// Copyright 2011 Google Inc. All Rights Reserved. // // This code is licensed under the same terms as WebM: // Software License Agreement: http://www.webmproject.org/license/software/ // Additional IP Rights Grant: http://www.webmproject.org/license/additional/ // ----------------------------------------------------------------------------- // // Quantization // // Author: Skal (pascal.massimino@gmail.com) #include #include #include "./vp8enci.h" #include "./cost.h" #define DO_TRELLIS_I4 1 #define DO_TRELLIS_I16 1 // not a huge gain, but ok at low bitrate. #define DO_TRELLIS_UV 0 // disable trellis for UV. Risky. Not worth. #define USE_TDISTO 1 #define MID_ALPHA 64 // neutral value for susceptibility #define MIN_ALPHA 30 // lowest usable value for susceptibility #define MAX_ALPHA 100 // higher meaninful value for susceptibility #define SNS_TO_DQ 0.9 // Scaling constant between the sns value and the QP // power-law modulation. Must be strictly less than 1. #define MULT_8B(a, b) (((a) * (b) + 128) >> 8) #if defined(__cplusplus) || defined(c_plusplus) extern "C" { #endif //------------------------------------------------------------------------------ static WEBP_INLINE int clip(int v, int m, int M) { return v < m ? m : v > M ? M : v; } static const uint8_t kZigzag[16] = { 0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15 }; static const uint8_t kDcTable[128] = { 4, 5, 6, 7, 8, 9, 10, 10, 11, 12, 13, 14, 15, 16, 17, 17, 18, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 25, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 91, 93, 95, 96, 98, 100, 101, 102, 104, 106, 108, 110, 112, 114, 116, 118, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 143, 145, 148, 151, 154, 157 }; static const uint16_t kAcTable[128] = { 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 119, 122, 125, 128, 131, 134, 137, 140, 143, 146, 149, 152, 155, 158, 161, 164, 167, 170, 173, 177, 181, 185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229, 234, 239, 245, 249, 254, 259, 264, 269, 274, 279, 284 }; static const uint16_t kAcTable2[128] = { 8, 8, 9, 10, 12, 13, 15, 17, 18, 20, 21, 23, 24, 26, 27, 29, 31, 32, 34, 35, 37, 38, 40, 41, 43, 44, 46, 48, 49, 51, 52, 54, 55, 57, 58, 60, 62, 63, 65, 66, 68, 69, 71, 72, 74, 75, 77, 79, 80, 82, 83, 85, 86, 88, 89, 93, 96, 99, 102, 105, 108, 111, 114, 117, 120, 124, 127, 130, 133, 136, 139, 142, 145, 148, 151, 155, 158, 161, 164, 167, 170, 173, 176, 179, 184, 189, 193, 198, 203, 207, 212, 217, 221, 226, 230, 235, 240, 244, 249, 254, 258, 263, 268, 274, 280, 286, 292, 299, 305, 311, 317, 323, 330, 336, 342, 348, 354, 362, 370, 379, 385, 393, 401, 409, 416, 424, 432, 440 }; static const uint16_t kCoeffThresh[16] = { 0, 10, 20, 30, 10, 20, 30, 30, 20, 30, 30, 30, 30, 30, 30, 30 }; // TODO(skal): tune more. Coeff thresholding? static const uint8_t kBiasMatrices[3][16] = { // [3] = [luma-ac,luma-dc,chroma] { 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96 }, { 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96 }, { 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96, 96 } }; // Sharpening by (slightly) raising the hi-frequency coeffs (only for trellis). // Hack-ish but helpful for mid-bitrate range. Use with care. static const uint8_t kFreqSharpening[16] = { 0, 30, 60, 90, 30, 60, 90, 90, 60, 90, 90, 90, 90, 90, 90, 90 }; //------------------------------------------------------------------------------ // Initialize quantization parameters in VP8Matrix // Returns the average quantizer static int ExpandMatrix(VP8Matrix* const m, int type) { int i; int sum = 0; for (i = 2; i < 16; ++i) { m->q_[i] = m->q_[1]; } for (i = 0; i < 16; ++i) { const int j = kZigzag[i]; const int bias = kBiasMatrices[type][j]; m->iq_[j] = (1 << QFIX) / m->q_[j]; m->bias_[j] = BIAS(bias); // TODO(skal): tune kCoeffThresh[] m->zthresh_[j] = ((256 /*+ kCoeffThresh[j]*/ - bias) * m->q_[j] + 127) >> 8; m->sharpen_[j] = (kFreqSharpening[j] * m->q_[j]) >> 11; sum += m->q_[j]; } return (sum + 8) >> 4; } static void SetupMatrices(VP8Encoder* enc) { int i; const int tlambda_scale = (enc->method_ >= 4) ? enc->config_->sns_strength : 0; const int num_segments = enc->segment_hdr_.num_segments_; for (i = 0; i < num_segments; ++i) { VP8SegmentInfo* const m = &enc->dqm_[i]; const int q = m->quant_; int q4, q16, quv; m->y1_.q_[0] = kDcTable[clip(q + enc->dq_y1_dc_, 0, 127)]; m->y1_.q_[1] = kAcTable[clip(q, 0, 127)]; m->y2_.q_[0] = kDcTable[ clip(q + enc->dq_y2_dc_, 0, 127)] * 2; m->y2_.q_[1] = kAcTable2[clip(q + enc->dq_y2_ac_, 0, 127)]; m->uv_.q_[0] = kDcTable[clip(q + enc->dq_uv_dc_, 0, 117)]; m->uv_.q_[1] = kAcTable[clip(q + enc->dq_uv_ac_, 0, 127)]; q4 = ExpandMatrix(&m->y1_, 0); q16 = ExpandMatrix(&m->y2_, 1); quv = ExpandMatrix(&m->uv_, 2); // TODO: Switch to kLambda*[] tables? { m->lambda_i4_ = (3 * q4 * q4) >> 7; m->lambda_i16_ = (3 * q16 * q16); m->lambda_uv_ = (3 * quv * quv) >> 6; m->lambda_mode_ = (1 * q4 * q4) >> 7; m->lambda_trellis_i4_ = (7 * q4 * q4) >> 3; m->lambda_trellis_i16_ = (q16 * q16) >> 2; m->lambda_trellis_uv_ = (quv *quv) << 1; m->tlambda_ = (tlambda_scale * q4) >> 5; } } } //------------------------------------------------------------------------------ // Initialize filtering parameters // Very small filter-strength values have close to no visual effect. So we can // save a little decoding-CPU by turning filtering off for these. #define FSTRENGTH_CUTOFF 3 static void SetupFilterStrength(VP8Encoder* const enc) { int i; const int level0 = enc->config_->filter_strength; for (i = 0; i < NUM_MB_SEGMENTS; ++i) { // Segments with lower quantizer will be less filtered. TODO: tune (wrt SNS) const int level = level0 * 256 * enc->dqm_[i].quant_ / 128; const int f = level / (256 + enc->dqm_[i].beta_); enc->dqm_[i].fstrength_ = (f < FSTRENGTH_CUTOFF) ? 0 : (f > 63) ? 63 : f; } // We record the initial strength (mainly for the case of 1-segment only). enc->filter_hdr_.level_ = enc->dqm_[0].fstrength_; enc->filter_hdr_.simple_ = (enc->config_->filter_type == 0); enc->filter_hdr_.sharpness_ = enc->config_->filter_sharpness; } //------------------------------------------------------------------------------ // Note: if you change the values below, remember that the max range // allowed by the syntax for DQ_UV is [-16,16]. #define MAX_DQ_UV (6) #define MIN_DQ_UV (-4) // We want to emulate jpeg-like behaviour where the expected "good" quality // is around q=75. Internally, our "good" middle is around c=50. So we // map accordingly using linear piece-wise function static double QualityToCompression(double q) { const double c = q / 100.; return (c < 0.75) ? c * (2. / 3.) : 2. * c - 1.; } void VP8SetSegmentParams(VP8Encoder* const enc, float quality) { int i; int dq_uv_ac, dq_uv_dc; const int num_segments = enc->config_->segments; const double amp = SNS_TO_DQ * enc->config_->sns_strength / 100. / 128.; const double c_base = QualityToCompression(quality); for (i = 0; i < num_segments; ++i) { // The file size roughly scales as pow(quantizer, 3.). Actually, the // exponent is somewhere between 2.8 and 3.2, but we're mostly interested // in the mid-quant range. So we scale the compressibility inversely to // this power-law: quant ~= compression ^ 1/3. This law holds well for // low quant. Finer modelling for high-quant would make use of kAcTable[] // more explicitely. // Additionally, we modulate the base exponent 1/3 to accommodate for the // quantization susceptibility and allow denser segments to be quantized // more. const double expn = (1. - amp * enc->dqm_[i].alpha_) / 3.; const double c = pow(c_base, expn); const int q = (int)(127. * (1. - c)); assert(expn > 0.); enc->dqm_[i].quant_ = clip(q, 0, 127); } // purely indicative in the bitstream (except for the 1-segment case) enc->base_quant_ = enc->dqm_[0].quant_; // fill-in values for the unused segments (required by the syntax) for (i = num_segments; i < NUM_MB_SEGMENTS; ++i) { enc->dqm_[i].quant_ = enc->base_quant_; } // uv_alpha_ is normally spread around ~60. The useful range is // typically ~30 (quite bad) to ~100 (ok to decimate UV more). // We map it to the safe maximal range of MAX/MIN_DQ_UV for dq_uv. dq_uv_ac = (enc->uv_alpha_ - MID_ALPHA) * (MAX_DQ_UV - MIN_DQ_UV) / (MAX_ALPHA - MIN_ALPHA); // we rescale by the user-defined strength of adaptation dq_uv_ac = dq_uv_ac * enc->config_->sns_strength / 100; // and make it safe. dq_uv_ac = clip(dq_uv_ac, MIN_DQ_UV, MAX_DQ_UV); // We also boost the dc-uv-quant a little, based on sns-strength, since // U/V channels are quite more reactive to high quants (flat DC-blocks // tend to appear, and are displeasant). dq_uv_dc = -4 * enc->config_->sns_strength / 100; dq_uv_dc = clip(dq_uv_dc, -15, 15); // 4bit-signed max allowed enc->dq_y1_dc_ = 0; // TODO(skal): dq-lum enc->dq_y2_dc_ = 0; enc->dq_y2_ac_ = 0; enc->dq_uv_dc_ = dq_uv_dc; enc->dq_uv_ac_ = dq_uv_ac; SetupMatrices(enc); SetupFilterStrength(enc); // initialize segments' filtering, eventually } //------------------------------------------------------------------------------ // Form the predictions in cache // Must be ordered using {DC_PRED, TM_PRED, V_PRED, H_PRED} as index const int VP8I16ModeOffsets[4] = { I16DC16, I16TM16, I16VE16, I16HE16 }; const int VP8UVModeOffsets[4] = { C8DC8, C8TM8, C8VE8, C8HE8 }; // Must be indexed using {B_DC_PRED -> B_HU_PRED} as index const int VP8I4ModeOffsets[NUM_BMODES] = { I4DC4, I4TM4, I4VE4, I4HE4, I4RD4, I4VR4, I4LD4, I4VL4, I4HD4, I4HU4 }; void VP8MakeLuma16Preds(const VP8EncIterator* const it) { const VP8Encoder* const enc = it->enc_; const uint8_t* const left = it->x_ ? enc->y_left_ : NULL; const uint8_t* const top = it->y_ ? enc->y_top_ + it->x_ * 16 : NULL; VP8EncPredLuma16(it->yuv_p_, left, top); } void VP8MakeChroma8Preds(const VP8EncIterator* const it) { const VP8Encoder* const enc = it->enc_; const uint8_t* const left = it->x_ ? enc->u_left_ : NULL; const uint8_t* const top = it->y_ ? enc->uv_top_ + it->x_ * 16 : NULL; VP8EncPredChroma8(it->yuv_p_, left, top); } void VP8MakeIntra4Preds(const VP8EncIterator* const it) { VP8EncPredLuma4(it->yuv_p_, it->i4_top_); } //------------------------------------------------------------------------------ // Quantize // Layout: // +----+ // |YYYY| 0 // |YYYY| 4 // |YYYY| 8 // |YYYY| 12 // +----+ // |UUVV| 16 // |UUVV| 20 // +----+ const int VP8Scan[16 + 4 + 4] = { // Luma 0 + 0 * BPS, 4 + 0 * BPS, 8 + 0 * BPS, 12 + 0 * BPS, 0 + 4 * BPS, 4 + 4 * BPS, 8 + 4 * BPS, 12 + 4 * BPS, 0 + 8 * BPS, 4 + 8 * BPS, 8 + 8 * BPS, 12 + 8 * BPS, 0 + 12 * BPS, 4 + 12 * BPS, 8 + 12 * BPS, 12 + 12 * BPS, 0 + 0 * BPS, 4 + 0 * BPS, 0 + 4 * BPS, 4 + 4 * BPS, // U 8 + 0 * BPS, 12 + 0 * BPS, 8 + 4 * BPS, 12 + 4 * BPS // V }; //------------------------------------------------------------------------------ // Distortion measurement static const uint16_t kWeightY[16] = { 38, 32, 20, 9, 32, 28, 17, 7, 20, 17, 10, 4, 9, 7, 4, 2 }; static const uint16_t kWeightTrellis[16] = { #if USE_TDISTO == 0 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16 #else 30, 27, 19, 11, 27, 24, 17, 10, 19, 17, 12, 8, 11, 10, 8, 6 #endif }; // Init/Copy the common fields in score. static void InitScore(VP8ModeScore* const rd) { rd->D = 0; rd->SD = 0; rd->R = 0; rd->nz = 0; rd->score = MAX_COST; } static void CopyScore(VP8ModeScore* const dst, const VP8ModeScore* const src) { dst->D = src->D; dst->SD = src->SD; dst->R = src->R; dst->nz = src->nz; // note that nz is not accumulated, but just copied. dst->score = src->score; } static void AddScore(VP8ModeScore* const dst, const VP8ModeScore* const src) { dst->D += src->D; dst->SD += src->SD; dst->R += src->R; dst->nz |= src->nz; // here, new nz bits are accumulated. dst->score += src->score; } //------------------------------------------------------------------------------ // Performs trellis-optimized quantization. // Trellis typedef struct { int prev; // best previous int level; // level int sign; // sign of coeff_i score_t cost; // bit cost score_t error; // distortion = sum of (|coeff_i| - level_i * Q_i)^2 int ctx; // context (only depends on 'level'. Could be spared.) } Node; // If a coefficient was quantized to a value Q (using a neutral bias), // we test all alternate possibilities between [Q-MIN_DELTA, Q+MAX_DELTA] // We don't test negative values though. #define MIN_DELTA 0 // how much lower level to try #define MAX_DELTA 1 // how much higher #define NUM_NODES (MIN_DELTA + 1 + MAX_DELTA) #define NODE(n, l) (nodes[(n) + 1][(l) + MIN_DELTA]) static WEBP_INLINE void SetRDScore(int lambda, VP8ModeScore* const rd) { // TODO: incorporate the "* 256" in the tables? rd->score = rd->R * lambda + 256 * (rd->D + rd->SD); } static WEBP_INLINE score_t RDScoreTrellis(int lambda, score_t rate, score_t distortion) { return rate * lambda + 256 * distortion; } static int TrellisQuantizeBlock(const VP8EncIterator* const it, int16_t in[16], int16_t out[16], int ctx0, int coeff_type, const VP8Matrix* const mtx, int lambda) { ProbaArray* const last_costs = it->enc_->proba_.coeffs_[coeff_type]; CostArray* const costs = it->enc_->proba_.level_cost_[coeff_type]; const int first = (coeff_type == 0) ? 1 : 0; Node nodes[17][NUM_NODES]; int best_path[3] = {-1, -1, -1}; // store best-last/best-level/best-previous score_t best_score; int best_node; int last = first - 1; int n, m, p, nz; { score_t cost; score_t max_error; const int thresh = mtx->q_[1] * mtx->q_[1] / 4; const int last_proba = last_costs[VP8EncBands[first]][ctx0][0]; // compute maximal distortion. max_error = 0; for (n = first; n < 16; ++n) { const int j = kZigzag[n]; const int err = in[j] * in[j]; max_error += kWeightTrellis[j] * err; if (err > thresh) last = n; } // we don't need to go inspect up to n = 16 coeffs. We can just go up // to last + 1 (inclusive) without losing much. if (last < 15) ++last; // compute 'skip' score. This is the max score one can do. cost = VP8BitCost(0, last_proba); best_score = RDScoreTrellis(lambda, cost, max_error); // initialize source node. n = first - 1; for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { NODE(n, m).cost = 0; NODE(n, m).error = max_error; NODE(n, m).ctx = ctx0; } } // traverse trellis. for (n = first; n <= last; ++n) { const int j = kZigzag[n]; const int Q = mtx->q_[j]; const int iQ = mtx->iq_[j]; const int B = BIAS(0x00); // neutral bias // note: it's important to take sign of the _original_ coeff, // so we don't have to consider level < 0 afterward. const int sign = (in[j] < 0); int coeff0 = (sign ? -in[j] : in[j]) + mtx->sharpen_[j]; int level0; if (coeff0 > 2047) coeff0 = 2047; level0 = QUANTDIV(coeff0, iQ, B); // test all alternate level values around level0. for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { Node* const cur = &NODE(n, m); int delta_error, new_error; score_t cur_score = MAX_COST; int level = level0 + m; int last_proba; cur->sign = sign; cur->level = level; cur->ctx = (level == 0) ? 0 : (level == 1) ? 1 : 2; if (level >= 2048 || level < 0) { // node is dead? cur->cost = MAX_COST; continue; } last_proba = last_costs[VP8EncBands[n + 1]][cur->ctx][0]; // Compute delta_error = how much coding this level will // subtract as distortion to max_error new_error = coeff0 - level * Q; delta_error = kWeightTrellis[j] * (coeff0 * coeff0 - new_error * new_error); // Inspect all possible non-dead predecessors. Retain only the best one. for (p = -MIN_DELTA; p <= MAX_DELTA; ++p) { const Node* const prev = &NODE(n - 1, p); const int prev_ctx = prev->ctx; const uint16_t* const tcost = costs[VP8EncBands[n]][prev_ctx]; const score_t total_error = prev->error - delta_error; score_t cost, base_cost, score; if (prev->cost >= MAX_COST) { // dead node? continue; } // Base cost of both terminal/non-terminal base_cost = prev->cost + VP8LevelCost(tcost, level); // Examine node assuming it's a non-terminal one. cost = base_cost; if (level && n < 15) { cost += VP8BitCost(1, last_proba); } score = RDScoreTrellis(lambda, cost, total_error); if (score < cur_score) { cur_score = score; cur->cost = cost; cur->error = total_error; cur->prev = p; } // Now, record best terminal node (and thus best entry in the graph). if (level) { cost = base_cost; if (n < 15) cost += VP8BitCost(0, last_proba); score = RDScoreTrellis(lambda, cost, total_error); if (score < best_score) { best_score = score; best_path[0] = n; // best eob position best_path[1] = m; // best level best_path[2] = p; // best predecessor } } } } } // Fresh start memset(in + first, 0, (16 - first) * sizeof(*in)); memset(out + first, 0, (16 - first) * sizeof(*out)); if (best_path[0] == -1) { return 0; // skip! } // Unwind the best path. // Note: best-prev on terminal node is not necessarily equal to the // best_prev for non-terminal. So we patch best_path[2] in. n = best_path[0]; best_node = best_path[1]; NODE(n, best_node).prev = best_path[2]; // force best-prev for terminal nz = 0; for (; n >= first; --n) { const Node* const node = &NODE(n, best_node); const int j = kZigzag[n]; out[n] = node->sign ? -node->level : node->level; nz |= (node->level != 0); in[j] = out[n] * mtx->q_[j]; best_node = node->prev; } return nz; } #undef NODE //------------------------------------------------------------------------------ // Performs: difference, transform, quantize, back-transform, add // all at once. Output is the reconstructed block in *yuv_out, and the // quantized levels in *levels. static int ReconstructIntra16(VP8EncIterator* const it, VP8ModeScore* const rd, uint8_t* const yuv_out, int mode) { const VP8Encoder* const enc = it->enc_; const uint8_t* const ref = it->yuv_p_ + VP8I16ModeOffsets[mode]; const uint8_t* const src = it->yuv_in_ + Y_OFF; const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; int nz = 0; int n; int16_t tmp[16][16], dc_tmp[16]; for (n = 0; n < 16; ++n) { VP8FTransform(src + VP8Scan[n], ref + VP8Scan[n], tmp[n]); } VP8FTransformWHT(tmp[0], dc_tmp); nz |= VP8EncQuantizeBlock(dc_tmp, rd->y_dc_levels, 0, &dqm->y2_) << 24; if (DO_TRELLIS_I16 && it->do_trellis_) { int x, y; VP8IteratorNzToBytes(it); for (y = 0, n = 0; y < 4; ++y) { for (x = 0; x < 4; ++x, ++n) { const int ctx = it->top_nz_[x] + it->left_nz_[y]; const int non_zero = TrellisQuantizeBlock(it, tmp[n], rd->y_ac_levels[n], ctx, 0, &dqm->y1_, dqm->lambda_trellis_i16_); it->top_nz_[x] = it->left_nz_[y] = non_zero; nz |= non_zero << n; } } } else { for (n = 0; n < 16; ++n) { nz |= VP8EncQuantizeBlock(tmp[n], rd->y_ac_levels[n], 1, &dqm->y1_) << n; } } // Transform back VP8ITransformWHT(dc_tmp, tmp[0]); for (n = 0; n < 16; n += 2) { VP8ITransform(ref + VP8Scan[n], tmp[n], yuv_out + VP8Scan[n], 1); } return nz; } static int ReconstructIntra4(VP8EncIterator* const it, int16_t levels[16], const uint8_t* const src, uint8_t* const yuv_out, int mode) { const VP8Encoder* const enc = it->enc_; const uint8_t* const ref = it->yuv_p_ + VP8I4ModeOffsets[mode]; const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; int nz = 0; int16_t tmp[16]; VP8FTransform(src, ref, tmp); if (DO_TRELLIS_I4 && it->do_trellis_) { const int x = it->i4_ & 3, y = it->i4_ >> 2; const int ctx = it->top_nz_[x] + it->left_nz_[y]; nz = TrellisQuantizeBlock(it, tmp, levels, ctx, 3, &dqm->y1_, dqm->lambda_trellis_i4_); } else { nz = VP8EncQuantizeBlock(tmp, levels, 0, &dqm->y1_); } VP8ITransform(ref, tmp, yuv_out, 0); return nz; } static int ReconstructUV(VP8EncIterator* const it, VP8ModeScore* const rd, uint8_t* const yuv_out, int mode) { const VP8Encoder* const enc = it->enc_; const uint8_t* const ref = it->yuv_p_ + VP8UVModeOffsets[mode]; const uint8_t* const src = it->yuv_in_ + U_OFF; const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; int nz = 0; int n; int16_t tmp[8][16]; for (n = 0; n < 8; ++n) { VP8FTransform(src + VP8Scan[16 + n], ref + VP8Scan[16 + n], tmp[n]); } if (DO_TRELLIS_UV && it->do_trellis_) { int ch, x, y; for (ch = 0, n = 0; ch <= 2; ch += 2) { for (y = 0; y < 2; ++y) { for (x = 0; x < 2; ++x, ++n) { const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y]; const int non_zero = TrellisQuantizeBlock(it, tmp[n], rd->uv_levels[n], ctx, 2, &dqm->uv_, dqm->lambda_trellis_uv_); it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] = non_zero; nz |= non_zero << n; } } } } else { for (n = 0; n < 8; ++n) { nz |= VP8EncQuantizeBlock(tmp[n], rd->uv_levels[n], 0, &dqm->uv_) << n; } } for (n = 0; n < 8; n += 2) { VP8ITransform(ref + VP8Scan[16 + n], tmp[n], yuv_out + VP8Scan[16 + n], 1); } return (nz << 16); } //------------------------------------------------------------------------------ // RD-opt decision. Reconstruct each modes, evalue distortion and bit-cost. // Pick the mode is lower RD-cost = Rate + lamba * Distortion. static void SwapPtr(uint8_t** a, uint8_t** b) { uint8_t* const tmp = *a; *a = *b; *b = tmp; } static void SwapOut(VP8EncIterator* const it) { SwapPtr(&it->yuv_out_, &it->yuv_out2_); } static void PickBestIntra16(VP8EncIterator* const it, VP8ModeScore* const rd) { const VP8Encoder* const enc = it->enc_; const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; const int lambda = dqm->lambda_i16_; const int tlambda = dqm->tlambda_; const uint8_t* const src = it->yuv_in_ + Y_OFF; VP8ModeScore rd16; int mode; rd->mode_i16 = -1; for (mode = 0; mode < 4; ++mode) { uint8_t* const tmp_dst = it->yuv_out2_ + Y_OFF; // scratch buffer int nz; // Reconstruct nz = ReconstructIntra16(it, &rd16, tmp_dst, mode); // Measure RD-score rd16.D = VP8SSE16x16(src, tmp_dst); rd16.SD = tlambda ? MULT_8B(tlambda, VP8TDisto16x16(src, tmp_dst, kWeightY)) : 0; rd16.R = VP8GetCostLuma16(it, &rd16); rd16.R += VP8FixedCostsI16[mode]; // Since we always examine Intra16 first, we can overwrite *rd directly. SetRDScore(lambda, &rd16); if (mode == 0 || rd16.score < rd->score) { CopyScore(rd, &rd16); rd->mode_i16 = mode; rd->nz = nz; memcpy(rd->y_ac_levels, rd16.y_ac_levels, sizeof(rd16.y_ac_levels)); memcpy(rd->y_dc_levels, rd16.y_dc_levels, sizeof(rd16.y_dc_levels)); SwapOut(it); } } SetRDScore(dqm->lambda_mode_, rd); // finalize score for mode decision. VP8SetIntra16Mode(it, rd->mode_i16); } //------------------------------------------------------------------------------ // return the cost array corresponding to the surrounding prediction modes. static const uint16_t* GetCostModeI4(VP8EncIterator* const it, const uint8_t modes[16]) { const int preds_w = it->enc_->preds_w_; const int x = (it->i4_ & 3), y = it->i4_ >> 2; const int left = (x == 0) ? it->preds_[y * preds_w - 1] : modes[it->i4_ - 1]; const int top = (y == 0) ? it->preds_[-preds_w + x] : modes[it->i4_ - 4]; return VP8FixedCostsI4[top][left]; } static int PickBestIntra4(VP8EncIterator* const it, VP8ModeScore* const rd) { const VP8Encoder* const enc = it->enc_; const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; const int lambda = dqm->lambda_i4_; const int tlambda = dqm->tlambda_; const uint8_t* const src0 = it->yuv_in_ + Y_OFF; uint8_t* const best_blocks = it->yuv_out2_ + Y_OFF; int total_header_bits = 0; VP8ModeScore rd_best; if (enc->max_i4_header_bits_ == 0) { return 0; } InitScore(&rd_best); rd_best.score = 211; // '211' is the value of VP8BitCost(0, 145) VP8IteratorStartI4(it); do { VP8ModeScore rd_i4; int mode; int best_mode = -1; const uint8_t* const src = src0 + VP8Scan[it->i4_]; const uint16_t* const mode_costs = GetCostModeI4(it, rd->modes_i4); uint8_t* best_block = best_blocks + VP8Scan[it->i4_]; uint8_t* tmp_dst = it->yuv_p_ + I4TMP; // scratch buffer. InitScore(&rd_i4); VP8MakeIntra4Preds(it); for (mode = 0; mode < NUM_BMODES; ++mode) { VP8ModeScore rd_tmp; int16_t tmp_levels[16]; // Reconstruct rd_tmp.nz = ReconstructIntra4(it, tmp_levels, src, tmp_dst, mode) << it->i4_; // Compute RD-score rd_tmp.D = VP8SSE4x4(src, tmp_dst); rd_tmp.SD = tlambda ? MULT_8B(tlambda, VP8TDisto4x4(src, tmp_dst, kWeightY)) : 0; rd_tmp.R = VP8GetCostLuma4(it, tmp_levels); rd_tmp.R += mode_costs[mode]; SetRDScore(lambda, &rd_tmp); if (best_mode < 0 || rd_tmp.score < rd_i4.score) { CopyScore(&rd_i4, &rd_tmp); best_mode = mode; SwapPtr(&tmp_dst, &best_block); memcpy(rd_best.y_ac_levels[it->i4_], tmp_levels, sizeof(tmp_levels)); } } SetRDScore(dqm->lambda_mode_, &rd_i4); AddScore(&rd_best, &rd_i4); total_header_bits += mode_costs[best_mode]; if (rd_best.score >= rd->score || total_header_bits > enc->max_i4_header_bits_) { return 0; } // Copy selected samples if not in the right place already. if (best_block != best_blocks + VP8Scan[it->i4_]) VP8Copy4x4(best_block, best_blocks + VP8Scan[it->i4_]); rd->modes_i4[it->i4_] = best_mode; it->top_nz_[it->i4_ & 3] = it->left_nz_[it->i4_ >> 2] = (rd_i4.nz ? 1 : 0); } while (VP8IteratorRotateI4(it, best_blocks)); // finalize state CopyScore(rd, &rd_best); VP8SetIntra4Mode(it, rd->modes_i4); SwapOut(it); memcpy(rd->y_ac_levels, rd_best.y_ac_levels, sizeof(rd->y_ac_levels)); return 1; // select intra4x4 over intra16x16 } //------------------------------------------------------------------------------ static void PickBestUV(VP8EncIterator* const it, VP8ModeScore* const rd) { const VP8Encoder* const enc = it->enc_; const VP8SegmentInfo* const dqm = &enc->dqm_[it->mb_->segment_]; const int lambda = dqm->lambda_uv_; const uint8_t* const src = it->yuv_in_ + U_OFF; uint8_t* const tmp_dst = it->yuv_out2_ + U_OFF; // scratch buffer uint8_t* const dst0 = it->yuv_out_ + U_OFF; VP8ModeScore rd_best; int mode; rd->mode_uv = -1; InitScore(&rd_best); for (mode = 0; mode < 4; ++mode) { VP8ModeScore rd_uv; // Reconstruct rd_uv.nz = ReconstructUV(it, &rd_uv, tmp_dst, mode); // Compute RD-score rd_uv.D = VP8SSE16x8(src, tmp_dst); rd_uv.SD = 0; // TODO: should we call TDisto? it tends to flatten areas. rd_uv.R = VP8GetCostUV(it, &rd_uv); rd_uv.R += VP8FixedCostsUV[mode]; SetRDScore(lambda, &rd_uv); if (mode == 0 || rd_uv.score < rd_best.score) { CopyScore(&rd_best, &rd_uv); rd->mode_uv = mode; memcpy(rd->uv_levels, rd_uv.uv_levels, sizeof(rd->uv_levels)); memcpy(dst0, tmp_dst, UV_SIZE); // TODO: SwapUVOut() ? } } VP8SetIntraUVMode(it, rd->mode_uv); AddScore(rd, &rd_best); } //------------------------------------------------------------------------------ // Final reconstruction and quantization. static void SimpleQuantize(VP8EncIterator* const it, VP8ModeScore* const rd) { const VP8Encoder* const enc = it->enc_; const int i16 = (it->mb_->type_ == 1); int nz = 0; if (i16) { nz = ReconstructIntra16(it, rd, it->yuv_out_ + Y_OFF, it->preds_[0]); } else { VP8IteratorStartI4(it); do { const int mode = it->preds_[(it->i4_ & 3) + (it->i4_ >> 2) * enc->preds_w_]; const uint8_t* const src = it->yuv_in_ + Y_OFF + VP8Scan[it->i4_]; uint8_t* const dst = it->yuv_out_ + Y_OFF + VP8Scan[it->i4_]; VP8MakeIntra4Preds(it); nz |= ReconstructIntra4(it, rd->y_ac_levels[it->i4_], src, dst, mode) << it->i4_; } while (VP8IteratorRotateI4(it, it->yuv_out_ + Y_OFF)); } nz |= ReconstructUV(it, rd, it->yuv_out_ + U_OFF, it->mb_->uv_mode_); rd->nz = nz; } //------------------------------------------------------------------------------ // Entry point int VP8Decimate(VP8EncIterator* const it, VP8ModeScore* const rd, int rd_opt) { int is_skipped; InitScore(rd); // We can perform predictions for Luma16x16 and Chroma8x8 already. // Luma4x4 predictions needs to be done as-we-go. VP8MakeLuma16Preds(it); VP8MakeChroma8Preds(it); // for rd_opt = 2, we perform trellis-quant on the final decision only. // for rd_opt > 2, we use it for every scoring (=much slower). if (rd_opt > 0) { it->do_trellis_ = (rd_opt > 2); PickBestIntra16(it, rd); if (it->enc_->method_ >= 2) { PickBestIntra4(it, rd); } PickBestUV(it, rd); if (rd_opt == 2) { it->do_trellis_ = 1; SimpleQuantize(it, rd); } } else { // TODO: for method_ == 2, pick the best intra4/intra16 based on SSE it->do_trellis_ = (it->enc_->method_ == 2); SimpleQuantize(it, rd); } is_skipped = (rd->nz == 0); VP8SetSkip(it, is_skipped); return is_skipped; } #if defined(__cplusplus) || defined(c_plusplus) } // extern "C" #endif