1 | // Copyright 2011 Google Inc. All Rights Reserved. |
2 | // |
3 | // Use of this source code is governed by a BSD-style license |
4 | // that can be found in the COPYING file in the root of the source |
5 | // tree. An additional intellectual property rights grant can be found |
6 | // in the file PATENTS. All contributing project authors may |
7 | // be found in the AUTHORS file in the root of the source tree. |
8 | // ----------------------------------------------------------------------------- |
9 | // |
10 | // Quantization |
11 | // |
12 | // Author: Skal (pascal.massimino@gmail.com) |
13 | |
14 | #include <assert.h> |
15 | #include <math.h> |
16 | #include <stdlib.h> // for abs() |
17 | |
18 | #include "src/dsp/quant.h" |
19 | #include "src/enc/vp8i_enc.h" |
20 | #include "src/enc/cost_enc.h" |
21 | |
22 | #define DO_TRELLIS_I4 1 |
23 | #define DO_TRELLIS_I16 1 // not a huge gain, but ok at low bitrate. |
24 | #define DO_TRELLIS_UV 0 // disable trellis for UV. Risky. Not worth. |
25 | #define USE_TDISTO 1 |
26 | |
27 | #define MID_ALPHA 64 // neutral value for susceptibility |
28 | #define MIN_ALPHA 30 // lowest usable value for susceptibility |
29 | #define MAX_ALPHA 100 // higher meaningful value for susceptibility |
30 | |
31 | #define SNS_TO_DQ 0.9 // Scaling constant between the sns value and the QP |
32 | // power-law modulation. Must be strictly less than 1. |
33 | |
34 | // number of non-zero coeffs below which we consider the block very flat |
35 | // (and apply a penalty to complex predictions) |
36 | #define FLATNESS_LIMIT_I16 0 // I16 mode (special case) |
37 | #define FLATNESS_LIMIT_I4 3 // I4 mode |
38 | #define FLATNESS_LIMIT_UV 2 // UV mode |
39 | #define FLATNESS_PENALTY 140 // roughly ~1bit per block |
40 | |
41 | #define MULT_8B(a, b) (((a) * (b) + 128) >> 8) |
42 | |
43 | #define RD_DISTO_MULT 256 // distortion multiplier (equivalent of lambda) |
44 | |
45 | // #define DEBUG_BLOCK |
46 | |
47 | //------------------------------------------------------------------------------ |
48 | |
49 | #if defined(DEBUG_BLOCK) |
50 | |
51 | #include <stdio.h> |
52 | #include <stdlib.h> |
53 | |
54 | static void PrintBlockInfo(const VP8EncIterator* const it, |
55 | const VP8ModeScore* const rd) { |
56 | int i, j; |
57 | const int is_i16 = (it->mb_->type_ == 1); |
58 | const uint8_t* const y_in = it->yuv_in_ + Y_OFF_ENC; |
59 | const uint8_t* const y_out = it->yuv_out_ + Y_OFF_ENC; |
60 | const uint8_t* const uv_in = it->yuv_in_ + U_OFF_ENC; |
61 | const uint8_t* const uv_out = it->yuv_out_ + U_OFF_ENC; |
62 | printf("SOURCE / OUTPUT / ABS DELTA\n" ); |
63 | for (j = 0; j < 16; ++j) { |
64 | for (i = 0; i < 16; ++i) printf("%3d " , y_in[i + j * BPS]); |
65 | printf(" " ); |
66 | for (i = 0; i < 16; ++i) printf("%3d " , y_out[i + j * BPS]); |
67 | printf(" " ); |
68 | for (i = 0; i < 16; ++i) { |
69 | printf("%1d " , abs(y_in[i + j * BPS] - y_out[i + j * BPS])); |
70 | } |
71 | printf("\n" ); |
72 | } |
73 | printf("\n" ); // newline before the U/V block |
74 | for (j = 0; j < 8; ++j) { |
75 | for (i = 0; i < 8; ++i) printf("%3d " , uv_in[i + j * BPS]); |
76 | printf(" " ); |
77 | for (i = 8; i < 16; ++i) printf("%3d " , uv_in[i + j * BPS]); |
78 | printf(" " ); |
79 | for (i = 0; i < 8; ++i) printf("%3d " , uv_out[i + j * BPS]); |
80 | printf(" " ); |
81 | for (i = 8; i < 16; ++i) printf("%3d " , uv_out[i + j * BPS]); |
82 | printf(" " ); |
83 | for (i = 0; i < 8; ++i) { |
84 | printf("%1d " , abs(uv_out[i + j * BPS] - uv_in[i + j * BPS])); |
85 | } |
86 | printf(" " ); |
87 | for (i = 8; i < 16; ++i) { |
88 | printf("%1d " , abs(uv_out[i + j * BPS] - uv_in[i + j * BPS])); |
89 | } |
90 | printf("\n" ); |
91 | } |
92 | printf("\nD:%d SD:%d R:%d H:%d nz:0x%x score:%d\n" , |
93 | (int)rd->D, (int)rd->SD, (int)rd->R, (int)rd->H, (int)rd->nz, |
94 | (int)rd->score); |
95 | if (is_i16) { |
96 | printf("Mode: %d\n" , rd->mode_i16); |
97 | printf("y_dc_levels:" ); |
98 | for (i = 0; i < 16; ++i) printf("%3d " , rd->y_dc_levels[i]); |
99 | printf("\n" ); |
100 | } else { |
101 | printf("Modes[16]: " ); |
102 | for (i = 0; i < 16; ++i) printf("%d " , rd->modes_i4[i]); |
103 | printf("\n" ); |
104 | } |
105 | printf("y_ac_levels:\n" ); |
106 | for (j = 0; j < 16; ++j) { |
107 | for (i = is_i16 ? 1 : 0; i < 16; ++i) { |
108 | printf("%4d " , rd->y_ac_levels[j][i]); |
109 | } |
110 | printf("\n" ); |
111 | } |
112 | printf("\n" ); |
113 | printf("uv_levels (mode=%d):\n" , rd->mode_uv); |
114 | for (j = 0; j < 8; ++j) { |
115 | for (i = 0; i < 16; ++i) { |
116 | printf("%4d " , rd->uv_levels[j][i]); |
117 | } |
118 | printf("\n" ); |
119 | } |
120 | } |
121 | |
122 | #endif // DEBUG_BLOCK |
123 | |
124 | //------------------------------------------------------------------------------ |
125 | |
126 | static WEBP_INLINE int clip(int v, int m, int M) { |
127 | return v < m ? m : v > M ? M : v; |
128 | } |
129 | |
130 | static const uint8_t kZigzag[16] = { |
131 | 0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15 |
132 | }; |
133 | |
134 | static const uint8_t kDcTable[128] = { |
135 | 4, 5, 6, 7, 8, 9, 10, 10, |
136 | 11, 12, 13, 14, 15, 16, 17, 17, |
137 | 18, 19, 20, 20, 21, 21, 22, 22, |
138 | 23, 23, 24, 25, 25, 26, 27, 28, |
139 | 29, 30, 31, 32, 33, 34, 35, 36, |
140 | 37, 37, 38, 39, 40, 41, 42, 43, |
141 | 44, 45, 46, 46, 47, 48, 49, 50, |
142 | 51, 52, 53, 54, 55, 56, 57, 58, |
143 | 59, 60, 61, 62, 63, 64, 65, 66, |
144 | 67, 68, 69, 70, 71, 72, 73, 74, |
145 | 75, 76, 76, 77, 78, 79, 80, 81, |
146 | 82, 83, 84, 85, 86, 87, 88, 89, |
147 | 91, 93, 95, 96, 98, 100, 101, 102, |
148 | 104, 106, 108, 110, 112, 114, 116, 118, |
149 | 122, 124, 126, 128, 130, 132, 134, 136, |
150 | 138, 140, 143, 145, 148, 151, 154, 157 |
151 | }; |
152 | |
153 | static const uint16_t kAcTable[128] = { |
154 | 4, 5, 6, 7, 8, 9, 10, 11, |
155 | 12, 13, 14, 15, 16, 17, 18, 19, |
156 | 20, 21, 22, 23, 24, 25, 26, 27, |
157 | 28, 29, 30, 31, 32, 33, 34, 35, |
158 | 36, 37, 38, 39, 40, 41, 42, 43, |
159 | 44, 45, 46, 47, 48, 49, 50, 51, |
160 | 52, 53, 54, 55, 56, 57, 58, 60, |
161 | 62, 64, 66, 68, 70, 72, 74, 76, |
162 | 78, 80, 82, 84, 86, 88, 90, 92, |
163 | 94, 96, 98, 100, 102, 104, 106, 108, |
164 | 110, 112, 114, 116, 119, 122, 125, 128, |
165 | 131, 134, 137, 140, 143, 146, 149, 152, |
166 | 155, 158, 161, 164, 167, 170, 173, 177, |
167 | 181, 185, 189, 193, 197, 201, 205, 209, |
168 | 213, 217, 221, 225, 229, 234, 239, 245, |
169 | 249, 254, 259, 264, 269, 274, 279, 284 |
170 | }; |
171 | |
172 | static const uint16_t kAcTable2[128] = { |
173 | 8, 8, 9, 10, 12, 13, 15, 17, |
174 | 18, 20, 21, 23, 24, 26, 27, 29, |
175 | 31, 32, 34, 35, 37, 38, 40, 41, |
176 | 43, 44, 46, 48, 49, 51, 52, 54, |
177 | 55, 57, 58, 60, 62, 63, 65, 66, |
178 | 68, 69, 71, 72, 74, 75, 77, 79, |
179 | 80, 82, 83, 85, 86, 88, 89, 93, |
180 | 96, 99, 102, 105, 108, 111, 114, 117, |
181 | 120, 124, 127, 130, 133, 136, 139, 142, |
182 | 145, 148, 151, 155, 158, 161, 164, 167, |
183 | 170, 173, 176, 179, 184, 189, 193, 198, |
184 | 203, 207, 212, 217, 221, 226, 230, 235, |
185 | 240, 244, 249, 254, 258, 263, 268, 274, |
186 | 280, 286, 292, 299, 305, 311, 317, 323, |
187 | 330, 336, 342, 348, 354, 362, 370, 379, |
188 | 385, 393, 401, 409, 416, 424, 432, 440 |
189 | }; |
190 | |
191 | static const uint8_t kBiasMatrices[3][2] = { // [luma-ac,luma-dc,chroma][dc,ac] |
192 | { 96, 110 }, { 96, 108 }, { 110, 115 } |
193 | }; |
194 | |
195 | // Sharpening by (slightly) raising the hi-frequency coeffs. |
196 | // Hack-ish but helpful for mid-bitrate range. Use with care. |
197 | #define SHARPEN_BITS 11 // number of descaling bits for sharpening bias |
198 | static const uint8_t kFreqSharpening[16] = { |
199 | 0, 30, 60, 90, |
200 | 30, 60, 90, 90, |
201 | 60, 90, 90, 90, |
202 | 90, 90, 90, 90 |
203 | }; |
204 | |
205 | //------------------------------------------------------------------------------ |
206 | // Initialize quantization parameters in VP8Matrix |
207 | |
208 | // Returns the average quantizer |
209 | static int ExpandMatrix(VP8Matrix* const m, int type) { |
210 | int i, sum; |
211 | for (i = 0; i < 2; ++i) { |
212 | const int is_ac_coeff = (i > 0); |
213 | const int bias = kBiasMatrices[type][is_ac_coeff]; |
214 | m->iq_[i] = (1 << QFIX) / m->q_[i]; |
215 | m->bias_[i] = BIAS(bias); |
216 | // zthresh_ is the exact value such that QUANTDIV(coeff, iQ, B) is: |
217 | // * zero if coeff <= zthresh |
218 | // * non-zero if coeff > zthresh |
219 | m->zthresh_[i] = ((1 << QFIX) - 1 - m->bias_[i]) / m->iq_[i]; |
220 | } |
221 | for (i = 2; i < 16; ++i) { |
222 | m->q_[i] = m->q_[1]; |
223 | m->iq_[i] = m->iq_[1]; |
224 | m->bias_[i] = m->bias_[1]; |
225 | m->zthresh_[i] = m->zthresh_[1]; |
226 | } |
227 | for (sum = 0, i = 0; i < 16; ++i) { |
228 | if (type == 0) { // we only use sharpening for AC luma coeffs |
229 | m->sharpen_[i] = (kFreqSharpening[i] * m->q_[i]) >> SHARPEN_BITS; |
230 | } else { |
231 | m->sharpen_[i] = 0; |
232 | } |
233 | sum += m->q_[i]; |
234 | } |
235 | return (sum + 8) >> 4; |
236 | } |
237 | |
238 | static void CheckLambdaValue(int* const v) { if (*v < 1) *v = 1; } |
239 | |
240 | static void SetupMatrices(VP8Encoder* enc) { |
241 | int i; |
242 | const int tlambda_scale = |
243 | (enc->method_ >= 4) ? enc->config_->sns_strength |
244 | : 0; |
245 | const int num_segments = enc->segment_hdr_.num_segments_; |
246 | for (i = 0; i < num_segments; ++i) { |
247 | VP8SegmentInfo* const m = &enc->dqm_[i]; |
248 | const int q = m->quant_; |
249 | int q_i4, q_i16, q_uv; |
250 | m->y1_.q_[0] = kDcTable[clip(q + enc->dq_y1_dc_, 0, 127)]; |
251 | m->y1_.q_[1] = kAcTable[clip(q, 0, 127)]; |
252 | |
253 | m->y2_.q_[0] = kDcTable[ clip(q + enc->dq_y2_dc_, 0, 127)] * 2; |
254 | m->y2_.q_[1] = kAcTable2[clip(q + enc->dq_y2_ac_, 0, 127)]; |
255 | |
256 | m->uv_.q_[0] = kDcTable[clip(q + enc->dq_uv_dc_, 0, 117)]; |
257 | m->uv_.q_[1] = kAcTable[clip(q + enc->dq_uv_ac_, 0, 127)]; |
258 | |
259 | q_i4 = ExpandMatrix(&m->y1_, 0); |
260 | q_i16 = ExpandMatrix(&m->y2_, 1); |
261 | q_uv = ExpandMatrix(&m->uv_, 2); |
262 | |
263 | m->lambda_i4_ = (3 * q_i4 * q_i4) >> 7; |
264 | m->lambda_i16_ = (3 * q_i16 * q_i16); |
265 | m->lambda_uv_ = (3 * q_uv * q_uv) >> 6; |
266 | m->lambda_mode_ = (1 * q_i4 * q_i4) >> 7; |
267 | m->lambda_trellis_i4_ = (7 * q_i4 * q_i4) >> 3; |
268 | m->lambda_trellis_i16_ = (q_i16 * q_i16) >> 2; |
269 | m->lambda_trellis_uv_ = (q_uv * q_uv) << 1; |
270 | m->tlambda_ = (tlambda_scale * q_i4) >> 5; |
271 | |
272 | // none of these constants should be < 1 |
273 | CheckLambdaValue(&m->lambda_i4_); |
274 | CheckLambdaValue(&m->lambda_i16_); |
275 | CheckLambdaValue(&m->lambda_uv_); |
276 | CheckLambdaValue(&m->lambda_mode_); |
277 | CheckLambdaValue(&m->lambda_trellis_i4_); |
278 | CheckLambdaValue(&m->lambda_trellis_i16_); |
279 | CheckLambdaValue(&m->lambda_trellis_uv_); |
280 | CheckLambdaValue(&m->tlambda_); |
281 | |
282 | m->min_disto_ = 20 * m->y1_.q_[0]; // quantization-aware min disto |
283 | m->max_edge_ = 0; |
284 | |
285 | m->i4_penalty_ = 1000 * q_i4 * q_i4; |
286 | } |
287 | } |
288 | |
289 | //------------------------------------------------------------------------------ |
290 | // Initialize filtering parameters |
291 | |
292 | // Very small filter-strength values have close to no visual effect. So we can |
293 | // save a little decoding-CPU by turning filtering off for these. |
294 | #define FSTRENGTH_CUTOFF 2 |
295 | |
296 | static void SetupFilterStrength(VP8Encoder* const enc) { |
297 | int i; |
298 | // level0 is in [0..500]. Using '-f 50' as filter_strength is mid-filtering. |
299 | const int level0 = 5 * enc->config_->filter_strength; |
300 | for (i = 0; i < NUM_MB_SEGMENTS; ++i) { |
301 | VP8SegmentInfo* const m = &enc->dqm_[i]; |
302 | // We focus on the quantization of AC coeffs. |
303 | const int qstep = kAcTable[clip(m->quant_, 0, 127)] >> 2; |
304 | const int base_strength = |
305 | VP8FilterStrengthFromDelta(enc->filter_hdr_.sharpness_, qstep); |
306 | // Segments with lower complexity ('beta') will be less filtered. |
307 | const int f = base_strength * level0 / (256 + m->beta_); |
308 | m->fstrength_ = (f < FSTRENGTH_CUTOFF) ? 0 : (f > 63) ? 63 : f; |
309 | } |
310 | // We record the initial strength (mainly for the case of 1-segment only). |
311 | enc->filter_hdr_.level_ = enc->dqm_[0].fstrength_; |
312 | enc->filter_hdr_.simple_ = (enc->config_->filter_type == 0); |
313 | enc->filter_hdr_.sharpness_ = enc->config_->filter_sharpness; |
314 | } |
315 | |
316 | //------------------------------------------------------------------------------ |
317 | |
318 | // Note: if you change the values below, remember that the max range |
319 | // allowed by the syntax for DQ_UV is [-16,16]. |
320 | #define MAX_DQ_UV (6) |
321 | #define MIN_DQ_UV (-4) |
322 | |
323 | // We want to emulate jpeg-like behaviour where the expected "good" quality |
324 | // is around q=75. Internally, our "good" middle is around c=50. So we |
325 | // map accordingly using linear piece-wise function |
326 | static double QualityToCompression(double c) { |
327 | const double linear_c = (c < 0.75) ? c * (2. / 3.) : 2. * c - 1.; |
328 | // The file size roughly scales as pow(quantizer, 3.). Actually, the |
329 | // exponent is somewhere between 2.8 and 3.2, but we're mostly interested |
330 | // in the mid-quant range. So we scale the compressibility inversely to |
331 | // this power-law: quant ~= compression ^ 1/3. This law holds well for |
332 | // low quant. Finer modeling for high-quant would make use of kAcTable[] |
333 | // more explicitly. |
334 | const double v = pow(linear_c, 1 / 3.); |
335 | return v; |
336 | } |
337 | |
338 | static double QualityToJPEGCompression(double c, double alpha) { |
339 | // We map the complexity 'alpha' and quality setting 'c' to a compression |
340 | // exponent empirically matched to the compression curve of libjpeg6b. |
341 | // On average, the WebP output size will be roughly similar to that of a |
342 | // JPEG file compressed with same quality factor. |
343 | const double amin = 0.30; |
344 | const double amax = 0.85; |
345 | const double exp_min = 0.4; |
346 | const double exp_max = 0.9; |
347 | const double slope = (exp_min - exp_max) / (amax - amin); |
348 | // Linearly interpolate 'expn' from exp_min to exp_max |
349 | // in the [amin, amax] range. |
350 | const double expn = (alpha > amax) ? exp_min |
351 | : (alpha < amin) ? exp_max |
352 | : exp_max + slope * (alpha - amin); |
353 | const double v = pow(c, expn); |
354 | return v; |
355 | } |
356 | |
357 | static int SegmentsAreEquivalent(const VP8SegmentInfo* const S1, |
358 | const VP8SegmentInfo* const S2) { |
359 | return (S1->quant_ == S2->quant_) && (S1->fstrength_ == S2->fstrength_); |
360 | } |
361 | |
362 | static void SimplifySegments(VP8Encoder* const enc) { |
363 | int map[NUM_MB_SEGMENTS] = { 0, 1, 2, 3 }; |
364 | // 'num_segments_' is previously validated and <= NUM_MB_SEGMENTS, but an |
365 | // explicit check is needed to avoid a spurious warning about 'i' exceeding |
366 | // array bounds of 'dqm_' with some compilers (noticed with gcc-4.9). |
367 | const int num_segments = (enc->segment_hdr_.num_segments_ < NUM_MB_SEGMENTS) |
368 | ? enc->segment_hdr_.num_segments_ |
369 | : NUM_MB_SEGMENTS; |
370 | int num_final_segments = 1; |
371 | int s1, s2; |
372 | for (s1 = 1; s1 < num_segments; ++s1) { // find similar segments |
373 | const VP8SegmentInfo* const S1 = &enc->dqm_[s1]; |
374 | int found = 0; |
375 | // check if we already have similar segment |
376 | for (s2 = 0; s2 < num_final_segments; ++s2) { |
377 | const VP8SegmentInfo* const S2 = &enc->dqm_[s2]; |
378 | if (SegmentsAreEquivalent(S1, S2)) { |
379 | found = 1; |
380 | break; |
381 | } |
382 | } |
383 | map[s1] = s2; |
384 | if (!found) { |
385 | if (num_final_segments != s1) { |
386 | enc->dqm_[num_final_segments] = enc->dqm_[s1]; |
387 | } |
388 | ++num_final_segments; |
389 | } |
390 | } |
391 | if (num_final_segments < num_segments) { // Remap |
392 | int i = enc->mb_w_ * enc->mb_h_; |
393 | while (i-- > 0) enc->mb_info_[i].segment_ = map[enc->mb_info_[i].segment_]; |
394 | enc->segment_hdr_.num_segments_ = num_final_segments; |
395 | // Replicate the trailing segment infos (it's mostly cosmetics) |
396 | for (i = num_final_segments; i < num_segments; ++i) { |
397 | enc->dqm_[i] = enc->dqm_[num_final_segments - 1]; |
398 | } |
399 | } |
400 | } |
401 | |
402 | void VP8SetSegmentParams(VP8Encoder* const enc, float quality) { |
403 | int i; |
404 | int dq_uv_ac, dq_uv_dc; |
405 | const int num_segments = enc->segment_hdr_.num_segments_; |
406 | const double amp = SNS_TO_DQ * enc->config_->sns_strength / 100. / 128.; |
407 | const double Q = quality / 100.; |
408 | const double c_base = enc->config_->emulate_jpeg_size ? |
409 | QualityToJPEGCompression(Q, enc->alpha_ / 255.) : |
410 | QualityToCompression(Q); |
411 | for (i = 0; i < num_segments; ++i) { |
412 | // We modulate the base coefficient to accommodate for the quantization |
413 | // susceptibility and allow denser segments to be quantized more. |
414 | const double expn = 1. - amp * enc->dqm_[i].alpha_; |
415 | const double c = pow(c_base, expn); |
416 | const int q = (int)(127. * (1. - c)); |
417 | assert(expn > 0.); |
418 | enc->dqm_[i].quant_ = clip(q, 0, 127); |
419 | } |
420 | |
421 | // purely indicative in the bitstream (except for the 1-segment case) |
422 | enc->base_quant_ = enc->dqm_[0].quant_; |
423 | |
424 | // fill-in values for the unused segments (required by the syntax) |
425 | for (i = num_segments; i < NUM_MB_SEGMENTS; ++i) { |
426 | enc->dqm_[i].quant_ = enc->base_quant_; |
427 | } |
428 | |
429 | // uv_alpha_ is normally spread around ~60. The useful range is |
430 | // typically ~30 (quite bad) to ~100 (ok to decimate UV more). |
431 | // We map it to the safe maximal range of MAX/MIN_DQ_UV for dq_uv. |
432 | dq_uv_ac = (enc->uv_alpha_ - MID_ALPHA) * (MAX_DQ_UV - MIN_DQ_UV) |
433 | / (MAX_ALPHA - MIN_ALPHA); |
434 | // we rescale by the user-defined strength of adaptation |
435 | dq_uv_ac = dq_uv_ac * enc->config_->sns_strength / 100; |
436 | // and make it safe. |
437 | dq_uv_ac = clip(dq_uv_ac, MIN_DQ_UV, MAX_DQ_UV); |
438 | // We also boost the dc-uv-quant a little, based on sns-strength, since |
439 | // U/V channels are quite more reactive to high quants (flat DC-blocks |
440 | // tend to appear, and are unpleasant). |
441 | dq_uv_dc = -4 * enc->config_->sns_strength / 100; |
442 | dq_uv_dc = clip(dq_uv_dc, -15, 15); // 4bit-signed max allowed |
443 | |
444 | enc->dq_y1_dc_ = 0; // TODO(skal): dq-lum |
445 | enc->dq_y2_dc_ = 0; |
446 | enc->dq_y2_ac_ = 0; |
447 | enc->dq_uv_dc_ = dq_uv_dc; |
448 | enc->dq_uv_ac_ = dq_uv_ac; |
449 | |
450 | SetupFilterStrength(enc); // initialize segments' filtering, eventually |
451 | |
452 | if (num_segments > 1) SimplifySegments(enc); |
453 | |
454 | SetupMatrices(enc); // finalize quantization matrices |
455 | } |
456 | |
457 | //------------------------------------------------------------------------------ |
458 | // Form the predictions in cache |
459 | |
460 | // Must be ordered using {DC_PRED, TM_PRED, V_PRED, H_PRED} as index |
461 | const uint16_t VP8I16ModeOffsets[4] = { I16DC16, I16TM16, I16VE16, I16HE16 }; |
462 | const uint16_t VP8UVModeOffsets[4] = { C8DC8, C8TM8, C8VE8, C8HE8 }; |
463 | |
464 | // Must be indexed using {B_DC_PRED -> B_HU_PRED} as index |
465 | const uint16_t VP8I4ModeOffsets[NUM_BMODES] = { |
466 | I4DC4, I4TM4, I4VE4, I4HE4, I4RD4, I4VR4, I4LD4, I4VL4, I4HD4, I4HU4 |
467 | }; |
468 | |
469 | void VP8MakeLuma16Preds(const VP8EncIterator* const it) { |
470 | const uint8_t* const left = it->x_ ? it->y_left_ : NULL; |
471 | const uint8_t* const top = it->y_ ? it->y_top_ : NULL; |
472 | VP8EncPredLuma16(it->yuv_p_, left, top); |
473 | } |
474 | |
475 | void VP8MakeChroma8Preds(const VP8EncIterator* const it) { |
476 | const uint8_t* const left = it->x_ ? it->u_left_ : NULL; |
477 | const uint8_t* const top = it->y_ ? it->uv_top_ : NULL; |
478 | VP8EncPredChroma8(it->yuv_p_, left, top); |
479 | } |
480 | |
481 | void VP8MakeIntra4Preds(const VP8EncIterator* const it) { |
482 | VP8EncPredLuma4(it->yuv_p_, it->i4_top_); |
483 | } |
484 | |
485 | //------------------------------------------------------------------------------ |
486 | // Quantize |
487 | |
488 | // Layout: |
489 | // +----+----+ |
490 | // |YYYY|UUVV| 0 |
491 | // |YYYY|UUVV| 4 |
492 | // |YYYY|....| 8 |
493 | // |YYYY|....| 12 |
494 | // +----+----+ |
495 | |
496 | const uint16_t VP8Scan[16] = { // Luma |
497 | 0 + 0 * BPS, 4 + 0 * BPS, 8 + 0 * BPS, 12 + 0 * BPS, |
498 | 0 + 4 * BPS, 4 + 4 * BPS, 8 + 4 * BPS, 12 + 4 * BPS, |
499 | 0 + 8 * BPS, 4 + 8 * BPS, 8 + 8 * BPS, 12 + 8 * BPS, |
500 | 0 + 12 * BPS, 4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS, |
501 | }; |
502 | |
503 | static const uint16_t VP8ScanUV[4 + 4] = { |
504 | 0 + 0 * BPS, 4 + 0 * BPS, 0 + 4 * BPS, 4 + 4 * BPS, // U |
505 | 8 + 0 * BPS, 12 + 0 * BPS, 8 + 4 * BPS, 12 + 4 * BPS // V |
506 | }; |
507 | |
508 | //------------------------------------------------------------------------------ |
509 | // Distortion measurement |
510 | |
511 | static const uint16_t kWeightY[16] = { |
512 | 38, 32, 20, 9, 32, 28, 17, 7, 20, 17, 10, 4, 9, 7, 4, 2 |
513 | }; |
514 | |
515 | static const uint16_t kWeightTrellis[16] = { |
516 | #if USE_TDISTO == 0 |
517 | 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16 |
518 | #else |
519 | 30, 27, 19, 11, |
520 | 27, 24, 17, 10, |
521 | 19, 17, 12, 8, |
522 | 11, 10, 8, 6 |
523 | #endif |
524 | }; |
525 | |
526 | // Init/Copy the common fields in score. |
527 | static void InitScore(VP8ModeScore* const rd) { |
528 | rd->D = 0; |
529 | rd->SD = 0; |
530 | rd->R = 0; |
531 | rd->H = 0; |
532 | rd->nz = 0; |
533 | rd->score = MAX_COST; |
534 | } |
535 | |
536 | static void CopyScore(VP8ModeScore* WEBP_RESTRICT const dst, |
537 | const VP8ModeScore* WEBP_RESTRICT const src) { |
538 | dst->D = src->D; |
539 | dst->SD = src->SD; |
540 | dst->R = src->R; |
541 | dst->H = src->H; |
542 | dst->nz = src->nz; // note that nz is not accumulated, but just copied. |
543 | dst->score = src->score; |
544 | } |
545 | |
546 | static void AddScore(VP8ModeScore* WEBP_RESTRICT const dst, |
547 | const VP8ModeScore* WEBP_RESTRICT const src) { |
548 | dst->D += src->D; |
549 | dst->SD += src->SD; |
550 | dst->R += src->R; |
551 | dst->H += src->H; |
552 | dst->nz |= src->nz; // here, new nz bits are accumulated. |
553 | dst->score += src->score; |
554 | } |
555 | |
556 | //------------------------------------------------------------------------------ |
557 | // Performs trellis-optimized quantization. |
558 | |
559 | // -- GODOT start -- |
560 | // Prevents Visual Studio debugger from using this Node struct in place of the Godot Node class. |
561 | #define Node Node_libwebp_quant |
562 | // -- GODOT end -- |
563 | |
564 | // Trellis node |
565 | typedef struct { |
566 | int8_t prev; // best previous node |
567 | int8_t sign; // sign of coeff_i |
568 | int16_t level; // level |
569 | } Node; |
570 | |
571 | // Score state |
572 | typedef struct { |
573 | score_t score; // partial RD score |
574 | const uint16_t* costs; // shortcut to cost tables |
575 | } ScoreState; |
576 | |
577 | // If a coefficient was quantized to a value Q (using a neutral bias), |
578 | // we test all alternate possibilities between [Q-MIN_DELTA, Q+MAX_DELTA] |
579 | // We don't test negative values though. |
580 | #define MIN_DELTA 0 // how much lower level to try |
581 | #define MAX_DELTA 1 // how much higher |
582 | #define NUM_NODES (MIN_DELTA + 1 + MAX_DELTA) |
583 | #define NODE(n, l) (nodes[(n)][(l) + MIN_DELTA]) |
584 | #define SCORE_STATE(n, l) (score_states[n][(l) + MIN_DELTA]) |
585 | |
586 | static WEBP_INLINE void SetRDScore(int lambda, VP8ModeScore* const rd) { |
587 | rd->score = (rd->R + rd->H) * lambda + RD_DISTO_MULT * (rd->D + rd->SD); |
588 | } |
589 | |
590 | static WEBP_INLINE score_t RDScoreTrellis(int lambda, score_t rate, |
591 | score_t distortion) { |
592 | return rate * lambda + RD_DISTO_MULT * distortion; |
593 | } |
594 | |
595 | // Coefficient type. |
596 | enum { TYPE_I16_AC = 0, TYPE_I16_DC = 1, TYPE_CHROMA_A = 2, TYPE_I4_AC = 3 }; |
597 | |
598 | static int TrellisQuantizeBlock(const VP8Encoder* WEBP_RESTRICT const enc, |
599 | int16_t in[16], int16_t out[16], |
600 | int ctx0, int coeff_type, |
601 | const VP8Matrix* WEBP_RESTRICT const mtx, |
602 | int lambda) { |
603 | const ProbaArray* const probas = enc->proba_.coeffs_[coeff_type]; |
604 | CostArrayPtr const costs = |
605 | (CostArrayPtr)enc->proba_.remapped_costs_[coeff_type]; |
606 | const int first = (coeff_type == TYPE_I16_AC) ? 1 : 0; |
607 | Node nodes[16][NUM_NODES]; |
608 | ScoreState score_states[2][NUM_NODES]; |
609 | ScoreState* ss_cur = &SCORE_STATE(0, MIN_DELTA); |
610 | ScoreState* ss_prev = &SCORE_STATE(1, MIN_DELTA); |
611 | int best_path[3] = {-1, -1, -1}; // store best-last/best-level/best-previous |
612 | score_t best_score; |
613 | int n, m, p, last; |
614 | |
615 | { |
616 | score_t cost; |
617 | const int thresh = mtx->q_[1] * mtx->q_[1] / 4; |
618 | const int last_proba = probas[VP8EncBands[first]][ctx0][0]; |
619 | |
620 | // compute the position of the last interesting coefficient |
621 | last = first - 1; |
622 | for (n = 15; n >= first; --n) { |
623 | const int j = kZigzag[n]; |
624 | const int err = in[j] * in[j]; |
625 | if (err > thresh) { |
626 | last = n; |
627 | break; |
628 | } |
629 | } |
630 | // we don't need to go inspect up to n = 16 coeffs. We can just go up |
631 | // to last + 1 (inclusive) without losing much. |
632 | if (last < 15) ++last; |
633 | |
634 | // compute 'skip' score. This is the max score one can do. |
635 | cost = VP8BitCost(0, last_proba); |
636 | best_score = RDScoreTrellis(lambda, cost, 0); |
637 | |
638 | // initialize source node. |
639 | for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { |
640 | const score_t rate = (ctx0 == 0) ? VP8BitCost(1, last_proba) : 0; |
641 | ss_cur[m].score = RDScoreTrellis(lambda, rate, 0); |
642 | ss_cur[m].costs = costs[first][ctx0]; |
643 | } |
644 | } |
645 | |
646 | // traverse trellis. |
647 | for (n = first; n <= last; ++n) { |
648 | const int j = kZigzag[n]; |
649 | const uint32_t Q = mtx->q_[j]; |
650 | const uint32_t iQ = mtx->iq_[j]; |
651 | const uint32_t B = BIAS(0x00); // neutral bias |
652 | // note: it's important to take sign of the _original_ coeff, |
653 | // so we don't have to consider level < 0 afterward. |
654 | const int sign = (in[j] < 0); |
655 | const uint32_t coeff0 = (sign ? -in[j] : in[j]) + mtx->sharpen_[j]; |
656 | int level0 = QUANTDIV(coeff0, iQ, B); |
657 | int thresh_level = QUANTDIV(coeff0, iQ, BIAS(0x80)); |
658 | if (thresh_level > MAX_LEVEL) thresh_level = MAX_LEVEL; |
659 | if (level0 > MAX_LEVEL) level0 = MAX_LEVEL; |
660 | |
661 | { // Swap current and previous score states |
662 | ScoreState* const tmp = ss_cur; |
663 | ss_cur = ss_prev; |
664 | ss_prev = tmp; |
665 | } |
666 | |
667 | // test all alternate level values around level0. |
668 | for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { |
669 | Node* const cur = &NODE(n, m); |
670 | const int level = level0 + m; |
671 | const int ctx = (level > 2) ? 2 : level; |
672 | const int band = VP8EncBands[n + 1]; |
673 | score_t base_score; |
674 | score_t best_cur_score; |
675 | int best_prev; |
676 | score_t cost, score; |
677 | |
678 | ss_cur[m].costs = costs[n + 1][ctx]; |
679 | if (level < 0 || level > thresh_level) { |
680 | ss_cur[m].score = MAX_COST; |
681 | // Node is dead. |
682 | continue; |
683 | } |
684 | |
685 | { |
686 | // Compute delta_error = how much coding this level will |
687 | // subtract to max_error as distortion. |
688 | // Here, distortion = sum of (|coeff_i| - level_i * Q_i)^2 |
689 | const int new_error = coeff0 - level * Q; |
690 | const int delta_error = |
691 | kWeightTrellis[j] * (new_error * new_error - coeff0 * coeff0); |
692 | base_score = RDScoreTrellis(lambda, 0, delta_error); |
693 | } |
694 | |
695 | // Inspect all possible non-dead predecessors. Retain only the best one. |
696 | // The base_score is added to all scores so it is only added for the final |
697 | // value after the loop. |
698 | cost = VP8LevelCost(ss_prev[-MIN_DELTA].costs, level); |
699 | best_cur_score = |
700 | ss_prev[-MIN_DELTA].score + RDScoreTrellis(lambda, cost, 0); |
701 | best_prev = -MIN_DELTA; |
702 | for (p = -MIN_DELTA + 1; p <= MAX_DELTA; ++p) { |
703 | // Dead nodes (with ss_prev[p].score >= MAX_COST) are automatically |
704 | // eliminated since their score can't be better than the current best. |
705 | cost = VP8LevelCost(ss_prev[p].costs, level); |
706 | // Examine node assuming it's a non-terminal one. |
707 | score = ss_prev[p].score + RDScoreTrellis(lambda, cost, 0); |
708 | if (score < best_cur_score) { |
709 | best_cur_score = score; |
710 | best_prev = p; |
711 | } |
712 | } |
713 | best_cur_score += base_score; |
714 | // Store best finding in current node. |
715 | cur->sign = sign; |
716 | cur->level = level; |
717 | cur->prev = best_prev; |
718 | ss_cur[m].score = best_cur_score; |
719 | |
720 | // Now, record best terminal node (and thus best entry in the graph). |
721 | if (level != 0 && best_cur_score < best_score) { |
722 | const score_t last_pos_cost = |
723 | (n < 15) ? VP8BitCost(0, probas[band][ctx][0]) : 0; |
724 | const score_t last_pos_score = RDScoreTrellis(lambda, last_pos_cost, 0); |
725 | score = best_cur_score + last_pos_score; |
726 | if (score < best_score) { |
727 | best_score = score; |
728 | best_path[0] = n; // best eob position |
729 | best_path[1] = m; // best node index |
730 | best_path[2] = best_prev; // best predecessor |
731 | } |
732 | } |
733 | } |
734 | } |
735 | |
736 | // Fresh start |
737 | // Beware! We must preserve in[0]/out[0] value for TYPE_I16_AC case. |
738 | if (coeff_type == TYPE_I16_AC) { |
739 | memset(in + 1, 0, 15 * sizeof(*in)); |
740 | memset(out + 1, 0, 15 * sizeof(*out)); |
741 | } else { |
742 | memset(in, 0, 16 * sizeof(*in)); |
743 | memset(out, 0, 16 * sizeof(*out)); |
744 | } |
745 | if (best_path[0] == -1) { |
746 | return 0; // skip! |
747 | } |
748 | |
749 | { |
750 | // Unwind the best path. |
751 | // Note: best-prev on terminal node is not necessarily equal to the |
752 | // best_prev for non-terminal. So we patch best_path[2] in. |
753 | int nz = 0; |
754 | int best_node = best_path[1]; |
755 | n = best_path[0]; |
756 | NODE(n, best_node).prev = best_path[2]; // force best-prev for terminal |
757 | |
758 | for (; n >= first; --n) { |
759 | const Node* const node = &NODE(n, best_node); |
760 | const int j = kZigzag[n]; |
761 | out[n] = node->sign ? -node->level : node->level; |
762 | nz |= node->level; |
763 | in[j] = out[n] * mtx->q_[j]; |
764 | best_node = node->prev; |
765 | } |
766 | return (nz != 0); |
767 | } |
768 | } |
769 | |
770 | #undef NODE |
771 | |
772 | //------------------------------------------------------------------------------ |
773 | // Performs: difference, transform, quantize, back-transform, add |
774 | // all at once. Output is the reconstructed block in *yuv_out, and the |
775 | // quantized levels in *levels. |
776 | |
777 | static int ReconstructIntra16(VP8EncIterator* WEBP_RESTRICT const it, |
778 | VP8ModeScore* WEBP_RESTRICT const rd, |
779 | uint8_t* WEBP_RESTRICT const yuv_out, |
780 | int mode) { |
781 | const VP8Encoder* const enc = it->enc_; |
782 | const uint8_t* const ref = it->yuv_p_ + VP8I16ModeOffsets[mode]; |
783 | const uint8_t* const src = it->yuv_in_ + Y_OFF_ENC; |
784 | const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; |
785 | int nz = 0; |
786 | int n; |
787 | int16_t tmp[16][16], dc_tmp[16]; |
788 | |
789 | for (n = 0; n < 16; n += 2) { |
790 | VP8FTransform2(src + VP8Scan[n], ref + VP8Scan[n], tmp[n]); |
791 | } |
792 | VP8FTransformWHT(tmp[0], dc_tmp); |
793 | nz |= VP8EncQuantizeBlockWHT(dc_tmp, rd->y_dc_levels, &dqm->y2_) << 24; |
794 | |
795 | if (DO_TRELLIS_I16 && it->do_trellis_) { |
796 | int x, y; |
797 | VP8IteratorNzToBytes(it); |
798 | for (y = 0, n = 0; y < 4; ++y) { |
799 | for (x = 0; x < 4; ++x, ++n) { |
800 | const int ctx = it->top_nz_[x] + it->left_nz_[y]; |
801 | const int non_zero = TrellisQuantizeBlock( |
802 | enc, tmp[n], rd->y_ac_levels[n], ctx, TYPE_I16_AC, &dqm->y1_, |
803 | dqm->lambda_trellis_i16_); |
804 | it->top_nz_[x] = it->left_nz_[y] = non_zero; |
805 | rd->y_ac_levels[n][0] = 0; |
806 | nz |= non_zero << n; |
807 | } |
808 | } |
809 | } else { |
810 | for (n = 0; n < 16; n += 2) { |
811 | // Zero-out the first coeff, so that: a) nz is correct below, and |
812 | // b) finding 'last' non-zero coeffs in SetResidualCoeffs() is simplified. |
813 | tmp[n][0] = tmp[n + 1][0] = 0; |
814 | nz |= VP8EncQuantize2Blocks(tmp[n], rd->y_ac_levels[n], &dqm->y1_) << n; |
815 | assert(rd->y_ac_levels[n + 0][0] == 0); |
816 | assert(rd->y_ac_levels[n + 1][0] == 0); |
817 | } |
818 | } |
819 | |
820 | // Transform back |
821 | VP8TransformWHT(dc_tmp, tmp[0]); |
822 | for (n = 0; n < 16; n += 2) { |
823 | VP8ITransform(ref + VP8Scan[n], tmp[n], yuv_out + VP8Scan[n], 1); |
824 | } |
825 | |
826 | return nz; |
827 | } |
828 | |
829 | static int ReconstructIntra4(VP8EncIterator* WEBP_RESTRICT const it, |
830 | int16_t levels[16], |
831 | const uint8_t* WEBP_RESTRICT const src, |
832 | uint8_t* WEBP_RESTRICT const yuv_out, |
833 | int mode) { |
834 | const VP8Encoder* const enc = it->enc_; |
835 | const uint8_t* const ref = it->yuv_p_ + VP8I4ModeOffsets[mode]; |
836 | const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; |
837 | int nz = 0; |
838 | int16_t tmp[16]; |
839 | |
840 | VP8FTransform(src, ref, tmp); |
841 | if (DO_TRELLIS_I4 && it->do_trellis_) { |
842 | const int x = it->i4_ & 3, y = it->i4_ >> 2; |
843 | const int ctx = it->top_nz_[x] + it->left_nz_[y]; |
844 | nz = TrellisQuantizeBlock(enc, tmp, levels, ctx, TYPE_I4_AC, &dqm->y1_, |
845 | dqm->lambda_trellis_i4_); |
846 | } else { |
847 | nz = VP8EncQuantizeBlock(tmp, levels, &dqm->y1_); |
848 | } |
849 | VP8ITransform(ref, tmp, yuv_out, 0); |
850 | return nz; |
851 | } |
852 | |
853 | //------------------------------------------------------------------------------ |
854 | // DC-error diffusion |
855 | |
856 | // Diffusion weights. We under-correct a bit (15/16th of the error is actually |
857 | // diffused) to avoid 'rainbow' chessboard pattern of blocks at q~=0. |
858 | #define C1 7 // fraction of error sent to the 4x4 block below |
859 | #define C2 8 // fraction of error sent to the 4x4 block on the right |
860 | #define DSHIFT 4 |
861 | #define DSCALE 1 // storage descaling, needed to make the error fit int8_t |
862 | |
863 | // Quantize as usual, but also compute and return the quantization error. |
864 | // Error is already divided by DSHIFT. |
865 | static int QuantizeSingle(int16_t* WEBP_RESTRICT const v, |
866 | const VP8Matrix* WEBP_RESTRICT const mtx) { |
867 | int V = *v; |
868 | const int sign = (V < 0); |
869 | if (sign) V = -V; |
870 | if (V > (int)mtx->zthresh_[0]) { |
871 | const int qV = QUANTDIV(V, mtx->iq_[0], mtx->bias_[0]) * mtx->q_[0]; |
872 | const int err = (V - qV); |
873 | *v = sign ? -qV : qV; |
874 | return (sign ? -err : err) >> DSCALE; |
875 | } |
876 | *v = 0; |
877 | return (sign ? -V : V) >> DSCALE; |
878 | } |
879 | |
880 | static void CorrectDCValues(const VP8EncIterator* WEBP_RESTRICT const it, |
881 | const VP8Matrix* WEBP_RESTRICT const mtx, |
882 | int16_t tmp[][16], |
883 | VP8ModeScore* WEBP_RESTRICT const rd) { |
884 | // | top[0] | top[1] |
885 | // --------+--------+--------- |
886 | // left[0] | tmp[0] tmp[1] <-> err0 err1 |
887 | // left[1] | tmp[2] tmp[3] err2 err3 |
888 | // |
889 | // Final errors {err1,err2,err3} are preserved and later restored |
890 | // as top[]/left[] on the next block. |
891 | int ch; |
892 | for (ch = 0; ch <= 1; ++ch) { |
893 | const int8_t* const top = it->top_derr_[it->x_][ch]; |
894 | const int8_t* const left = it->left_derr_[ch]; |
895 | int16_t (* const c)[16] = &tmp[ch * 4]; |
896 | int err0, err1, err2, err3; |
897 | c[0][0] += (C1 * top[0] + C2 * left[0]) >> (DSHIFT - DSCALE); |
898 | err0 = QuantizeSingle(&c[0][0], mtx); |
899 | c[1][0] += (C1 * top[1] + C2 * err0) >> (DSHIFT - DSCALE); |
900 | err1 = QuantizeSingle(&c[1][0], mtx); |
901 | c[2][0] += (C1 * err0 + C2 * left[1]) >> (DSHIFT - DSCALE); |
902 | err2 = QuantizeSingle(&c[2][0], mtx); |
903 | c[3][0] += (C1 * err1 + C2 * err2) >> (DSHIFT - DSCALE); |
904 | err3 = QuantizeSingle(&c[3][0], mtx); |
905 | // error 'err' is bounded by mtx->q_[0] which is 132 at max. Hence |
906 | // err >> DSCALE will fit in an int8_t type if DSCALE>=1. |
907 | assert(abs(err1) <= 127 && abs(err2) <= 127 && abs(err3) <= 127); |
908 | rd->derr[ch][0] = (int8_t)err1; |
909 | rd->derr[ch][1] = (int8_t)err2; |
910 | rd->derr[ch][2] = (int8_t)err3; |
911 | } |
912 | } |
913 | |
914 | static void StoreDiffusionErrors(VP8EncIterator* WEBP_RESTRICT const it, |
915 | const VP8ModeScore* WEBP_RESTRICT const rd) { |
916 | int ch; |
917 | for (ch = 0; ch <= 1; ++ch) { |
918 | int8_t* const top = it->top_derr_[it->x_][ch]; |
919 | int8_t* const left = it->left_derr_[ch]; |
920 | left[0] = rd->derr[ch][0]; // restore err1 |
921 | left[1] = 3 * rd->derr[ch][2] >> 2; // ... 3/4th of err3 |
922 | top[0] = rd->derr[ch][1]; // ... err2 |
923 | top[1] = rd->derr[ch][2] - left[1]; // ... 1/4th of err3. |
924 | } |
925 | } |
926 | |
927 | #undef C1 |
928 | #undef C2 |
929 | #undef DSHIFT |
930 | #undef DSCALE |
931 | |
932 | //------------------------------------------------------------------------------ |
933 | |
934 | static int ReconstructUV(VP8EncIterator* WEBP_RESTRICT const it, |
935 | VP8ModeScore* WEBP_RESTRICT const rd, |
936 | uint8_t* WEBP_RESTRICT const yuv_out, int mode) { |
937 | const VP8Encoder* const enc = it->enc_; |
938 | const uint8_t* const ref = it->yuv_p_ + VP8UVModeOffsets[mode]; |
939 | const uint8_t* const src = it->yuv_in_ + U_OFF_ENC; |
940 | const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; |
941 | int nz = 0; |
942 | int n; |
943 | int16_t tmp[8][16]; |
944 | |
945 | for (n = 0; n < 8; n += 2) { |
946 | VP8FTransform2(src + VP8ScanUV[n], ref + VP8ScanUV[n], tmp[n]); |
947 | } |
948 | if (it->top_derr_ != NULL) CorrectDCValues(it, &dqm->uv_, tmp, rd); |
949 | |
950 | if (DO_TRELLIS_UV && it->do_trellis_) { |
951 | int ch, x, y; |
952 | for (ch = 0, n = 0; ch <= 2; ch += 2) { |
953 | for (y = 0; y < 2; ++y) { |
954 | for (x = 0; x < 2; ++x, ++n) { |
955 | const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y]; |
956 | const int non_zero = TrellisQuantizeBlock( |
957 | enc, tmp[n], rd->uv_levels[n], ctx, TYPE_CHROMA_A, &dqm->uv_, |
958 | dqm->lambda_trellis_uv_); |
959 | it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] = non_zero; |
960 | nz |= non_zero << n; |
961 | } |
962 | } |
963 | } |
964 | } else { |
965 | for (n = 0; n < 8; n += 2) { |
966 | nz |= VP8EncQuantize2Blocks(tmp[n], rd->uv_levels[n], &dqm->uv_) << n; |
967 | } |
968 | } |
969 | |
970 | for (n = 0; n < 8; n += 2) { |
971 | VP8ITransform(ref + VP8ScanUV[n], tmp[n], yuv_out + VP8ScanUV[n], 1); |
972 | } |
973 | return (nz << 16); |
974 | } |
975 | |
976 | //------------------------------------------------------------------------------ |
977 | // RD-opt decision. Reconstruct each modes, evalue distortion and bit-cost. |
978 | // Pick the mode is lower RD-cost = Rate + lambda * Distortion. |
979 | |
980 | static void StoreMaxDelta(VP8SegmentInfo* const dqm, const int16_t DCs[16]) { |
981 | // We look at the first three AC coefficients to determine what is the average |
982 | // delta between each sub-4x4 block. |
983 | const int v0 = abs(DCs[1]); |
984 | const int v1 = abs(DCs[2]); |
985 | const int v2 = abs(DCs[4]); |
986 | int max_v = (v1 > v0) ? v1 : v0; |
987 | max_v = (v2 > max_v) ? v2 : max_v; |
988 | if (max_v > dqm->max_edge_) dqm->max_edge_ = max_v; |
989 | } |
990 | |
991 | static void SwapModeScore(VP8ModeScore** a, VP8ModeScore** b) { |
992 | VP8ModeScore* const tmp = *a; |
993 | *a = *b; |
994 | *b = tmp; |
995 | } |
996 | |
997 | static void SwapPtr(uint8_t** a, uint8_t** b) { |
998 | uint8_t* const tmp = *a; |
999 | *a = *b; |
1000 | *b = tmp; |
1001 | } |
1002 | |
1003 | static void SwapOut(VP8EncIterator* const it) { |
1004 | SwapPtr(&it->yuv_out_, &it->yuv_out2_); |
1005 | } |
1006 | |
1007 | static void PickBestIntra16(VP8EncIterator* WEBP_RESTRICT const it, |
1008 | VP8ModeScore* WEBP_RESTRICT rd) { |
1009 | const int kNumBlocks = 16; |
1010 | VP8SegmentInfo* const dqm = &it->enc_->dqm_[it->mb_->segment_]; |
1011 | const int lambda = dqm->lambda_i16_; |
1012 | const int tlambda = dqm->tlambda_; |
1013 | const uint8_t* const src = it->yuv_in_ + Y_OFF_ENC; |
1014 | VP8ModeScore rd_tmp; |
1015 | VP8ModeScore* rd_cur = &rd_tmp; |
1016 | VP8ModeScore* rd_best = rd; |
1017 | int mode; |
1018 | int is_flat = IsFlatSource16(it->yuv_in_ + Y_OFF_ENC); |
1019 | |
1020 | rd->mode_i16 = -1; |
1021 | for (mode = 0; mode < NUM_PRED_MODES; ++mode) { |
1022 | uint8_t* const tmp_dst = it->yuv_out2_ + Y_OFF_ENC; // scratch buffer |
1023 | rd_cur->mode_i16 = mode; |
1024 | |
1025 | // Reconstruct |
1026 | rd_cur->nz = ReconstructIntra16(it, rd_cur, tmp_dst, mode); |
1027 | |
1028 | // Measure RD-score |
1029 | rd_cur->D = VP8SSE16x16(src, tmp_dst); |
1030 | rd_cur->SD = |
1031 | tlambda ? MULT_8B(tlambda, VP8TDisto16x16(src, tmp_dst, kWeightY)) : 0; |
1032 | rd_cur->H = VP8FixedCostsI16[mode]; |
1033 | rd_cur->R = VP8GetCostLuma16(it, rd_cur); |
1034 | if (is_flat) { |
1035 | // refine the first impression (which was in pixel space) |
1036 | is_flat = IsFlat(rd_cur->y_ac_levels[0], kNumBlocks, FLATNESS_LIMIT_I16); |
1037 | if (is_flat) { |
1038 | // Block is very flat. We put emphasis on the distortion being very low! |
1039 | rd_cur->D *= 2; |
1040 | rd_cur->SD *= 2; |
1041 | } |
1042 | } |
1043 | |
1044 | // Since we always examine Intra16 first, we can overwrite *rd directly. |
1045 | SetRDScore(lambda, rd_cur); |
1046 | if (mode == 0 || rd_cur->score < rd_best->score) { |
1047 | SwapModeScore(&rd_cur, &rd_best); |
1048 | SwapOut(it); |
1049 | } |
1050 | } |
1051 | if (rd_best != rd) { |
1052 | memcpy(rd, rd_best, sizeof(*rd)); |
1053 | } |
1054 | SetRDScore(dqm->lambda_mode_, rd); // finalize score for mode decision. |
1055 | VP8SetIntra16Mode(it, rd->mode_i16); |
1056 | |
1057 | // we have a blocky macroblock (only DCs are non-zero) with fairly high |
1058 | // distortion, record max delta so we can later adjust the minimal filtering |
1059 | // strength needed to smooth these blocks out. |
1060 | if ((rd->nz & 0x100ffff) == 0x1000000 && rd->D > dqm->min_disto_) { |
1061 | StoreMaxDelta(dqm, rd->y_dc_levels); |
1062 | } |
1063 | } |
1064 | |
1065 | //------------------------------------------------------------------------------ |
1066 | |
1067 | // return the cost array corresponding to the surrounding prediction modes. |
1068 | static const uint16_t* GetCostModeI4(VP8EncIterator* WEBP_RESTRICT const it, |
1069 | const uint8_t modes[16]) { |
1070 | const int preds_w = it->enc_->preds_w_; |
1071 | const int x = (it->i4_ & 3), y = it->i4_ >> 2; |
1072 | const int left = (x == 0) ? it->preds_[y * preds_w - 1] : modes[it->i4_ - 1]; |
1073 | const int top = (y == 0) ? it->preds_[-preds_w + x] : modes[it->i4_ - 4]; |
1074 | return VP8FixedCostsI4[top][left]; |
1075 | } |
1076 | |
1077 | static int PickBestIntra4(VP8EncIterator* WEBP_RESTRICT const it, |
1078 | VP8ModeScore* WEBP_RESTRICT const rd) { |
1079 | const VP8Encoder* const enc = it->enc_; |
1080 | const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; |
1081 | const int lambda = dqm->lambda_i4_; |
1082 | const int tlambda = dqm->tlambda_; |
1083 | const uint8_t* const src0 = it->yuv_in_ + Y_OFF_ENC; |
1084 | uint8_t* const best_blocks = it->yuv_out2_ + Y_OFF_ENC; |
1085 | int = 0; |
1086 | VP8ModeScore rd_best; |
1087 | |
1088 | if (enc->max_i4_header_bits_ == 0) { |
1089 | return 0; |
1090 | } |
1091 | |
1092 | InitScore(&rd_best); |
1093 | rd_best.H = 211; // '211' is the value of VP8BitCost(0, 145) |
1094 | SetRDScore(dqm->lambda_mode_, &rd_best); |
1095 | VP8IteratorStartI4(it); |
1096 | do { |
1097 | const int kNumBlocks = 1; |
1098 | VP8ModeScore rd_i4; |
1099 | int mode; |
1100 | int best_mode = -1; |
1101 | const uint8_t* const src = src0 + VP8Scan[it->i4_]; |
1102 | const uint16_t* const mode_costs = GetCostModeI4(it, rd->modes_i4); |
1103 | uint8_t* best_block = best_blocks + VP8Scan[it->i4_]; |
1104 | uint8_t* tmp_dst = it->yuv_p_ + I4TMP; // scratch buffer. |
1105 | |
1106 | InitScore(&rd_i4); |
1107 | VP8MakeIntra4Preds(it); |
1108 | for (mode = 0; mode < NUM_BMODES; ++mode) { |
1109 | VP8ModeScore rd_tmp; |
1110 | int16_t tmp_levels[16]; |
1111 | |
1112 | // Reconstruct |
1113 | rd_tmp.nz = |
1114 | ReconstructIntra4(it, tmp_levels, src, tmp_dst, mode) << it->i4_; |
1115 | |
1116 | // Compute RD-score |
1117 | rd_tmp.D = VP8SSE4x4(src, tmp_dst); |
1118 | rd_tmp.SD = |
1119 | tlambda ? MULT_8B(tlambda, VP8TDisto4x4(src, tmp_dst, kWeightY)) |
1120 | : 0; |
1121 | rd_tmp.H = mode_costs[mode]; |
1122 | |
1123 | // Add flatness penalty, to avoid flat area to be mispredicted |
1124 | // by a complex mode. |
1125 | if (mode > 0 && IsFlat(tmp_levels, kNumBlocks, FLATNESS_LIMIT_I4)) { |
1126 | rd_tmp.R = FLATNESS_PENALTY * kNumBlocks; |
1127 | } else { |
1128 | rd_tmp.R = 0; |
1129 | } |
1130 | |
1131 | // early-out check |
1132 | SetRDScore(lambda, &rd_tmp); |
1133 | if (best_mode >= 0 && rd_tmp.score >= rd_i4.score) continue; |
1134 | |
1135 | // finish computing score |
1136 | rd_tmp.R += VP8GetCostLuma4(it, tmp_levels); |
1137 | SetRDScore(lambda, &rd_tmp); |
1138 | |
1139 | if (best_mode < 0 || rd_tmp.score < rd_i4.score) { |
1140 | CopyScore(&rd_i4, &rd_tmp); |
1141 | best_mode = mode; |
1142 | SwapPtr(&tmp_dst, &best_block); |
1143 | memcpy(rd_best.y_ac_levels[it->i4_], tmp_levels, |
1144 | sizeof(rd_best.y_ac_levels[it->i4_])); |
1145 | } |
1146 | } |
1147 | SetRDScore(dqm->lambda_mode_, &rd_i4); |
1148 | AddScore(&rd_best, &rd_i4); |
1149 | if (rd_best.score >= rd->score) { |
1150 | return 0; |
1151 | } |
1152 | total_header_bits += (int)rd_i4.H; // <- equal to mode_costs[best_mode]; |
1153 | if (total_header_bits > enc->max_i4_header_bits_) { |
1154 | return 0; |
1155 | } |
1156 | // Copy selected samples if not in the right place already. |
1157 | if (best_block != best_blocks + VP8Scan[it->i4_]) { |
1158 | VP8Copy4x4(best_block, best_blocks + VP8Scan[it->i4_]); |
1159 | } |
1160 | rd->modes_i4[it->i4_] = best_mode; |
1161 | it->top_nz_[it->i4_ & 3] = it->left_nz_[it->i4_ >> 2] = (rd_i4.nz ? 1 : 0); |
1162 | } while (VP8IteratorRotateI4(it, best_blocks)); |
1163 | |
1164 | // finalize state |
1165 | CopyScore(rd, &rd_best); |
1166 | VP8SetIntra4Mode(it, rd->modes_i4); |
1167 | SwapOut(it); |
1168 | memcpy(rd->y_ac_levels, rd_best.y_ac_levels, sizeof(rd->y_ac_levels)); |
1169 | return 1; // select intra4x4 over intra16x16 |
1170 | } |
1171 | |
1172 | //------------------------------------------------------------------------------ |
1173 | |
1174 | static void PickBestUV(VP8EncIterator* WEBP_RESTRICT const it, |
1175 | VP8ModeScore* WEBP_RESTRICT const rd) { |
1176 | const int kNumBlocks = 8; |
1177 | const VP8SegmentInfo* const dqm = &it->enc_->dqm_[it->mb_->segment_]; |
1178 | const int lambda = dqm->lambda_uv_; |
1179 | const uint8_t* const src = it->yuv_in_ + U_OFF_ENC; |
1180 | uint8_t* tmp_dst = it->yuv_out2_ + U_OFF_ENC; // scratch buffer |
1181 | uint8_t* dst0 = it->yuv_out_ + U_OFF_ENC; |
1182 | uint8_t* dst = dst0; |
1183 | VP8ModeScore rd_best; |
1184 | int mode; |
1185 | |
1186 | rd->mode_uv = -1; |
1187 | InitScore(&rd_best); |
1188 | for (mode = 0; mode < NUM_PRED_MODES; ++mode) { |
1189 | VP8ModeScore rd_uv; |
1190 | |
1191 | // Reconstruct |
1192 | rd_uv.nz = ReconstructUV(it, &rd_uv, tmp_dst, mode); |
1193 | |
1194 | // Compute RD-score |
1195 | rd_uv.D = VP8SSE16x8(src, tmp_dst); |
1196 | rd_uv.SD = 0; // not calling TDisto here: it tends to flatten areas. |
1197 | rd_uv.H = VP8FixedCostsUV[mode]; |
1198 | rd_uv.R = VP8GetCostUV(it, &rd_uv); |
1199 | if (mode > 0 && IsFlat(rd_uv.uv_levels[0], kNumBlocks, FLATNESS_LIMIT_UV)) { |
1200 | rd_uv.R += FLATNESS_PENALTY * kNumBlocks; |
1201 | } |
1202 | |
1203 | SetRDScore(lambda, &rd_uv); |
1204 | if (mode == 0 || rd_uv.score < rd_best.score) { |
1205 | CopyScore(&rd_best, &rd_uv); |
1206 | rd->mode_uv = mode; |
1207 | memcpy(rd->uv_levels, rd_uv.uv_levels, sizeof(rd->uv_levels)); |
1208 | if (it->top_derr_ != NULL) { |
1209 | memcpy(rd->derr, rd_uv.derr, sizeof(rd_uv.derr)); |
1210 | } |
1211 | SwapPtr(&dst, &tmp_dst); |
1212 | } |
1213 | } |
1214 | VP8SetIntraUVMode(it, rd->mode_uv); |
1215 | AddScore(rd, &rd_best); |
1216 | if (dst != dst0) { // copy 16x8 block if needed |
1217 | VP8Copy16x8(dst, dst0); |
1218 | } |
1219 | if (it->top_derr_ != NULL) { // store diffusion errors for next block |
1220 | StoreDiffusionErrors(it, rd); |
1221 | } |
1222 | } |
1223 | |
1224 | //------------------------------------------------------------------------------ |
1225 | // Final reconstruction and quantization. |
1226 | |
1227 | static void SimpleQuantize(VP8EncIterator* WEBP_RESTRICT const it, |
1228 | VP8ModeScore* WEBP_RESTRICT const rd) { |
1229 | const VP8Encoder* const enc = it->enc_; |
1230 | const int is_i16 = (it->mb_->type_ == 1); |
1231 | int nz = 0; |
1232 | |
1233 | if (is_i16) { |
1234 | nz = ReconstructIntra16(it, rd, it->yuv_out_ + Y_OFF_ENC, it->preds_[0]); |
1235 | } else { |
1236 | VP8IteratorStartI4(it); |
1237 | do { |
1238 | const int mode = |
1239 | it->preds_[(it->i4_ & 3) + (it->i4_ >> 2) * enc->preds_w_]; |
1240 | const uint8_t* const src = it->yuv_in_ + Y_OFF_ENC + VP8Scan[it->i4_]; |
1241 | uint8_t* const dst = it->yuv_out_ + Y_OFF_ENC + VP8Scan[it->i4_]; |
1242 | VP8MakeIntra4Preds(it); |
1243 | nz |= ReconstructIntra4(it, rd->y_ac_levels[it->i4_], |
1244 | src, dst, mode) << it->i4_; |
1245 | } while (VP8IteratorRotateI4(it, it->yuv_out_ + Y_OFF_ENC)); |
1246 | } |
1247 | |
1248 | nz |= ReconstructUV(it, rd, it->yuv_out_ + U_OFF_ENC, it->mb_->uv_mode_); |
1249 | rd->nz = nz; |
1250 | } |
1251 | |
1252 | // Refine intra16/intra4 sub-modes based on distortion only (not rate). |
1253 | static void RefineUsingDistortion(VP8EncIterator* WEBP_RESTRICT const it, |
1254 | int try_both_modes, int refine_uv_mode, |
1255 | VP8ModeScore* WEBP_RESTRICT const rd) { |
1256 | score_t best_score = MAX_COST; |
1257 | int nz = 0; |
1258 | int mode; |
1259 | int is_i16 = try_both_modes || (it->mb_->type_ == 1); |
1260 | |
1261 | const VP8SegmentInfo* const dqm = &it->enc_->dqm_[it->mb_->segment_]; |
1262 | // Some empiric constants, of approximate order of magnitude. |
1263 | const int lambda_d_i16 = 106; |
1264 | const int lambda_d_i4 = 11; |
1265 | const int lambda_d_uv = 120; |
1266 | score_t score_i4 = dqm->i4_penalty_; |
1267 | score_t i4_bit_sum = 0; |
1268 | const score_t bit_limit = try_both_modes ? it->enc_->mb_header_limit_ |
1269 | : MAX_COST; // no early-out allowed |
1270 | |
1271 | if (is_i16) { // First, evaluate Intra16 distortion |
1272 | int best_mode = -1; |
1273 | const uint8_t* const src = it->yuv_in_ + Y_OFF_ENC; |
1274 | for (mode = 0; mode < NUM_PRED_MODES; ++mode) { |
1275 | const uint8_t* const ref = it->yuv_p_ + VP8I16ModeOffsets[mode]; |
1276 | const score_t score = (score_t)VP8SSE16x16(src, ref) * RD_DISTO_MULT |
1277 | + VP8FixedCostsI16[mode] * lambda_d_i16; |
1278 | if (mode > 0 && VP8FixedCostsI16[mode] > bit_limit) { |
1279 | continue; |
1280 | } |
1281 | |
1282 | if (score < best_score) { |
1283 | best_mode = mode; |
1284 | best_score = score; |
1285 | } |
1286 | } |
1287 | if (it->x_ == 0 || it->y_ == 0) { |
1288 | // avoid starting a checkerboard resonance from the border. See bug #432. |
1289 | if (IsFlatSource16(src)) { |
1290 | best_mode = (it->x_ == 0) ? 0 : 2; |
1291 | try_both_modes = 0; // stick to i16 |
1292 | } |
1293 | } |
1294 | VP8SetIntra16Mode(it, best_mode); |
1295 | // we'll reconstruct later, if i16 mode actually gets selected |
1296 | } |
1297 | |
1298 | // Next, evaluate Intra4 |
1299 | if (try_both_modes || !is_i16) { |
1300 | // We don't evaluate the rate here, but just account for it through a |
1301 | // constant penalty (i4 mode usually needs more bits compared to i16). |
1302 | is_i16 = 0; |
1303 | VP8IteratorStartI4(it); |
1304 | do { |
1305 | int best_i4_mode = -1; |
1306 | score_t best_i4_score = MAX_COST; |
1307 | const uint8_t* const src = it->yuv_in_ + Y_OFF_ENC + VP8Scan[it->i4_]; |
1308 | const uint16_t* const mode_costs = GetCostModeI4(it, rd->modes_i4); |
1309 | |
1310 | VP8MakeIntra4Preds(it); |
1311 | for (mode = 0; mode < NUM_BMODES; ++mode) { |
1312 | const uint8_t* const ref = it->yuv_p_ + VP8I4ModeOffsets[mode]; |
1313 | const score_t score = VP8SSE4x4(src, ref) * RD_DISTO_MULT |
1314 | + mode_costs[mode] * lambda_d_i4; |
1315 | if (score < best_i4_score) { |
1316 | best_i4_mode = mode; |
1317 | best_i4_score = score; |
1318 | } |
1319 | } |
1320 | i4_bit_sum += mode_costs[best_i4_mode]; |
1321 | rd->modes_i4[it->i4_] = best_i4_mode; |
1322 | score_i4 += best_i4_score; |
1323 | if (score_i4 >= best_score || i4_bit_sum > bit_limit) { |
1324 | // Intra4 won't be better than Intra16. Bail out and pick Intra16. |
1325 | is_i16 = 1; |
1326 | break; |
1327 | } else { // reconstruct partial block inside yuv_out2_ buffer |
1328 | uint8_t* const tmp_dst = it->yuv_out2_ + Y_OFF_ENC + VP8Scan[it->i4_]; |
1329 | nz |= ReconstructIntra4(it, rd->y_ac_levels[it->i4_], |
1330 | src, tmp_dst, best_i4_mode) << it->i4_; |
1331 | } |
1332 | } while (VP8IteratorRotateI4(it, it->yuv_out2_ + Y_OFF_ENC)); |
1333 | } |
1334 | |
1335 | // Final reconstruction, depending on which mode is selected. |
1336 | if (!is_i16) { |
1337 | VP8SetIntra4Mode(it, rd->modes_i4); |
1338 | SwapOut(it); |
1339 | best_score = score_i4; |
1340 | } else { |
1341 | nz = ReconstructIntra16(it, rd, it->yuv_out_ + Y_OFF_ENC, it->preds_[0]); |
1342 | } |
1343 | |
1344 | // ... and UV! |
1345 | if (refine_uv_mode) { |
1346 | int best_mode = -1; |
1347 | score_t best_uv_score = MAX_COST; |
1348 | const uint8_t* const src = it->yuv_in_ + U_OFF_ENC; |
1349 | for (mode = 0; mode < NUM_PRED_MODES; ++mode) { |
1350 | const uint8_t* const ref = it->yuv_p_ + VP8UVModeOffsets[mode]; |
1351 | const score_t score = VP8SSE16x8(src, ref) * RD_DISTO_MULT |
1352 | + VP8FixedCostsUV[mode] * lambda_d_uv; |
1353 | if (score < best_uv_score) { |
1354 | best_mode = mode; |
1355 | best_uv_score = score; |
1356 | } |
1357 | } |
1358 | VP8SetIntraUVMode(it, best_mode); |
1359 | } |
1360 | nz |= ReconstructUV(it, rd, it->yuv_out_ + U_OFF_ENC, it->mb_->uv_mode_); |
1361 | |
1362 | rd->nz = nz; |
1363 | rd->score = best_score; |
1364 | } |
1365 | |
1366 | //------------------------------------------------------------------------------ |
1367 | // Entry point |
1368 | |
1369 | int VP8Decimate(VP8EncIterator* WEBP_RESTRICT const it, |
1370 | VP8ModeScore* WEBP_RESTRICT const rd, |
1371 | VP8RDLevel rd_opt) { |
1372 | int is_skipped; |
1373 | const int method = it->enc_->method_; |
1374 | |
1375 | InitScore(rd); |
1376 | |
1377 | // We can perform predictions for Luma16x16 and Chroma8x8 already. |
1378 | // Luma4x4 predictions needs to be done as-we-go. |
1379 | VP8MakeLuma16Preds(it); |
1380 | VP8MakeChroma8Preds(it); |
1381 | |
1382 | if (rd_opt > RD_OPT_NONE) { |
1383 | it->do_trellis_ = (rd_opt >= RD_OPT_TRELLIS_ALL); |
1384 | PickBestIntra16(it, rd); |
1385 | if (method >= 2) { |
1386 | PickBestIntra4(it, rd); |
1387 | } |
1388 | PickBestUV(it, rd); |
1389 | if (rd_opt == RD_OPT_TRELLIS) { // finish off with trellis-optim now |
1390 | it->do_trellis_ = 1; |
1391 | SimpleQuantize(it, rd); |
1392 | } |
1393 | } else { |
1394 | // At this point we have heuristically decided intra16 / intra4. |
1395 | // For method >= 2, pick the best intra4/intra16 based on SSE (~tad slower). |
1396 | // For method <= 1, we don't re-examine the decision but just go ahead with |
1397 | // quantization/reconstruction. |
1398 | RefineUsingDistortion(it, (method >= 2), (method >= 1), rd); |
1399 | } |
1400 | is_skipped = (rd->nz == 0); |
1401 | VP8SetSkip(it, is_skipped); |
1402 | return is_skipped; |
1403 | } |
1404 | |