FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/mss4.c
Date: 2024-02-16 17:37:06
Exec Total Coverage
Lines: 273 302 90.4%
Functions: 13 13 100.0%
Branches: 162 190 85.3%

Line Branch Exec Source
1 /*
2 * Microsoft Screen 4 (aka Microsoft Expression Encoder Screen) decoder
3 * Copyright (c) 2012 Konstantin Shishkov
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * Microsoft Screen 4 (aka Microsoft Titanium Screen 2,
25 * aka Microsoft Expression Encoder Screen) decoder
26 */
27
28 #include "libavutil/thread.h"
29 #include "libavutil/imgutils.h"
30
31 #include "avcodec.h"
32 #include "bytestream.h"
33 #include "codec_internal.h"
34 #include "decode.h"
35 #include "get_bits.h"
36 #include "jpegtables.h"
37 #include "mss34dsp.h"
38 #include "unary.h"
39
40 #define HEADER_SIZE 8
41
42 enum FrameType {
43 INTRA_FRAME = 0,
44 INTER_FRAME,
45 SKIP_FRAME
46 };
47
48 enum BlockType {
49 SKIP_BLOCK = 0,
50 DCT_BLOCK,
51 IMAGE_BLOCK,
52 };
53
54 enum CachePos {
55 LEFT = 0,
56 TOP_LEFT,
57 TOP,
58 };
59
60 static const uint8_t mss4_dc_vlc_lens[2][16] = {
61 { 0, 1, 5, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 },
62 { 0, 3, 1, 1, 1, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0 }
63 };
64
65 static const uint8_t vec_len_syms[2][4] = {
66 { 4, 2, 3, 1 },
67 { 4, 1, 2, 3 }
68 };
69
70 static const uint8_t mss4_vec_entry_vlc_lens[2][16] = {
71 { 0, 2, 2, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
72 { 0, 1, 5, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
73 };
74
75 static const uint8_t mss4_vec_entry_vlc_syms[2][9] = {
76 { 0, 7, 6, 5, 8, 4, 3, 1, 2 },
77 { 0, 2, 3, 4, 5, 6, 7, 1, 8 }
78 };
79
80 #define MAX_ENTRIES 162
81
82 typedef struct MSS4Context {
83 AVFrame *pic;
84
85 int block[64];
86 uint8_t imgbuf[3][16 * 16];
87
88 int quality;
89 uint16_t quant_mat[2][64];
90
91 int *prev_dc[3];
92 ptrdiff_t dc_stride[3];
93 int dc_cache[4][4];
94
95 int prev_vec[3][4];
96 } MSS4Context;
97
98 static VLC dc_vlc[2], ac_vlc[2];
99 static VLC vec_entry_vlc[2];
100
101 12 static av_cold void mss4_init_vlc(VLC *vlc, unsigned *offset,
102 const uint8_t *lens, const uint8_t *syms)
103 {
104 static VLCElem vlc_buf[2146];
105 uint8_t bits[MAX_ENTRIES];
106 int i, j;
107 12 int idx = 0;
108
109
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204 for (i = 0; i < 16; i++) {
110
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924 for (j = 0; j < lens[i]; j++) {
111 732 bits[idx] = i + 1;
112 732 idx++;
113 }
114 }
115
116 12 vlc->table = &vlc_buf[*offset];
117 12 vlc->table_allocated = FF_ARRAY_ELEMS(vlc_buf) - *offset;
118 12 ff_vlc_init_from_lengths(vlc, FFMIN(bits[idx - 1], 9), idx,
119 bits, 1, syms, 1, 1,
120 0, VLC_INIT_STATIC_OVERLONG, NULL);
121 12 *offset += vlc->table_size;
122 12 }
123
124 2 static av_cold void mss4_init_vlcs(void)
125 {
126
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6 for (unsigned i = 0, offset = 0; i < 2; i++) {
127 4 mss4_init_vlc(&dc_vlc[i], &offset, mss4_dc_vlc_lens[i], NULL);
128
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4 mss4_init_vlc(&ac_vlc[i], &offset,
129 i ? ff_mjpeg_bits_ac_chrominance + 1
130 : ff_mjpeg_bits_ac_luminance + 1,
131 i ? ff_mjpeg_val_ac_chrominance
132 : ff_mjpeg_val_ac_luminance);
133 4 mss4_init_vlc(&vec_entry_vlc[i], &offset, mss4_vec_entry_vlc_lens[i],
134 4 mss4_vec_entry_vlc_syms[i]);
135 }
136 2 }
137
138 /* This function returns values in the range
139 * (-range + 1; -range/2] U [range/2; range - 1)
140 * i.e.
141 * nbits = 0 -> 0
142 * nbits = 1 -> -1, 1
143 * nbits = 2 -> -3, -2, 2, 3
144 */
145 315916 static av_always_inline int get_coeff_bits(GetBitContext *gb, int nbits)
146 {
147 int val;
148
149
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315916 if (!nbits)
150 133329 return 0;
151
152 182587 val = get_bits(gb, nbits);
153
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182587 if (val < (1 << (nbits - 1)))
154 98069 val -= (1 << nbits) - 1;
155
156 182587 return val;
157 }
158
159 180586 static inline int get_coeff(GetBitContext *gb, const VLC *vlc,
160 int nb_bits, int max_depth)
161 {
162 180586 int val = get_vlc2(gb, vlc->table, nb_bits, max_depth);
163
164 180586 return get_coeff_bits(gb, val);
165 }
166
167 85284 static int mss4_decode_dct(GetBitContext *gb, VLC *dc_vlc, VLC *ac_vlc,
168 int *block, int *dc_cache,
169 int bx, int by, uint16_t *quant_mat)
170 {
171 85284 int skip, val, pos = 1, zz_pos, dc;
172
173 85284 memset(block, 0, sizeof(*block) * 64);
174
175 85284 dc = get_coeff(gb, dc_vlc, dc_vlc->bits, 2);
176 // DC prediction is the same as in MSS3
177
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85284 if (by) {
178
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84904 if (bx) {
179 int l, tl, t;
180
181 83868 l = dc_cache[LEFT];
182 83868 tl = dc_cache[TOP_LEFT];
183 83868 t = dc_cache[TOP];
184
185
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83868 if (FFABS(t - tl) <= FFABS(l - tl))
186 80876 dc += l;
187 else
188 2992 dc += t;
189 } else {
190 1036 dc += dc_cache[TOP];
191 }
192
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380 } else if (bx) {
193 380 dc += dc_cache[LEFT];
194 }
195 85284 dc_cache[LEFT] = dc;
196 85284 block[0] = dc * quant_mat[0];
197
198
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220682 while (pos < 64) {
199 219785 val = get_vlc2(gb, ac_vlc->table, 9, 2);
200
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219785 if (!val)
201 84387 return 0;
202
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135398 if (val == -1)
203 return -1;
204
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135398 if (val == 0xF0) {
205 68 pos += 16;
206 68 continue;
207 }
208 135330 skip = val >> 4;
209 135330 val = get_coeff_bits(gb, val & 0xF);
210 135330 pos += skip;
211
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135330 if (pos >= 64)
212 return -1;
213
214 135330 zz_pos = ff_zigzag_direct[pos];
215 135330 block[zz_pos] = val * quant_mat[zz_pos];
216 135330 pos++;
217 }
218
219
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897 return pos == 64 ? 0 : -1;
220 }
221
222 14214 static int mss4_decode_dct_block(MSS4Context *c, GetBitContext *gb,
223 uint8_t *dst[3], int mb_x, int mb_y)
224 {
225 int i, j, k, ret;
226 14214 uint8_t *out = dst[0];
227
228
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42642 for (j = 0; j < 2; j++) {
229
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85284 for (i = 0; i < 2; i++) {
230 56856 int xpos = mb_x * 2 + i;
231 56856 c->dc_cache[j][TOP_LEFT] = c->dc_cache[j][TOP];
232 56856 c->dc_cache[j][TOP] = c->prev_dc[0][mb_x * 2 + i];
233 56856 ret = mss4_decode_dct(gb, &dc_vlc[0], &ac_vlc[0], c->block,
234 56856 c->dc_cache[j],
235 56856 xpos, mb_y * 2 + j, c->quant_mat[0]);
236
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56856 if (ret)
237 return ret;
238 56856 c->prev_dc[0][mb_x * 2 + i] = c->dc_cache[j][LEFT];
239
240 56856 ff_mss34_dct_put(out + xpos * 8, c->pic->linesize[0],
241 56856 c->block);
242 }
243 28428 out += 8 * c->pic->linesize[0];
244 }
245
246
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42642 for (i = 1; i < 3; i++) {
247 28428 c->dc_cache[i + 1][TOP_LEFT] = c->dc_cache[i + 1][TOP];
248 28428 c->dc_cache[i + 1][TOP] = c->prev_dc[i][mb_x];
249 28428 ret = mss4_decode_dct(gb, &dc_vlc[1], &ac_vlc[1],
250 28428 c->block, c->dc_cache[i + 1], mb_x, mb_y,
251 28428 c->quant_mat[1]);
252
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28428 if (ret)
253 return ret;
254 28428 c->prev_dc[i][mb_x] = c->dc_cache[i + 1][LEFT];
255
256 28428 ff_mss34_dct_put(c->imgbuf[i], 8, c->block);
257 28428 out = dst[i] + mb_x * 16;
258 // Since the DCT block is coded as YUV420 and the whole frame as YUV444,
259 // we need to scale chroma.
260
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483276 for (j = 0; j < 16; j++) {
261
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4093632 for (k = 0; k < 8; k++)
262 3638784 AV_WN16A(out + k * 2, c->imgbuf[i][k + (j & ~1) * 4] * 0x101);
263 454848 out += c->pic->linesize[i];
264 }
265 }
266
267 14214 return 0;
268 }
269
270 281245 static void read_vec_pos(GetBitContext *gb, int *vec_pos, int *sel_flag,
271 int *sel_len, int *prev)
272 {
273 281245 int i, y_flag = 0;
274
275
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1124980 for (i = 2; i >= 0; i--) {
276
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843735 if (!sel_flag[i]) {
277 192630 vec_pos[i] = 0;
278 192630 continue;
279 }
280
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651105 if ((!i && !y_flag) || get_bits1(gb)) {
281
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554066 if (sel_len[i] > 0) {
282 549560 int pval = prev[i];
283 549560 vec_pos[i] = get_bits(gb, sel_len[i]);
284
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549560 if (vec_pos[i] >= pval)
285 297455 vec_pos[i]++;
286 } else {
287 4506 vec_pos[i] = !prev[i];
288 }
289 554066 y_flag = 1;
290 } else {
291 97039 vec_pos[i] = prev[i];
292 }
293 }
294 281245 }
295
296 8739072 static int get_value_cached(GetBitContext *gb, int vec_pos, uint8_t *vec,
297 int vec_size, int component, int shift, int *prev)
298 {
299
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8739072 if (vec_pos < vec_size)
300 8442194 return vec[vec_pos];
301
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296878 if (!get_bits1(gb))
302 46525 return prev[component];
303 250353 prev[component] = get_bits(gb, 8 - shift) << shift;
304 250353 return prev[component];
305 }
306
307 #define MKVAL(vals) ((vals)[0] | ((vals)[1] << 3) | ((vals)[2] << 6))
308
309 /* Image mode - the hardest to comprehend MSS4 coding mode.
310 *
311 * In this mode all three 16x16 blocks are coded together with a method
312 * remotely similar to the methods employed in MSS1-MSS3.
313 * The idea is that every component has a vector of 1-4 most common symbols
314 * and an escape mode for reading new value from the bitstream. Decoding
315 * consists of retrieving pixel values from the vector or reading new ones
316 * from the bitstream; depending on flags read from the bitstream, these vector
317 * positions can be updated or reused from the state of the previous line
318 * or previous pixel.
319 */
320 11379 static int mss4_decode_image_block(MSS4Context *ctx, GetBitContext *gb,
321 uint8_t *picdst[3], int mb_x, int mb_y)
322 {
323 uint8_t vec[3][4];
324 int vec_len[3];
325 int sel_len[3], sel_flag[3];
326 int i, j, k, mode, split;
327 11379 int prev_vec1 = 0, prev_split = 0;
328 11379 int vals[3] = { 0 };
329 11379 int prev_pix[3] = { 0 };
330 11379 int prev_mode[16] = { 0 };
331 uint8_t *dst[3];
332
333
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11379 const int val_shift = ctx->quality == 100 ? 0 : 2;
334
335
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45516 for (i = 0; i < 3; i++)
336 34137 dst[i] = ctx->imgbuf[i];
337
338
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45516 for (i = 0; i < 3; i++) {
339 34137 vec_len[i] = vec_len_syms[!!i][get_unary(gb, 0, 3)];
340
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129439 for (j = 0; j < vec_len[i]; j++) {
341 95302 vec[i][j] = get_coeff(gb, &vec_entry_vlc[!!i], 5, 1);
342 95302 vec[i][j] += ctx->prev_vec[i][j];
343 95302 ctx->prev_vec[i][j] = vec[i][j];
344 }
345 34137 sel_flag[i] = vec_len[i] > 1;
346 34137 sel_len[i] = vec_len[i] > 2 ? vec_len[i] - 2 : 0;
347 }
348
349
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193443 for (j = 0; j < 16; j++) {
350
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182064 if (get_bits1(gb)) {
351 56004 split = 0;
352
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56004 if (get_bits1(gb)) {
353 35860 prev_mode[0] = 0;
354 35860 vals[0] = vals[1] = vals[2] = 0;
355 35860 mode = 2;
356 } else {
357 20144 mode = get_bits1(gb);
358
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20144 if (mode)
359 3817 split = get_bits(gb, 4);
360 }
361
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952068 for (i = 0; i < 16; i++) {
362
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896064 if (mode <= 1) {
363 322304 vals[0] = prev_mode[i] & 7;
364 322304 vals[1] = (prev_mode[i] >> 3) & 7;
365 322304 vals[2] = prev_mode[i] >> 6;
366
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322304 if (mode == 1 && i == split) {
367 3817 read_vec_pos(gb, vals, sel_flag, sel_len, vals);
368 }
369
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573760 } else if (mode == 2) {
370
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573760 if (get_bits1(gb))
371 261389 read_vec_pos(gb, vals, sel_flag, sel_len, vals);
372 }
373
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3584256 for (k = 0; k < 3; k++)
374 2688192 *dst[k]++ = get_value_cached(gb, vals[k], vec[k],
375 vec_len[k], k,
376 val_shift, prev_pix);
377 896064 prev_mode[i] = MKVAL(vals);
378 }
379 } else {
380
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126060 if (get_bits1(gb)) {
381 21425 split = get_bits(gb, 4);
382
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21425 if (split >= prev_split)
383 15525 split++;
384 21425 prev_split = split;
385 } else {
386 104635 split = prev_split;
387 }
388
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126060 if (split) {
389 109261 vals[0] = prev_mode[0] & 7;
390 109261 vals[1] = (prev_mode[0] >> 3) & 7;
391 109261 vals[2] = prev_mode[0] >> 6;
392
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437044 for (i = 0; i < 3; i++) {
393
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5442705 for (k = 0; k < split; k++) {
394 5114922 *dst[i]++ = get_value_cached(gb, vals[i], vec[i],
395 vec_len[i], i, val_shift,
396 prev_pix);
397 5114922 prev_mode[k] = MKVAL(vals);
398 }
399 }
400 }
401
402
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126060 if (split != 16) {
403 22314 vals[0] = prev_vec1 & 7;
404 22314 vals[1] = (prev_vec1 >> 3) & 7;
405 22314 vals[2] = prev_vec1 >> 6;
406
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22314 if (get_bits1(gb)) {
407 16039 read_vec_pos(gb, vals, sel_flag, sel_len, vals);
408 16039 prev_vec1 = MKVAL(vals);
409 }
410
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89256 for (i = 0; i < 3; i++) {
411
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1002900 for (k = 0; k < 16 - split; k++) {
412 935958 *dst[i]++ = get_value_cached(gb, vals[i], vec[i],
413 vec_len[i], i, val_shift,
414 prev_pix);
415 935958 prev_mode[split + k] = MKVAL(vals);
416 }
417 }
418 }
419 }
420 }
421
422
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45516 for (i = 0; i < 3; i++)
423
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580329 for (j = 0; j < 16; j++)
424 546192 memcpy(picdst[i] + mb_x * 16 + j * ctx->pic->linesize[i],
425 546192 ctx->imgbuf[i] + j * 16, 16);
426
427 11379 return 0;
428 }
429
430 175050 static inline void mss4_update_dc_cache(MSS4Context *c, int mb_x)
431 {
432 int i;
433
434 175050 c->dc_cache[0][TOP] = c->prev_dc[0][mb_x * 2 + 1];
435 175050 c->dc_cache[0][LEFT] = 0;
436 175050 c->dc_cache[1][TOP] = 0;
437 175050 c->dc_cache[1][LEFT] = 0;
438
439
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525150 for (i = 0; i < 2; i++)
440 350100 c->prev_dc[0][mb_x * 2 + i] = 0;
441
442
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525150 for (i = 1; i < 3; i++) {
443 350100 c->dc_cache[i + 1][TOP] = c->prev_dc[i][mb_x];
444 350100 c->dc_cache[i + 1][LEFT] = 0;
445 350100 c->prev_dc[i][mb_x] = 0;
446 }
447 175050 }
448
449 145 static int mss4_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
450 int *got_frame, AVPacket *avpkt)
451 {
452 145 const uint8_t *buf = avpkt->data;
453 145 int buf_size = avpkt->size;
454 145 MSS4Context *c = avctx->priv_data;
455 GetBitContext gb;
456 GetByteContext bc;
457 uint8_t *dst[3];
458 int width, height, quality, frame_type;
459 int x, y, i, mb_width, mb_height, blk_type;
460 int ret;
461
462
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145 if (buf_size < HEADER_SIZE) {
463 av_log(avctx, AV_LOG_ERROR,
464 "Frame should have at least %d bytes, got %d instead\n",
465 HEADER_SIZE, buf_size);
466 return AVERROR_INVALIDDATA;
467 }
468
469 145 bytestream2_init(&bc, buf, buf_size);
470 145 width = bytestream2_get_be16(&bc);
471 145 height = bytestream2_get_be16(&bc);
472 145 bytestream2_skip(&bc, 2);
473 145 quality = bytestream2_get_byte(&bc);
474 145 frame_type = bytestream2_get_byte(&bc);
475
476
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145 if (width > avctx->width ||
477
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145 height != avctx->height) {
478 av_log(avctx, AV_LOG_ERROR, "Invalid frame dimensions %dx%d\n",
479 width, height);
480 return AVERROR_INVALIDDATA;
481 }
482
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145 if (av_image_check_size2(width, height, avctx->max_pixels, AV_PIX_FMT_NONE, 0, avctx) < 0)
483 return AVERROR_INVALIDDATA;
484
485
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145 if (quality < 1 || quality > 100) {
486 av_log(avctx, AV_LOG_ERROR, "Invalid quality setting %d\n", quality);
487 return AVERROR_INVALIDDATA;
488 }
489
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145 if ((frame_type & ~3) || frame_type == 3) {
490 av_log(avctx, AV_LOG_ERROR, "Invalid frame type %d\n", frame_type);
491 return AVERROR_INVALIDDATA;
492 }
493
494
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145 if (frame_type != SKIP_FRAME && !bytestream2_get_bytes_left(&bc)) {
495 av_log(avctx, AV_LOG_ERROR,
496 "Empty frame found but it is not a skip frame.\n");
497 return AVERROR_INVALIDDATA;
498 }
499 145 mb_width = FFALIGN(width, 16) >> 4;
500 145 mb_height = FFALIGN(height, 16) >> 4;
501
502
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145 if (frame_type != SKIP_FRAME && 8*buf_size < 8*HEADER_SIZE + mb_width*mb_height)
503 return AVERROR_INVALIDDATA;
504
505
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145 if ((ret = ff_reget_buffer(avctx, c->pic, 0)) < 0)
506 return ret;
507
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145 if (frame_type == INTRA_FRAME)
508 3 c->pic->flags |= AV_FRAME_FLAG_KEY;
509 else
510 142 c->pic->flags &= ~AV_FRAME_FLAG_KEY;
511 145 c->pic->pict_type = (frame_type == INTRA_FRAME) ? AV_PICTURE_TYPE_I
512
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145 : AV_PICTURE_TYPE_P;
513
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145 if (frame_type == SKIP_FRAME) {
514 98 *got_frame = 1;
515
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98 if ((ret = av_frame_ref(rframe, c->pic)) < 0)
516 return ret;
517
518 98 return buf_size;
519 }
520
521
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47 if (c->quality != quality) {
522 2 c->quality = quality;
523
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6 for (i = 0; i < 2; i++)
524 4 ff_mss34_gen_quant_mat(c->quant_mat[i], quality, !i);
525 }
526
527
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47 if ((ret = init_get_bits8(&gb, buf + HEADER_SIZE, buf_size - HEADER_SIZE)) < 0)
528 return ret;
529 47 dst[0] = c->pic->data[0];
530 47 dst[1] = c->pic->data[1];
531 47 dst[2] = c->pic->data[2];
532
533 47 memset(c->prev_vec, 0, sizeof(c->prev_vec));
534
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2519 for (y = 0; y < mb_height; y++) {
535 2472 memset(c->dc_cache, 0, sizeof(c->dc_cache));
536
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191736 for (x = 0; x < mb_width; x++) {
537 189264 blk_type = decode012(&gb);
538
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189264 switch (blk_type) {
539 14214 case DCT_BLOCK:
540
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14214 if (mss4_decode_dct_block(c, &gb, dst, x, y) < 0) {
541 av_log(avctx, AV_LOG_ERROR,
542 "Error decoding DCT block %d,%d\n",
543 x, y);
544 return AVERROR_INVALIDDATA;
545 }
546 14214 break;
547 11379 case IMAGE_BLOCK:
548
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11379 if (mss4_decode_image_block(c, &gb, dst, x, y) < 0) {
549 av_log(avctx, AV_LOG_ERROR,
550 "Error decoding VQ block %d,%d\n",
551 x, y);
552 return AVERROR_INVALIDDATA;
553 }
554 11379 break;
555 163671 case SKIP_BLOCK:
556
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163671 if (frame_type == INTRA_FRAME) {
557 av_log(avctx, AV_LOG_ERROR, "Skip block in intra frame\n");
558 return AVERROR_INVALIDDATA;
559 }
560 163671 break;
561 }
562
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189264 if (blk_type != DCT_BLOCK)
563 175050 mss4_update_dc_cache(c, x);
564 }
565 2472 dst[0] += c->pic->linesize[0] * 16;
566 2472 dst[1] += c->pic->linesize[1] * 16;
567 2472 dst[2] += c->pic->linesize[2] * 16;
568 }
569
570
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47 if ((ret = av_frame_ref(rframe, c->pic)) < 0)
571 return ret;
572
573 47 *got_frame = 1;
574
575 47 return buf_size;
576 }
577
578 4 static av_cold int mss4_decode_end(AVCodecContext *avctx)
579 {
580 4 MSS4Context * const c = avctx->priv_data;
581 int i;
582
583 4 av_frame_free(&c->pic);
584
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16 for (i = 0; i < 3; i++)
585 12 av_freep(&c->prev_dc[i]);
586
587 4 return 0;
588 }
589
590 4 static av_cold int mss4_decode_init(AVCodecContext *avctx)
591 {
592 static AVOnce init_static_once = AV_ONCE_INIT;
593 4 MSS4Context * const c = avctx->priv_data;
594 int i;
595
596
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16 for (i = 0; i < 3; i++) {
597
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12 c->dc_stride[i] = FFALIGN(avctx->width, 16) >> (2 + !!i);
598 12 c->prev_dc[i] = av_malloc_array(c->dc_stride[i], sizeof(**c->prev_dc));
599
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12 if (!c->prev_dc[i]) {
600 av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");
601 return AVERROR(ENOMEM);
602 }
603 }
604
605 4 c->pic = av_frame_alloc();
606
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4 if (!c->pic)
607 return AVERROR(ENOMEM);
608
609 4 avctx->pix_fmt = AV_PIX_FMT_YUV444P;
610
611 4 ff_thread_once(&init_static_once, mss4_init_vlcs);
612
613 4 return 0;
614 }
615
616 const FFCodec ff_mts2_decoder = {
617 .p.name = "mts2",
618 CODEC_LONG_NAME("MS Expression Encoder Screen"),
619 .p.type = AVMEDIA_TYPE_VIDEO,
620 .p.id = AV_CODEC_ID_MTS2,
621 .priv_data_size = sizeof(MSS4Context),
622 .init = mss4_decode_init,
623 .close = mss4_decode_end,
624 FF_CODEC_DECODE_CB(mss4_decode_frame),
625 .p.capabilities = AV_CODEC_CAP_DR1,
626 .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
627 };
628