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) {
195 gif_copy_img_rect(s->stored_img, (uint32_t *)s->picture.data[0],
196 s->picture.linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h);
199 s->gce_prev_disposal = s->gce_disposal;
201 if (s->gce_disposal != GCE_DISPOSAL_NONE) {
202 s->gce_l = left; s->gce_t = top;
203 s->gce_w = width; s->gce_h = height;
205 if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) {
206 if (s->background_color_index == s->transparent_color_index)
207 s->stored_bg_color = s->trans_color;
209 s->stored_bg_color = s->bg_color;
210 } else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) {
211 av_fast_malloc(&s->stored_img, &s->stored_img_size, s->picture.linesize[0] * s->picture.height);
213 return AVERROR(ENOMEM);
215 gif_copy_img_rect((uint32_t *)s->picture.data[0], s->stored_img,
216 s->picture.linesize[0] / sizeof(uint32_t), left, top, width, height);
220 /* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */
221 if (s->bytestream_end < s->bytestream + 2)
222 return AVERROR_INVALIDDATA;
224 /* now get the image data */
225 code_size = bytestream_get_byte(&s->bytestream);
226 if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->bytestream,
227 s->bytestream_end - s->bytestream, FF_LZW_GIF)) < 0) {
228 av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n");
232 /* read all the image */
233 linesize = s->picture.linesize[0] / sizeof(uint32_t);
234 ptr1 = (uint32_t *)s->picture.data[0] + top * linesize + left;
238 for (y = 0; y < height; y++) {
239 if (ff_lzw_decode(s->lzw, s->idx_line, width) == 0)
244 for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) {
245 if (*idx != s->transparent_color_index)
249 if (is_interleaved) {
258 ptr = ptr1 + linesize * y1;
267 ptr = ptr1 + linesize;
282 /* read the garbage data until end marker is found */
283 ff_lzw_decode_tail(s->lzw);
284 s->bytestream = ff_lzw_cur_ptr(s->lzw);
286 /* Graphic Control Extension's scope is single frame.
287 * Remove its influence. */
288 s->transparent_color_index = -1;
289 s->gce_disposal = GCE_DISPOSAL_NONE;
294 static int gif_read_extension(GifState *s)
296 int ext_code, ext_len, i, gce_flags, gce_transparent_index;
298 /* There must be at least 2 bytes:
299 * 1 for extension label and 1 for extension length. */
300 if (s->bytestream_end < s->bytestream + 2)
301 return AVERROR_INVALIDDATA;
303 ext_code = bytestream_get_byte(&s->bytestream);
304 ext_len = bytestream_get_byte(&s->bytestream);
306 av_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
309 case GIF_GCE_EXT_LABEL:
313 /* We need at least 5 bytes more: 4 is for extension body
314 * and 1 for next block size. */
315 if (s->bytestream_end < s->bytestream + 5)
316 return AVERROR_INVALIDDATA;
318 s->transparent_color_index = -1;
319 gce_flags = bytestream_get_byte(&s->bytestream);
320 bytestream_get_le16(&s->bytestream); // delay during which the frame is shown
321 gce_transparent_index = bytestream_get_byte(&s->bytestream);
322 if (gce_flags & 0x01)
323 s->transparent_color_index = gce_transparent_index;
325 s->transparent_color_index = -1;
326 s->gce_disposal = (gce_flags >> 2) & 0x7;
328 av_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n",
330 s->transparent_color_index, s->gce_disposal);
332 if (s->gce_disposal > 3) {
333 s->gce_disposal = GCE_DISPOSAL_NONE;
334 av_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len);
337 ext_len = bytestream_get_byte(&s->bytestream);
341 /* NOTE: many extension blocks can come after */
343 while (ext_len != 0) {
344 /* There must be at least ext_len bytes and 1 for next block size byte. */
345 if (s->bytestream_end < s->bytestream + ext_len + 1)
346 return AVERROR_INVALIDDATA;
348 for (i = 0; i < ext_len; i++)
349 bytestream_get_byte(&s->bytestream);
350 ext_len = bytestream_get_byte(&s->bytestream);
352 av_dlog(s->avctx, "ext_len1=%d\n", ext_len);
357 static int gif_read_header1(GifState *s)
361 int background_color_index;
363 if (s->bytestream_end < s->bytestream + 13)
364 return AVERROR_INVALIDDATA;
366 /* read gif signature */
367 bytestream_get_buffer(&s->bytestream, sig, 6);
368 if (memcmp(sig, gif87a_sig, 6) != 0 &&
369 memcmp(sig, gif89a_sig, 6) != 0)
370 return AVERROR_INVALIDDATA;
372 /* read screen header */
373 s->transparent_color_index = -1;
374 s->screen_width = bytestream_get_le16(&s->bytestream);
375 s->screen_height = bytestream_get_le16(&s->bytestream);
376 if( (unsigned)s->screen_width > 32767
377 || (unsigned)s->screen_height > 32767){
378 av_log(s->avctx, AV_LOG_ERROR, "picture size too large\n");
379 return AVERROR_INVALIDDATA;
382 av_fast_malloc(&s->idx_line, &s->idx_line_size, s->screen_width);
384 return AVERROR(ENOMEM);
386 v = bytestream_get_byte(&s->bytestream);
387 s->color_resolution = ((v & 0x70) >> 4) + 1;
388 s->has_global_palette = (v & 0x80);
389 s->bits_per_pixel = (v & 0x07) + 1;
390 background_color_index = bytestream_get_byte(&s->bytestream);
391 n = bytestream_get_byte(&s->bytestream);
393 s->avctx->sample_aspect_ratio.num = n + 15;
394 s->avctx->sample_aspect_ratio.den = 64;
397 av_dlog(s->avctx, "screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
398 s->screen_width, s->screen_height, s->bits_per_pixel,
399 s->has_global_palette);
401 if (s->has_global_palette) {
402 s->background_color_index = background_color_index;
403 n = 1 << s->bits_per_pixel;
404 if (s->bytestream_end < s->bytestream + n * 3)
405 return AVERROR_INVALIDDATA;
407 gif_read_palette(&s->bytestream, s->global_palette, n);
408 s->bg_color = s->global_palette[s->background_color_index];
410 s->background_color_index = -1;
415 static int gif_parse_next_image(GifState *s, int *got_picture)
418 *got_picture = sizeof(AVPicture);
419 while (s->bytestream < s->bytestream_end) {
420 int code = bytestream_get_byte(&s->bytestream);
422 av_dlog(s->avctx, "code=%02x '%c'\n", code, code);
425 case GIF_IMAGE_SEPARATOR:
426 return gif_read_image(s);
427 case GIF_EXTENSION_INTRODUCER:
428 if ((ret = gif_read_extension(s)) < 0)
436 /* erroneous block label */
437 return AVERROR_INVALIDDATA;
443 static av_cold int gif_decode_init(AVCodecContext *avctx)
445 GifState *s = avctx->priv_data;
449 avctx->pix_fmt = AV_PIX_FMT_RGB32;
450 avcodec_get_frame_defaults(&s->picture);
451 avctx->coded_frame= &s->picture;
452 s->picture.data[0] = NULL;
453 ff_lzw_decode_open(&s->lzw);
457 static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_picture, AVPacket *avpkt)
459 const uint8_t *buf = avpkt->data;
460 int buf_size = avpkt->size;
461 GifState *s = avctx->priv_data;
462 AVFrame *picture = data;
465 s->picture.pts = avpkt->pts;
466 s->picture.pkt_pts = avpkt->pts;
467 s->picture.pkt_dts = avpkt->dts;
468 s->picture.pkt_duration = avpkt->duration;
471 s->bytestream_end = buf + buf_size;
474 s->keyframe = memcmp(s->bytestream, gif87a_sig, 6) == 0 ||
475 memcmp(s->bytestream, gif89a_sig, 6) == 0;
481 if ((ret = gif_read_header1(s)) < 0)
484 if ((ret = av_image_check_size(s->screen_width, s->screen_height, 0, avctx)) < 0)
486 avcodec_set_dimensions(avctx, s->screen_width, s->screen_height);
488 if (s->picture.data[0])
489 avctx->release_buffer(avctx, &s->picture);
491 if ((ret = ff_get_buffer(avctx, &s->picture)) < 0) {
492 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
496 s->picture.pict_type = AV_PICTURE_TYPE_I;
497 s->picture.key_frame = 1;
499 if ((ret = avctx->reget_buffer(avctx, &s->picture)) < 0) {
500 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
504 s->picture.pict_type = AV_PICTURE_TYPE_P;
505 s->picture.key_frame = 0;
508 ret = gif_parse_next_image(s, got_picture);
511 else if (*got_picture)
512 *picture = s->picture;
514 return s->bytestream - buf;
517 static av_cold int gif_decode_close(AVCodecContext *avctx)
519 GifState *s = avctx->priv_data;
521 ff_lzw_decode_close(&s->lzw);
522 if(s->picture.data[0])
523 avctx->release_buffer(avctx, &s->picture);
525 av_freep(&s->idx_line);
526 av_freep(&s->stored_img);
531 static const AVOption options[] = {
532 { "trans_color", "color value (ARGB) that is used instead of transparent color",
533 offsetof(GifState, trans_color), AV_OPT_TYPE_INT,
534 {.i64 = GIF_TRANSPARENT_COLOR}, 0, 0xffffffff,
535 AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM },
539 static const AVClass decoder_class = {
540 .class_name = "gif decoder",
541 .item_name = av_default_item_name,
543 .version = LIBAVUTIL_VERSION_INT,
544 .category = AV_CLASS_CATEGORY_DECODER,
547 AVCodec ff_gif_decoder = {
549 .type = AVMEDIA_TYPE_VIDEO,
550 .id = AV_CODEC_ID_GIF,
551 .priv_data_size = sizeof(GifState),
552 .init = gif_decode_init,
553 .close = gif_decode_close,
554 .decode = gif_decode_frame,
555 .capabilities = CODEC_CAP_DR1,
556 .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
557 .priv_class = &decoder_class,