FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/mss4.c
Date: 2021-09-26 18:22:30
Exec Total Coverage
Lines: 270 298 90.6%
Branches: 159 186 85.5%

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