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Diffstat (limited to 'media/libwebp/src/enc/quant_enc.c')
| -rw-r--r-- | media/libwebp/src/enc/quant_enc.c | 1398 |
1 files changed, 1398 insertions, 0 deletions
diff --git a/media/libwebp/src/enc/quant_enc.c b/media/libwebp/src/enc/quant_enc.c new file mode 100644 index 0000000000..6d8202d277 --- /dev/null +++ b/media/libwebp/src/enc/quant_enc.c @@ -0,0 +1,1398 @@ +// Copyright 2011 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// Quantization +// +// Author: Skal (pascal.massimino@gmail.com) + +#include <assert.h> +#include <math.h> +#include <stdlib.h> // for abs() + +#include "src/dsp/quant.h" +#include "src/enc/vp8i_enc.h" +#include "src/enc/cost_enc.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 meaningful 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. + +// number of non-zero coeffs below which we consider the block very flat +// (and apply a penalty to complex predictions) +#define FLATNESS_LIMIT_I16 0 // I16 mode (special case) +#define FLATNESS_LIMIT_I4 3 // I4 mode +#define FLATNESS_LIMIT_UV 2 // UV mode +#define FLATNESS_PENALTY 140 // roughly ~1bit per block + +#define MULT_8B(a, b) (((a) * (b) + 128) >> 8) + +#define RD_DISTO_MULT 256 // distortion multiplier (equivalent of lambda) + +// #define DEBUG_BLOCK + +//------------------------------------------------------------------------------ + +#if defined(DEBUG_BLOCK) + +#include <stdio.h> +#include <stdlib.h> + +static void PrintBlockInfo(const VP8EncIterator* const it, + const VP8ModeScore* const rd) { + int i, j; + const int is_i16 = (it->mb_->type_ == 1); + const uint8_t* const y_in = it->yuv_in_ + Y_OFF_ENC; + const uint8_t* const y_out = it->yuv_out_ + Y_OFF_ENC; + const uint8_t* const uv_in = it->yuv_in_ + U_OFF_ENC; + const uint8_t* const uv_out = it->yuv_out_ + U_OFF_ENC; + printf("SOURCE / OUTPUT / ABS DELTA\n"); + for (j = 0; j < 16; ++j) { + for (i = 0; i < 16; ++i) printf("%3d ", y_in[i + j * BPS]); + printf(" "); + for (i = 0; i < 16; ++i) printf("%3d ", y_out[i + j * BPS]); + printf(" "); + for (i = 0; i < 16; ++i) { + printf("%1d ", abs(y_in[i + j * BPS] - y_out[i + j * BPS])); + } + printf("\n"); + } + printf("\n"); // newline before the U/V block + for (j = 0; j < 8; ++j) { + for (i = 0; i < 8; ++i) printf("%3d ", uv_in[i + j * BPS]); + printf(" "); + for (i = 8; i < 16; ++i) printf("%3d ", uv_in[i + j * BPS]); + printf(" "); + for (i = 0; i < 8; ++i) printf("%3d ", uv_out[i + j * BPS]); + printf(" "); + for (i = 8; i < 16; ++i) printf("%3d ", uv_out[i + j * BPS]); + printf(" "); + for (i = 0; i < 8; ++i) { + printf("%1d ", abs(uv_out[i + j * BPS] - uv_in[i + j * BPS])); + } + printf(" "); + for (i = 8; i < 16; ++i) { + printf("%1d ", abs(uv_out[i + j * BPS] - uv_in[i + j * BPS])); + } + printf("\n"); + } + printf("\nD:%d SD:%d R:%d H:%d nz:0x%x score:%d\n", + (int)rd->D, (int)rd->SD, (int)rd->R, (int)rd->H, (int)rd->nz, + (int)rd->score); + if (is_i16) { + printf("Mode: %d\n", rd->mode_i16); + printf("y_dc_levels:"); + for (i = 0; i < 16; ++i) printf("%3d ", rd->y_dc_levels[i]); + printf("\n"); + } else { + printf("Modes[16]: "); + for (i = 0; i < 16; ++i) printf("%d ", rd->modes_i4[i]); + printf("\n"); + } + printf("y_ac_levels:\n"); + for (j = 0; j < 16; ++j) { + for (i = is_i16 ? 1 : 0; i < 16; ++i) { + printf("%4d ", rd->y_ac_levels[j][i]); + } + printf("\n"); + } + printf("\n"); + printf("uv_levels (mode=%d):\n", rd->mode_uv); + for (j = 0; j < 8; ++j) { + for (i = 0; i < 16; ++i) { + printf("%4d ", rd->uv_levels[j][i]); + } + printf("\n"); + } +} + +#endif // DEBUG_BLOCK + +//------------------------------------------------------------------------------ + +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 uint8_t kBiasMatrices[3][2] = { // [luma-ac,luma-dc,chroma][dc,ac] + { 96, 110 }, { 96, 108 }, { 110, 115 } +}; + +// Sharpening by (slightly) raising the hi-frequency coeffs. +// Hack-ish but helpful for mid-bitrate range. Use with care. +#define SHARPEN_BITS 11 // number of descaling bits for sharpening bias +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, sum; + for (i = 0; i < 2; ++i) { + const int is_ac_coeff = (i > 0); + const int bias = kBiasMatrices[type][is_ac_coeff]; + m->iq_[i] = (1 << QFIX) / m->q_[i]; + m->bias_[i] = BIAS(bias); + // zthresh_ is the exact value such that QUANTDIV(coeff, iQ, B) is: + // * zero if coeff <= zthresh + // * non-zero if coeff > zthresh + m->zthresh_[i] = ((1 << QFIX) - 1 - m->bias_[i]) / m->iq_[i]; + } + for (i = 2; i < 16; ++i) { + m->q_[i] = m->q_[1]; + m->iq_[i] = m->iq_[1]; + m->bias_[i] = m->bias_[1]; + m->zthresh_[i] = m->zthresh_[1]; + } + for (sum = 0, i = 0; i < 16; ++i) { + if (type == 0) { // we only use sharpening for AC luma coeffs + m->sharpen_[i] = (kFreqSharpening[i] * m->q_[i]) >> SHARPEN_BITS; + } else { + m->sharpen_[i] = 0; + } + sum += m->q_[i]; + } + return (sum + 8) >> 4; +} + +static void CheckLambdaValue(int* const v) { if (*v < 1) *v = 1; } + +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 q_i4, q_i16, q_uv; + 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)]; + + q_i4 = ExpandMatrix(&m->y1_, 0); + q_i16 = ExpandMatrix(&m->y2_, 1); + q_uv = ExpandMatrix(&m->uv_, 2); + + m->lambda_i4_ = (3 * q_i4 * q_i4) >> 7; + m->lambda_i16_ = (3 * q_i16 * q_i16); + m->lambda_uv_ = (3 * q_uv * q_uv) >> 6; + m->lambda_mode_ = (1 * q_i4 * q_i4) >> 7; + m->lambda_trellis_i4_ = (7 * q_i4 * q_i4) >> 3; + m->lambda_trellis_i16_ = (q_i16 * q_i16) >> 2; + m->lambda_trellis_uv_ = (q_uv * q_uv) << 1; + m->tlambda_ = (tlambda_scale * q_i4) >> 5; + + // none of these constants should be < 1 + CheckLambdaValue(&m->lambda_i4_); + CheckLambdaValue(&m->lambda_i16_); + CheckLambdaValue(&m->lambda_uv_); + CheckLambdaValue(&m->lambda_mode_); + CheckLambdaValue(&m->lambda_trellis_i4_); + CheckLambdaValue(&m->lambda_trellis_i16_); + CheckLambdaValue(&m->lambda_trellis_uv_); + CheckLambdaValue(&m->tlambda_); + + m->min_disto_ = 20 * m->y1_.q_[0]; // quantization-aware min disto + m->max_edge_ = 0; + + m->i4_penalty_ = 1000 * q_i4 * q_i4; + } +} + +//------------------------------------------------------------------------------ +// 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 2 + +static void SetupFilterStrength(VP8Encoder* const enc) { + int i; + // level0 is in [0..500]. Using '-f 50' as filter_strength is mid-filtering. + const int level0 = 5 * enc->config_->filter_strength; + for (i = 0; i < NUM_MB_SEGMENTS; ++i) { + VP8SegmentInfo* const m = &enc->dqm_[i]; + // We focus on the quantization of AC coeffs. + const int qstep = kAcTable[clip(m->quant_, 0, 127)] >> 2; + const int base_strength = + VP8FilterStrengthFromDelta(enc->filter_hdr_.sharpness_, qstep); + // Segments with lower complexity ('beta') will be less filtered. + const int f = base_strength * level0 / (256 + m->beta_); + m->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 c) { + const double linear_c = (c < 0.75) ? c * (2. / 3.) : 2. * c - 1.; + // 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 modeling for high-quant would make use of kAcTable[] + // more explicitly. + const double v = pow(linear_c, 1 / 3.); + return v; +} + +static double QualityToJPEGCompression(double c, double alpha) { + // We map the complexity 'alpha' and quality setting 'c' to a compression + // exponent empirically matched to the compression curve of libjpeg6b. + // On average, the WebP output size will be roughly similar to that of a + // JPEG file compressed with same quality factor. + const double amin = 0.30; + const double amax = 0.85; + const double exp_min = 0.4; + const double exp_max = 0.9; + const double slope = (exp_min - exp_max) / (amax - amin); + // Linearly interpolate 'expn' from exp_min to exp_max + // in the [amin, amax] range. + const double expn = (alpha > amax) ? exp_min + : (alpha < amin) ? exp_max + : exp_max + slope * (alpha - amin); + const double v = pow(c, expn); + return v; +} + +static int SegmentsAreEquivalent(const VP8SegmentInfo* const S1, + const VP8SegmentInfo* const S2) { + return (S1->quant_ == S2->quant_) && (S1->fstrength_ == S2->fstrength_); +} + +static void SimplifySegments(VP8Encoder* const enc) { + int map[NUM_MB_SEGMENTS] = { 0, 1, 2, 3 }; + // 'num_segments_' is previously validated and <= NUM_MB_SEGMENTS, but an + // explicit check is needed to avoid a spurious warning about 'i' exceeding + // array bounds of 'dqm_' with some compilers (noticed with gcc-4.9). + const int num_segments = (enc->segment_hdr_.num_segments_ < NUM_MB_SEGMENTS) + ? enc->segment_hdr_.num_segments_ + : NUM_MB_SEGMENTS; + int num_final_segments = 1; + int s1, s2; + for (s1 = 1; s1 < num_segments; ++s1) { // find similar segments + const VP8SegmentInfo* const S1 = &enc->dqm_[s1]; + int found = 0; + // check if we already have similar segment + for (s2 = 0; s2 < num_final_segments; ++s2) { + const VP8SegmentInfo* const S2 = &enc->dqm_[s2]; + if (SegmentsAreEquivalent(S1, S2)) { + found = 1; + break; + } + } + map[s1] = s2; + if (!found) { + if (num_final_segments != s1) { + enc->dqm_[num_final_segments] = enc->dqm_[s1]; + } + ++num_final_segments; + } + } + if (num_final_segments < num_segments) { // Remap + int i = enc->mb_w_ * enc->mb_h_; + while (i-- > 0) enc->mb_info_[i].segment_ = map[enc->mb_info_[i].segment_]; + enc->segment_hdr_.num_segments_ = num_final_segments; + // Replicate the trailing segment infos (it's mostly cosmetics) + for (i = num_final_segments; i < num_segments; ++i) { + enc->dqm_[i] = enc->dqm_[num_final_segments - 1]; + } + } +} + +void VP8SetSegmentParams(VP8Encoder* const enc, float quality) { + int i; + int dq_uv_ac, dq_uv_dc; + const int num_segments = enc->segment_hdr_.num_segments_; + const double amp = SNS_TO_DQ * enc->config_->sns_strength / 100. / 128.; + const double Q = quality / 100.; + const double c_base = enc->config_->emulate_jpeg_size ? + QualityToJPEGCompression(Q, enc->alpha_ / 255.) : + QualityToCompression(Q); + for (i = 0; i < num_segments; ++i) { + // We modulate the base coefficient to accommodate for the quantization + // susceptibility and allow denser segments to be quantized more. + const double expn = 1. - amp * enc->dqm_[i].alpha_; + 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 unpleasant). + 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; + + SetupFilterStrength(enc); // initialize segments' filtering, eventually + + if (num_segments > 1) SimplifySegments(enc); + + SetupMatrices(enc); // finalize quantization matrices +} + +//------------------------------------------------------------------------------ +// Form the predictions in cache + +// Must be ordered using {DC_PRED, TM_PRED, V_PRED, H_PRED} as index +const uint16_t VP8I16ModeOffsets[4] = { I16DC16, I16TM16, I16VE16, I16HE16 }; +const uint16_t VP8UVModeOffsets[4] = { C8DC8, C8TM8, C8VE8, C8HE8 }; + +// Must be indexed using {B_DC_PRED -> B_HU_PRED} as index +const uint16_t VP8I4ModeOffsets[NUM_BMODES] = { + I4DC4, I4TM4, I4VE4, I4HE4, I4RD4, I4VR4, I4LD4, I4VL4, I4HD4, I4HU4 +}; + +void VP8MakeLuma16Preds(const VP8EncIterator* const it) { + const uint8_t* const left = it->x_ ? it->y_left_ : NULL; + const uint8_t* const top = it->y_ ? it->y_top_ : NULL; + VP8EncPredLuma16(it->yuv_p_, left, top); +} + +void VP8MakeChroma8Preds(const VP8EncIterator* const it) { + const uint8_t* const left = it->x_ ? it->u_left_ : NULL; + const uint8_t* const top = it->y_ ? it->uv_top_ : NULL; + VP8EncPredChroma8(it->yuv_p_, left, top); +} + +void VP8MakeIntra4Preds(const VP8EncIterator* const it) { + VP8EncPredLuma4(it->yuv_p_, it->i4_top_); +} + +//------------------------------------------------------------------------------ +// Quantize + +// Layout: +// +----+----+ +// |YYYY|UUVV| 0 +// |YYYY|UUVV| 4 +// |YYYY|....| 8 +// |YYYY|....| 12 +// +----+----+ + +const uint16_t VP8Scan[16] = { // 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, +}; + +static const uint16_t VP8ScanUV[4 + 4] = { + 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->H = 0; + rd->nz = 0; + rd->score = MAX_COST; +} + +static void CopyScore(VP8ModeScore* WEBP_RESTRICT const dst, + const VP8ModeScore* WEBP_RESTRICT const src) { + dst->D = src->D; + dst->SD = src->SD; + dst->R = src->R; + dst->H = src->H; + dst->nz = src->nz; // note that nz is not accumulated, but just copied. + dst->score = src->score; +} + +static void AddScore(VP8ModeScore* WEBP_RESTRICT const dst, + const VP8ModeScore* WEBP_RESTRICT const src) { + dst->D += src->D; + dst->SD += src->SD; + dst->R += src->R; + dst->H += src->H; + dst->nz |= src->nz; // here, new nz bits are accumulated. + dst->score += src->score; +} + +//------------------------------------------------------------------------------ +// Performs trellis-optimized quantization. + +// Trellis node +typedef struct { + int8_t prev; // best previous node + int8_t sign; // sign of coeff_i + int16_t level; // level +} Node; + +// Score state +typedef struct { + score_t score; // partial RD score + const uint16_t* costs; // shortcut to cost tables +} ScoreState; + +// 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)][(l) + MIN_DELTA]) +#define SCORE_STATE(n, l) (score_states[n][(l) + MIN_DELTA]) + +static WEBP_INLINE void SetRDScore(int lambda, VP8ModeScore* const rd) { + rd->score = (rd->R + rd->H) * lambda + RD_DISTO_MULT * (rd->D + rd->SD); +} + +static WEBP_INLINE score_t RDScoreTrellis(int lambda, score_t rate, + score_t distortion) { + return rate * lambda + RD_DISTO_MULT * distortion; +} + +// Coefficient type. +enum { TYPE_I16_AC = 0, TYPE_I16_DC = 1, TYPE_CHROMA_A = 2, TYPE_I4_AC = 3 }; + +static int TrellisQuantizeBlock(const VP8Encoder* WEBP_RESTRICT const enc, + int16_t in[16], int16_t out[16], + int ctx0, int coeff_type, + const VP8Matrix* WEBP_RESTRICT const mtx, + int lambda) { + const ProbaArray* const probas = enc->proba_.coeffs_[coeff_type]; + CostArrayPtr const costs = + (CostArrayPtr)enc->proba_.remapped_costs_[coeff_type]; + const int first = (coeff_type == TYPE_I16_AC) ? 1 : 0; + Node nodes[16][NUM_NODES]; + ScoreState score_states[2][NUM_NODES]; + ScoreState* ss_cur = &SCORE_STATE(0, MIN_DELTA); + ScoreState* ss_prev = &SCORE_STATE(1, MIN_DELTA); + int best_path[3] = {-1, -1, -1}; // store best-last/best-level/best-previous + score_t best_score; + int n, m, p, last; + + { + score_t cost; + const int thresh = mtx->q_[1] * mtx->q_[1] / 4; + const int last_proba = probas[VP8EncBands[first]][ctx0][0]; + + // compute the position of the last interesting coefficient + last = first - 1; + for (n = 15; n >= first; --n) { + const int j = kZigzag[n]; + const int err = in[j] * in[j]; + if (err > thresh) { + last = n; + break; + } + } + // 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, 0); + + // initialize source node. + for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { + const score_t rate = (ctx0 == 0) ? VP8BitCost(1, last_proba) : 0; + ss_cur[m].score = RDScoreTrellis(lambda, rate, 0); + ss_cur[m].costs = costs[first][ctx0]; + } + } + + // traverse trellis. + for (n = first; n <= last; ++n) { + const int j = kZigzag[n]; + const uint32_t Q = mtx->q_[j]; + const uint32_t iQ = mtx->iq_[j]; + const uint32_t 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); + const uint32_t coeff0 = (sign ? -in[j] : in[j]) + mtx->sharpen_[j]; + int level0 = QUANTDIV(coeff0, iQ, B); + int thresh_level = QUANTDIV(coeff0, iQ, BIAS(0x80)); + if (thresh_level > MAX_LEVEL) thresh_level = MAX_LEVEL; + if (level0 > MAX_LEVEL) level0 = MAX_LEVEL; + + { // Swap current and previous score states + ScoreState* const tmp = ss_cur; + ss_cur = ss_prev; + ss_prev = tmp; + } + + // test all alternate level values around level0. + for (m = -MIN_DELTA; m <= MAX_DELTA; ++m) { + Node* const cur = &NODE(n, m); + const int level = level0 + m; + const int ctx = (level > 2) ? 2 : level; + const int band = VP8EncBands[n + 1]; + score_t base_score; + score_t best_cur_score; + int best_prev; + score_t cost, score; + + ss_cur[m].costs = costs[n + 1][ctx]; + if (level < 0 || level > thresh_level) { + ss_cur[m].score = MAX_COST; + // Node is dead. + continue; + } + + { + // Compute delta_error = how much coding this level will + // subtract to max_error as distortion. + // Here, distortion = sum of (|coeff_i| - level_i * Q_i)^2 + const int new_error = coeff0 - level * Q; + const int delta_error = + kWeightTrellis[j] * (new_error * new_error - coeff0 * coeff0); + base_score = RDScoreTrellis(lambda, 0, delta_error); + } + + // Inspect all possible non-dead predecessors. Retain only the best one. + // The base_score is added to all scores so it is only added for the final + // value after the loop. + cost = VP8LevelCost(ss_prev[-MIN_DELTA].costs, level); + best_cur_score = + ss_prev[-MIN_DELTA].score + RDScoreTrellis(lambda, cost, 0); + best_prev = -MIN_DELTA; + for (p = -MIN_DELTA + 1; p <= MAX_DELTA; ++p) { + // Dead nodes (with ss_prev[p].score >= MAX_COST) are automatically + // eliminated since their score can't be better than the current best. + cost = VP8LevelCost(ss_prev[p].costs, level); + // Examine node assuming it's a non-terminal one. + score = ss_prev[p].score + RDScoreTrellis(lambda, cost, 0); + if (score < best_cur_score) { + best_cur_score = score; + best_prev = p; + } + } + best_cur_score += base_score; + // Store best finding in current node. + cur->sign = sign; + cur->level = level; + cur->prev = best_prev; + ss_cur[m].score = best_cur_score; + + // Now, record best terminal node (and thus best entry in the graph). + if (level != 0 && best_cur_score < best_score) { + const score_t last_pos_cost = + (n < 15) ? VP8BitCost(0, probas[band][ctx][0]) : 0; + const score_t last_pos_score = RDScoreTrellis(lambda, last_pos_cost, 0); + score = best_cur_score + last_pos_score; + if (score < best_score) { + best_score = score; + best_path[0] = n; // best eob position + best_path[1] = m; // best node index + best_path[2] = best_prev; // best predecessor + } + } + } + } + + // Fresh start + // Beware! We must preserve in[0]/out[0] value for TYPE_I16_AC case. + if (coeff_type == TYPE_I16_AC) { + memset(in + 1, 0, 15 * sizeof(*in)); + memset(out + 1, 0, 15 * sizeof(*out)); + } else { + memset(in, 0, 16 * sizeof(*in)); + memset(out, 0, 16 * 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. + int nz = 0; + int best_node = best_path[1]; + n = best_path[0]; + NODE(n, best_node).prev = best_path[2]; // force best-prev for terminal + + 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; + in[j] = out[n] * mtx->q_[j]; + best_node = node->prev; + } + return (nz != 0); + } +} + +#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* WEBP_RESTRICT const it, + VP8ModeScore* WEBP_RESTRICT const rd, + uint8_t* WEBP_RESTRICT 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_ENC; + 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 += 2) { + VP8FTransform2(src + VP8Scan[n], ref + VP8Scan[n], tmp[n]); + } + VP8FTransformWHT(tmp[0], dc_tmp); + nz |= VP8EncQuantizeBlockWHT(dc_tmp, rd->y_dc_levels, &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( + enc, tmp[n], rd->y_ac_levels[n], ctx, TYPE_I16_AC, &dqm->y1_, + dqm->lambda_trellis_i16_); + it->top_nz_[x] = it->left_nz_[y] = non_zero; + rd->y_ac_levels[n][0] = 0; + nz |= non_zero << n; + } + } + } else { + for (n = 0; n < 16; n += 2) { + // Zero-out the first coeff, so that: a) nz is correct below, and + // b) finding 'last' non-zero coeffs in SetResidualCoeffs() is simplified. + tmp[n][0] = tmp[n + 1][0] = 0; + nz |= VP8EncQuantize2Blocks(tmp[n], rd->y_ac_levels[n], &dqm->y1_) << n; + assert(rd->y_ac_levels[n + 0][0] == 0); + assert(rd->y_ac_levels[n + 1][0] == 0); + } + } + + // Transform back + VP8TransformWHT(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* WEBP_RESTRICT const it, + int16_t levels[16], + const uint8_t* WEBP_RESTRICT const src, + uint8_t* WEBP_RESTRICT 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(enc, tmp, levels, ctx, TYPE_I4_AC, &dqm->y1_, + dqm->lambda_trellis_i4_); + } else { + nz = VP8EncQuantizeBlock(tmp, levels, &dqm->y1_); + } + VP8ITransform(ref, tmp, yuv_out, 0); + return nz; +} + +//------------------------------------------------------------------------------ +// DC-error diffusion + +// Diffusion weights. We under-correct a bit (15/16th of the error is actually +// diffused) to avoid 'rainbow' chessboard pattern of blocks at q~=0. +#define C1 7 // fraction of error sent to the 4x4 block below +#define C2 8 // fraction of error sent to the 4x4 block on the right +#define DSHIFT 4 +#define DSCALE 1 // storage descaling, needed to make the error fit int8_t + +// Quantize as usual, but also compute and return the quantization error. +// Error is already divided by DSHIFT. +static int QuantizeSingle(int16_t* WEBP_RESTRICT const v, + const VP8Matrix* WEBP_RESTRICT const mtx) { + int V = *v; + const int sign = (V < 0); + if (sign) V = -V; + if (V > (int)mtx->zthresh_[0]) { + const int qV = QUANTDIV(V, mtx->iq_[0], mtx->bias_[0]) * mtx->q_[0]; + const int err = (V - qV); + *v = sign ? -qV : qV; + return (sign ? -err : err) >> DSCALE; + } + *v = 0; + return (sign ? -V : V) >> DSCALE; +} + +static void CorrectDCValues(const VP8EncIterator* WEBP_RESTRICT const it, + const VP8Matrix* WEBP_RESTRICT const mtx, + int16_t tmp[][16], + VP8ModeScore* WEBP_RESTRICT const rd) { + // | top[0] | top[1] + // --------+--------+--------- + // left[0] | tmp[0] tmp[1] <-> err0 err1 + // left[1] | tmp[2] tmp[3] err2 err3 + // + // Final errors {err1,err2,err3} are preserved and later restored + // as top[]/left[] on the next block. + int ch; + for (ch = 0; ch <= 1; ++ch) { + const int8_t* const top = it->top_derr_[it->x_][ch]; + const int8_t* const left = it->left_derr_[ch]; + int16_t (* const c)[16] = &tmp[ch * 4]; + int err0, err1, err2, err3; + c[0][0] += (C1 * top[0] + C2 * left[0]) >> (DSHIFT - DSCALE); + err0 = QuantizeSingle(&c[0][0], mtx); + c[1][0] += (C1 * top[1] + C2 * err0) >> (DSHIFT - DSCALE); + err1 = QuantizeSingle(&c[1][0], mtx); + c[2][0] += (C1 * err0 + C2 * left[1]) >> (DSHIFT - DSCALE); + err2 = QuantizeSingle(&c[2][0], mtx); + c[3][0] += (C1 * err1 + C2 * err2) >> (DSHIFT - DSCALE); + err3 = QuantizeSingle(&c[3][0], mtx); + // error 'err' is bounded by mtx->q_[0] which is 132 at max. Hence + // err >> DSCALE will fit in an int8_t type if DSCALE>=1. + assert(abs(err1) <= 127 && abs(err2) <= 127 && abs(err3) <= 127); + rd->derr[ch][0] = (int8_t)err1; + rd->derr[ch][1] = (int8_t)err2; + rd->derr[ch][2] = (int8_t)err3; + } +} + +static void StoreDiffusionErrors(VP8EncIterator* WEBP_RESTRICT const it, + const VP8ModeScore* WEBP_RESTRICT const rd) { + int ch; + for (ch = 0; ch <= 1; ++ch) { + int8_t* const top = it->top_derr_[it->x_][ch]; + int8_t* const left = it->left_derr_[ch]; + left[0] = rd->derr[ch][0]; // restore err1 + left[1] = 3 * rd->derr[ch][2] >> 2; // ... 3/4th of err3 + top[0] = rd->derr[ch][1]; // ... err2 + top[1] = rd->derr[ch][2] - left[1]; // ... 1/4th of err3. + } +} + +#undef C1 +#undef C2 +#undef DSHIFT +#undef DSCALE + +//------------------------------------------------------------------------------ + +static int ReconstructUV(VP8EncIterator* WEBP_RESTRICT const it, + VP8ModeScore* WEBP_RESTRICT const rd, + uint8_t* WEBP_RESTRICT 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_ENC; + 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 += 2) { + VP8FTransform2(src + VP8ScanUV[n], ref + VP8ScanUV[n], tmp[n]); + } + if (it->top_derr_ != NULL) CorrectDCValues(it, &dqm->uv_, tmp, rd); + + 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( + enc, tmp[n], rd->uv_levels[n], ctx, TYPE_CHROMA_A, &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 += 2) { + nz |= VP8EncQuantize2Blocks(tmp[n], rd->uv_levels[n], &dqm->uv_) << n; + } + } + + for (n = 0; n < 8; n += 2) { + VP8ITransform(ref + VP8ScanUV[n], tmp[n], yuv_out + VP8ScanUV[n], 1); + } + return (nz << 16); +} + +//------------------------------------------------------------------------------ +// RD-opt decision. Reconstruct each modes, evalue distortion and bit-cost. +// Pick the mode is lower RD-cost = Rate + lambda * Distortion. + +static void StoreMaxDelta(VP8SegmentInfo* const dqm, const int16_t DCs[16]) { + // We look at the first three AC coefficients to determine what is the average + // delta between each sub-4x4 block. + const int v0 = abs(DCs[1]); + const int v1 = abs(DCs[2]); + const int v2 = abs(DCs[4]); + int max_v = (v1 > v0) ? v1 : v0; + max_v = (v2 > max_v) ? v2 : max_v; + if (max_v > dqm->max_edge_) dqm->max_edge_ = max_v; +} + +static void SwapModeScore(VP8ModeScore** a, VP8ModeScore** b) { + VP8ModeScore* const tmp = *a; + *a = *b; + *b = tmp; +} + +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* WEBP_RESTRICT const it, + VP8ModeScore* WEBP_RESTRICT rd) { + const int kNumBlocks = 16; + VP8SegmentInfo* const dqm = &it->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_ENC; + VP8ModeScore rd_tmp; + VP8ModeScore* rd_cur = &rd_tmp; + VP8ModeScore* rd_best = rd; + int mode; + int is_flat = IsFlatSource16(it->yuv_in_ + Y_OFF_ENC); + + rd->mode_i16 = -1; + for (mode = 0; mode < NUM_PRED_MODES; ++mode) { + uint8_t* const tmp_dst = it->yuv_out2_ + Y_OFF_ENC; // scratch buffer + rd_cur->mode_i16 = mode; + + // Reconstruct + rd_cur->nz = ReconstructIntra16(it, rd_cur, tmp_dst, mode); + + // Measure RD-score + rd_cur->D = VP8SSE16x16(src, tmp_dst); + rd_cur->SD = + tlambda ? MULT_8B(tlambda, VP8TDisto16x16(src, tmp_dst, kWeightY)) : 0; + rd_cur->H = VP8FixedCostsI16[mode]; + rd_cur->R = VP8GetCostLuma16(it, rd_cur); + if (is_flat) { + // refine the first impression (which was in pixel space) + is_flat = IsFlat(rd_cur->y_ac_levels[0], kNumBlocks, FLATNESS_LIMIT_I16); + if (is_flat) { + // Block is very flat. We put emphasis on the distortion being very low! + rd_cur->D *= 2; + rd_cur->SD *= 2; + } + } + + // Since we always examine Intra16 first, we can overwrite *rd directly. + SetRDScore(lambda, rd_cur); + if (mode == 0 || rd_cur->score < rd_best->score) { + SwapModeScore(&rd_cur, &rd_best); + SwapOut(it); + } + } + if (rd_best != rd) { + memcpy(rd, rd_best, sizeof(*rd)); + } + SetRDScore(dqm->lambda_mode_, rd); // finalize score for mode decision. + VP8SetIntra16Mode(it, rd->mode_i16); + + // we have a blocky macroblock (only DCs are non-zero) with fairly high + // distortion, record max delta so we can later adjust the minimal filtering + // strength needed to smooth these blocks out. + if ((rd->nz & 0x100ffff) == 0x1000000 && rd->D > dqm->min_disto_) { + StoreMaxDelta(dqm, rd->y_dc_levels); + } +} + +//------------------------------------------------------------------------------ + +// return the cost array corresponding to the surrounding prediction modes. +static const uint16_t* GetCostModeI4(VP8EncIterator* WEBP_RESTRICT 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* WEBP_RESTRICT const it, + VP8ModeScore* WEBP_RESTRICT 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_ENC; + uint8_t* const best_blocks = it->yuv_out2_ + Y_OFF_ENC; + int total_header_bits = 0; + VP8ModeScore rd_best; + + if (enc->max_i4_header_bits_ == 0) { + return 0; + } + + InitScore(&rd_best); + rd_best.H = 211; // '211' is the value of VP8BitCost(0, 145) + SetRDScore(dqm->lambda_mode_, &rd_best); + VP8IteratorStartI4(it); + do { + const int kNumBlocks = 1; + 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.H = mode_costs[mode]; + + // Add flatness penalty, to avoid flat area to be mispredicted + // by a complex mode. + if (mode > 0 && IsFlat(tmp_levels, kNumBlocks, FLATNESS_LIMIT_I4)) { + rd_tmp.R = FLATNESS_PENALTY * kNumBlocks; + } else { + rd_tmp.R = 0; + } + + // early-out check + SetRDScore(lambda, &rd_tmp); + if (best_mode >= 0 && rd_tmp.score >= rd_i4.score) continue; + + // finish computing score + rd_tmp.R += VP8GetCostLuma4(it, tmp_levels); + 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(rd_best.y_ac_levels[it->i4_])); + } + } + SetRDScore(dqm->lambda_mode_, &rd_i4); + AddScore(&rd_best, &rd_i4); + if (rd_best.score >= rd->score) { + return 0; + } + total_header_bits += (int)rd_i4.H; // <- equal to mode_costs[best_mode]; + if (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* WEBP_RESTRICT const it, + VP8ModeScore* WEBP_RESTRICT const rd) { + const int kNumBlocks = 8; + const VP8SegmentInfo* const dqm = &it->enc_->dqm_[it->mb_->segment_]; + const int lambda = dqm->lambda_uv_; + const uint8_t* const src = it->yuv_in_ + U_OFF_ENC; + uint8_t* tmp_dst = it->yuv_out2_ + U_OFF_ENC; // scratch buffer + uint8_t* dst0 = it->yuv_out_ + U_OFF_ENC; + uint8_t* dst = dst0; + VP8ModeScore rd_best; + int mode; + + rd->mode_uv = -1; + InitScore(&rd_best); + for (mode = 0; mode < NUM_PRED_MODES; ++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; // not calling TDisto here: it tends to flatten areas. + rd_uv.H = VP8FixedCostsUV[mode]; + rd_uv.R = VP8GetCostUV(it, &rd_uv); + if (mode > 0 && IsFlat(rd_uv.uv_levels[0], kNumBlocks, FLATNESS_LIMIT_UV)) { + rd_uv.R += FLATNESS_PENALTY * kNumBlocks; + } + + 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)); + if (it->top_derr_ != NULL) { + memcpy(rd->derr, rd_uv.derr, sizeof(rd_uv.derr)); + } + SwapPtr(&dst, &tmp_dst); + } + } + VP8SetIntraUVMode(it, rd->mode_uv); + AddScore(rd, &rd_best); + if (dst != dst0) { // copy 16x8 block if needed + VP8Copy16x8(dst, dst0); + } + if (it->top_derr_ != NULL) { // store diffusion errors for next block + StoreDiffusionErrors(it, rd); + } +} + +//------------------------------------------------------------------------------ +// Final reconstruction and quantization. + +static void SimpleQuantize(VP8EncIterator* WEBP_RESTRICT const it, + VP8ModeScore* WEBP_RESTRICT const rd) { + const VP8Encoder* const enc = it->enc_; + const int is_i16 = (it->mb_->type_ == 1); + int nz = 0; + + if (is_i16) { + nz = ReconstructIntra16(it, rd, it->yuv_out_ + Y_OFF_ENC, 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_ENC + VP8Scan[it->i4_]; + uint8_t* const dst = it->yuv_out_ + Y_OFF_ENC + 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_ENC)); + } + + nz |= ReconstructUV(it, rd, it->yuv_out_ + U_OFF_ENC, it->mb_->uv_mode_); + rd->nz = nz; +} + +// Refine intra16/intra4 sub-modes based on distortion only (not rate). +static void RefineUsingDistortion(VP8EncIterator* WEBP_RESTRICT const it, + int try_both_modes, int refine_uv_mode, + VP8ModeScore* WEBP_RESTRICT const rd) { + score_t best_score = MAX_COST; + int nz = 0; + int mode; + int is_i16 = try_both_modes || (it->mb_->type_ == 1); + + const VP8SegmentInfo* const dqm = &it->enc_->dqm_[it->mb_->segment_]; + // Some empiric constants, of approximate order of magnitude. + const int lambda_d_i16 = 106; + const int lambda_d_i4 = 11; + const int lambda_d_uv = 120; + score_t score_i4 = dqm->i4_penalty_; + score_t i4_bit_sum = 0; + const score_t bit_limit = try_both_modes ? it->enc_->mb_header_limit_ + : MAX_COST; // no early-out allowed + + if (is_i16) { // First, evaluate Intra16 distortion + int best_mode = -1; + const uint8_t* const src = it->yuv_in_ + Y_OFF_ENC; + for (mode = 0; mode < NUM_PRED_MODES; ++mode) { + const uint8_t* const ref = it->yuv_p_ + VP8I16ModeOffsets[mode]; + const score_t score = (score_t)VP8SSE16x16(src, ref) * RD_DISTO_MULT + + VP8FixedCostsI16[mode] * lambda_d_i16; + if (mode > 0 && VP8FixedCostsI16[mode] > bit_limit) { + continue; + } + + if (score < best_score) { + best_mode = mode; + best_score = score; + } + } + if (it->x_ == 0 || it->y_ == 0) { + // avoid starting a checkerboard resonance from the border. See bug #432. + if (IsFlatSource16(src)) { + best_mode = (it->x_ == 0) ? 0 : 2; + try_both_modes = 0; // stick to i16 + } + } + VP8SetIntra16Mode(it, best_mode); + // we'll reconstruct later, if i16 mode actually gets selected + } + + // Next, evaluate Intra4 + if (try_both_modes || !is_i16) { + // We don't evaluate the rate here, but just account for it through a + // constant penalty (i4 mode usually needs more bits compared to i16). + is_i16 = 0; + VP8IteratorStartI4(it); + do { + int best_i4_mode = -1; + score_t best_i4_score = MAX_COST; + const uint8_t* const src = it->yuv_in_ + Y_OFF_ENC + VP8Scan[it->i4_]; + const uint16_t* const mode_costs = GetCostModeI4(it, rd->modes_i4); + + VP8MakeIntra4Preds(it); + for (mode = 0; mode < NUM_BMODES; ++mode) { + const uint8_t* const ref = it->yuv_p_ + VP8I4ModeOffsets[mode]; + const score_t score = VP8SSE4x4(src, ref) * RD_DISTO_MULT + + mode_costs[mode] * lambda_d_i4; + if (score < best_i4_score) { + best_i4_mode = mode; + best_i4_score = score; + } + } + i4_bit_sum += mode_costs[best_i4_mode]; + rd->modes_i4[it->i4_] = best_i4_mode; + score_i4 += best_i4_score; + if (score_i4 >= best_score || i4_bit_sum > bit_limit) { + // Intra4 won't be better than Intra16. Bail out and pick Intra16. + is_i16 = 1; + break; + } else { // reconstruct partial block inside yuv_out2_ buffer + uint8_t* const tmp_dst = it->yuv_out2_ + Y_OFF_ENC + VP8Scan[it->i4_]; + nz |= ReconstructIntra4(it, rd->y_ac_levels[it->i4_], + src, tmp_dst, best_i4_mode) << it->i4_; + } + } while (VP8IteratorRotateI4(it, it->yuv_out2_ + Y_OFF_ENC)); + } + + // Final reconstruction, depending on which mode is selected. + if (!is_i16) { + VP8SetIntra4Mode(it, rd->modes_i4); + SwapOut(it); + best_score = score_i4; + } else { + nz = ReconstructIntra16(it, rd, it->yuv_out_ + Y_OFF_ENC, it->preds_[0]); + } + + // ... and UV! + if (refine_uv_mode) { + int best_mode = -1; + score_t best_uv_score = MAX_COST; + const uint8_t* const src = it->yuv_in_ + U_OFF_ENC; + for (mode = 0; mode < NUM_PRED_MODES; ++mode) { + const uint8_t* const ref = it->yuv_p_ + VP8UVModeOffsets[mode]; + const score_t score = VP8SSE16x8(src, ref) * RD_DISTO_MULT + + VP8FixedCostsUV[mode] * lambda_d_uv; + if (score < best_uv_score) { + best_mode = mode; + best_uv_score = score; + } + } + VP8SetIntraUVMode(it, best_mode); + } + nz |= ReconstructUV(it, rd, it->yuv_out_ + U_OFF_ENC, it->mb_->uv_mode_); + + rd->nz = nz; + rd->score = best_score; +} + +//------------------------------------------------------------------------------ +// Entry point + +int VP8Decimate(VP8EncIterator* WEBP_RESTRICT const it, + VP8ModeScore* WEBP_RESTRICT const rd, + VP8RDLevel rd_opt) { + int is_skipped; + const int method = it->enc_->method_; + + InitScore(rd); + + // We can perform predictions for Luma16x16 and Chroma8x8 already. + // Luma4x4 predictions needs to be done as-we-go. + VP8MakeLuma16Preds(it); + VP8MakeChroma8Preds(it); + + if (rd_opt > RD_OPT_NONE) { + it->do_trellis_ = (rd_opt >= RD_OPT_TRELLIS_ALL); + PickBestIntra16(it, rd); + if (method >= 2) { + PickBestIntra4(it, rd); + } + PickBestUV(it, rd); + if (rd_opt == RD_OPT_TRELLIS) { // finish off with trellis-optim now + it->do_trellis_ = 1; + SimpleQuantize(it, rd); + } + } else { + // At this point we have heuristically decided intra16 / intra4. + // For method >= 2, pick the best intra4/intra16 based on SSE (~tad slower). + // For method <= 1, we don't re-examine the decision but just go ahead with + // quantization/reconstruction. + RefineUsingDistortion(it, (method >= 2), (method >= 1), rd); + } + is_skipped = (rd->nz == 0); + VP8SetSkip(it, is_skipped); + return is_skipped; +} |