lavc: add a wrapper for AVCodecContext.get_buffer().
[libav.git] / libavcodec / gifdec.c
1 /*
2 * GIF decoder
3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2006 Baptiste Coudurier
5 *
6 * This file is part of Libav.
7 *
8 * Libav is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * Libav is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with Libav; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 //#define DEBUG
24
25 #include "libavutil/imgutils.h"
26 #include "avcodec.h"
27 #include "bytestream.h"
28 #include "internal.h"
29 #include "lzw.h"
30
31 #define GCE_DISPOSAL_NONE 0
32 #define GCE_DISPOSAL_INPLACE 1
33 #define GCE_DISPOSAL_BACKGROUND 2
34 #define GCE_DISPOSAL_RESTORE 3
35
36 typedef struct GifState {
37 AVFrame picture;
38 int screen_width;
39 int screen_height;
40 int bits_per_pixel;
41 int background_color_index;
42 int transparent_color_index;
43 int color_resolution;
44 uint32_t *image_palette;
45
46 /* after the frame is displayed, the disposal method is used */
47 int gce_disposal;
48 /* delay during which the frame is shown */
49 int gce_delay;
50
51 /* LZW compatible decoder */
52 const uint8_t *bytestream;
53 const uint8_t *bytestream_end;
54 LZWState *lzw;
55
56 /* aux buffers */
57 uint8_t global_palette[256 * 3];
58 uint8_t local_palette[256 * 3];
59
60 AVCodecContext* avctx;
61 } GifState;
62
63 static const uint8_t gif87a_sig[6] = "GIF87a";
64 static const uint8_t gif89a_sig[6] = "GIF89a";
65
66 static int gif_read_image(GifState *s)
67 {
68 int left, top, width, height, bits_per_pixel, code_size, flags;
69 int is_interleaved, has_local_palette, y, pass, y1, linesize, n, i;
70 uint8_t *ptr, *spal, *palette, *ptr1;
71
72 left = bytestream_get_le16(&s->bytestream);
73 top = bytestream_get_le16(&s->bytestream);
74 width = bytestream_get_le16(&s->bytestream);
75 height = bytestream_get_le16(&s->bytestream);
76 flags = bytestream_get_byte(&s->bytestream);
77 is_interleaved = flags & 0x40;
78 has_local_palette = flags & 0x80;
79 bits_per_pixel = (flags & 0x07) + 1;
80
81 av_dlog(s->avctx, "gif: image x=%d y=%d w=%d h=%d\n", left, top, width, height);
82
83 if (has_local_palette) {
84 bytestream_get_buffer(&s->bytestream, s->local_palette, 3 * (1 << bits_per_pixel));
85 palette = s->local_palette;
86 } else {
87 palette = s->global_palette;
88 bits_per_pixel = s->bits_per_pixel;
89 }
90
91 /* verify that all the image is inside the screen dimensions */
92 if (left + width > s->screen_width ||
93 top + height > s->screen_height)
94 return AVERROR(EINVAL);
95
96 /* build the palette */
97 n = (1 << bits_per_pixel);
98 spal = palette;
99 for(i = 0; i < n; i++) {
100 s->image_palette[i] = (0xffu << 24) | AV_RB24(spal);
101 spal += 3;
102 }
103 for(; i < 256; i++)
104 s->image_palette[i] = (0xffu << 24);
105 /* handle transparency */
106 if (s->transparent_color_index >= 0)
107 s->image_palette[s->transparent_color_index] = 0;
108
109 /* now get the image data */
110 code_size = bytestream_get_byte(&s->bytestream);
111 ff_lzw_decode_init(s->lzw, code_size, s->bytestream,
112 s->bytestream_end - s->bytestream, FF_LZW_GIF);
113
114 /* read all the image */
115 linesize = s->picture.linesize[0];
116 ptr1 = s->picture.data[0] + top * linesize + left;
117 ptr = ptr1;
118 pass = 0;
119 y1 = 0;
120 for (y = 0; y < height; y++) {
121 ff_lzw_decode(s->lzw, ptr, width);
122 if (is_interleaved) {
123 switch(pass) {
124 default:
125 case 0:
126 case 1:
127 y1 += 8;
128 ptr += linesize * 8;
129 if (y1 >= height) {
130 y1 = pass ? 2 : 4;
131 ptr = ptr1 + linesize * y1;
132 pass++;
133 }
134 break;
135 case 2:
136 y1 += 4;
137 ptr += linesize * 4;
138 if (y1 >= height) {
139 y1 = 1;
140 ptr = ptr1 + linesize;
141 pass++;
142 }
143 break;
144 case 3:
145 y1 += 2;
146 ptr += linesize * 2;
147 break;
148 }
149 } else {
150 ptr += linesize;
151 }
152 }
153 /* read the garbage data until end marker is found */
154 ff_lzw_decode_tail(s->lzw);
155 s->bytestream = ff_lzw_cur_ptr(s->lzw);
156 return 0;
157 }
158
159 static int gif_read_extension(GifState *s)
160 {
161 int ext_code, ext_len, i, gce_flags, gce_transparent_index;
162
163 /* extension */
164 ext_code = bytestream_get_byte(&s->bytestream);
165 ext_len = bytestream_get_byte(&s->bytestream);
166
167 av_dlog(s->avctx, "gif: ext_code=0x%x len=%d\n", ext_code, ext_len);
168
169 switch(ext_code) {
170 case 0xf9:
171 if (ext_len != 4)
172 goto discard_ext;
173 s->transparent_color_index = -1;
174 gce_flags = bytestream_get_byte(&s->bytestream);
175 s->gce_delay = bytestream_get_le16(&s->bytestream);
176 gce_transparent_index = bytestream_get_byte(&s->bytestream);
177 if (gce_flags & 0x01)
178 s->transparent_color_index = gce_transparent_index;
179 else
180 s->transparent_color_index = -1;
181 s->gce_disposal = (gce_flags >> 2) & 0x7;
182
183 av_dlog(s->avctx, "gif: gce_flags=%x delay=%d tcolor=%d disposal=%d\n",
184 gce_flags, s->gce_delay,
185 s->transparent_color_index, s->gce_disposal);
186
187 ext_len = bytestream_get_byte(&s->bytestream);
188 break;
189 }
190
191 /* NOTE: many extension blocks can come after */
192 discard_ext:
193 while (ext_len != 0) {
194 for (i = 0; i < ext_len; i++)
195 bytestream_get_byte(&s->bytestream);
196 ext_len = bytestream_get_byte(&s->bytestream);
197
198 av_dlog(s->avctx, "gif: ext_len1=%d\n", ext_len);
199 }
200 return 0;
201 }
202
203 static int gif_read_header1(GifState *s)
204 {
205 uint8_t sig[6];
206 int v, n;
207 int has_global_palette;
208
209 if (s->bytestream_end < s->bytestream + 13)
210 return -1;
211
212 /* read gif signature */
213 bytestream_get_buffer(&s->bytestream, sig, 6);
214 if (memcmp(sig, gif87a_sig, 6) != 0 &&
215 memcmp(sig, gif89a_sig, 6) != 0)
216 return -1;
217
218 /* read screen header */
219 s->transparent_color_index = -1;
220 s->screen_width = bytestream_get_le16(&s->bytestream);
221 s->screen_height = bytestream_get_le16(&s->bytestream);
222 if( (unsigned)s->screen_width > 32767
223 || (unsigned)s->screen_height > 32767){
224 av_log(NULL, AV_LOG_ERROR, "picture size too large\n");
225 return -1;
226 }
227
228 v = bytestream_get_byte(&s->bytestream);
229 s->color_resolution = ((v & 0x70) >> 4) + 1;
230 has_global_palette = (v & 0x80);
231 s->bits_per_pixel = (v & 0x07) + 1;
232 s->background_color_index = bytestream_get_byte(&s->bytestream);
233 bytestream_get_byte(&s->bytestream); /* ignored */
234
235 av_dlog(s->avctx, "gif: screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
236 s->screen_width, s->screen_height, s->bits_per_pixel,
237 has_global_palette);
238
239 if (has_global_palette) {
240 n = 1 << s->bits_per_pixel;
241 if (s->bytestream_end < s->bytestream + n * 3)
242 return -1;
243 bytestream_get_buffer(&s->bytestream, s->global_palette, n * 3);
244 }
245 return 0;
246 }
247
248 static int gif_parse_next_image(GifState *s)
249 {
250 while (s->bytestream < s->bytestream_end) {
251 int code = bytestream_get_byte(&s->bytestream);
252
253 av_dlog(s->avctx, "gif: code=%02x '%c'\n", code, code);
254
255 switch (code) {
256 case ',':
257 return gif_read_image(s);
258 case '!':
259 if (gif_read_extension(s) < 0)
260 return -1;
261 break;
262 case ';':
263 /* end of image */
264 default:
265 /* error or erroneous EOF */
266 return -1;
267 }
268 }
269 return -1;
270 }
271
272 static av_cold int gif_decode_init(AVCodecContext *avctx)
273 {
274 GifState *s = avctx->priv_data;
275
276 s->avctx = avctx;
277
278 avcodec_get_frame_defaults(&s->picture);
279 avctx->coded_frame= &s->picture;
280 s->picture.data[0] = NULL;
281 ff_lzw_decode_open(&s->lzw);
282 return 0;
283 }
284
285 static int gif_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
286 {
287 const uint8_t *buf = avpkt->data;
288 int buf_size = avpkt->size;
289 GifState *s = avctx->priv_data;
290 AVFrame *picture = data;
291 int ret;
292
293 s->bytestream = buf;
294 s->bytestream_end = buf + buf_size;
295 if (gif_read_header1(s) < 0)
296 return -1;
297
298 avctx->pix_fmt = AV_PIX_FMT_PAL8;
299 if (av_image_check_size(s->screen_width, s->screen_height, 0, avctx))
300 return -1;
301 avcodec_set_dimensions(avctx, s->screen_width, s->screen_height);
302
303 if (s->picture.data[0])
304 avctx->release_buffer(avctx, &s->picture);
305 if (ff_get_buffer(avctx, &s->picture) < 0) {
306 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
307 return -1;
308 }
309 s->image_palette = (uint32_t *)s->picture.data[1];
310 ret = gif_parse_next_image(s);
311 if (ret < 0)
312 return ret;
313
314 *picture = s->picture;
315 *data_size = sizeof(AVPicture);
316 return s->bytestream - buf;
317 }
318
319 static av_cold int gif_decode_close(AVCodecContext *avctx)
320 {
321 GifState *s = avctx->priv_data;
322
323 ff_lzw_decode_close(&s->lzw);
324 if(s->picture.data[0])
325 avctx->release_buffer(avctx, &s->picture);
326 return 0;
327 }
328
329 AVCodec ff_gif_decoder = {
330 .name = "gif",
331 .type = AVMEDIA_TYPE_VIDEO,
332 .id = AV_CODEC_ID_GIF,
333 .priv_data_size = sizeof(GifState),
334 .init = gif_decode_init,
335 .close = gif_decode_close,
336 .decode = gif_decode_frame,
337 .capabilities = CODEC_CAP_DR1,
338 .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
339 };