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Diffstat (limited to 'thirdparty/astcenc/astcenc_pick_best_endpoint_format.cpp')
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diff --git a/thirdparty/astcenc/astcenc_pick_best_endpoint_format.cpp b/thirdparty/astcenc/astcenc_pick_best_endpoint_format.cpp new file mode 100644 index 0000000000..f25140d4c7 --- /dev/null +++ b/thirdparty/astcenc/astcenc_pick_best_endpoint_format.cpp @@ -0,0 +1,1350 @@ +// SPDX-License-Identifier: Apache-2.0 +// ---------------------------------------------------------------------------- +// Copyright 2011-2022 Arm Limited +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not +// use this file except in compliance with the License. You may obtain a copy +// of the License at: +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +// License for the specific language governing permissions and limitations +// under the License. +// ---------------------------------------------------------------------------- + +#if !defined(ASTCENC_DECOMPRESS_ONLY) + +/** + * @brief Functions for finding best endpoint format. + * + * We assume there are two independent sources of error in any given partition: + * + * - Encoding choice errors + * - Quantization errors + * + * Encoding choice errors are caused by encoder decisions. For example: + * + * - Using luminance instead of separate RGB components. + * - Using a constant 1.0 alpha instead of storing an alpha component. + * - Using RGB+scale instead of storing two full RGB endpoints. + * + * Quantization errors occur due to the limited precision we use for storage. These errors generally + * scale with quantization level, but are not actually independent of color encoding. In particular: + * + * - If we can use offset encoding then quantization error is halved. + * - If we can use blue-contraction then quantization error for RG is halved. + * - If we use HDR endpoints the quantization error is higher. + * + * Apart from these effects, we assume the error is proportional to the quantization step size. + */ + + +#include "astcenc_internal.h" +#include "astcenc_vecmathlib.h" + +#include <assert.h> + +/** + * @brief Compute the errors of the endpoint line options for one partition. + * + * Uncorrelated data assumes storing completely independent RGBA channels for each endpoint. Same + * chroma data assumes storing RGBA endpoints which pass though the origin (LDR only). RGBL data + * assumes storing RGB + lumashift (HDR only). Luminance error assumes storing RGB channels as a + * single value. + * + * + * @param pi The partition info data. + * @param partition_index The partition index to compule the error for. + * @param blk The image block. + * @param uncor_pline The endpoint line assuming uncorrelated endpoints. + * @param[out] uncor_err The computed error for the uncorrelated endpoint line. + * @param samec_pline The endpoint line assuming the same chroma for both endpoints. + * @param[out] samec_err The computed error for the uncorrelated endpoint line. + * @param rgbl_pline The endpoint line assuming RGB + lumashift data. + * @param[out] rgbl_err The computed error for the RGB + lumashift endpoint line. + * @param l_pline The endpoint line assuming luminance data. + * @param[out] l_err The computed error for the luminance endpoint line. + * @param[out] a_drop_err The computed error for dropping the alpha component. + */ +static void compute_error_squared_rgb_single_partition( + const partition_info& pi, + int partition_index, + const image_block& blk, + const processed_line3& uncor_pline, + float& uncor_err, + const processed_line3& samec_pline, + float& samec_err, + const processed_line3& rgbl_pline, + float& rgbl_err, + const processed_line3& l_pline, + float& l_err, + float& a_drop_err +) { + vfloat4 ews = blk.channel_weight; + + unsigned int texel_count = pi.partition_texel_count[partition_index]; + const uint8_t* texel_indexes = pi.texels_of_partition[partition_index]; + promise(texel_count > 0); + + vfloatacc a_drop_errv = vfloatacc::zero(); + vfloat default_a(blk.get_default_alpha()); + + vfloatacc uncor_errv = vfloatacc::zero(); + vfloat uncor_bs0(uncor_pline.bs.lane<0>()); + vfloat uncor_bs1(uncor_pline.bs.lane<1>()); + vfloat uncor_bs2(uncor_pline.bs.lane<2>()); + + vfloat uncor_amod0(uncor_pline.amod.lane<0>()); + vfloat uncor_amod1(uncor_pline.amod.lane<1>()); + vfloat uncor_amod2(uncor_pline.amod.lane<2>()); + + vfloatacc samec_errv = vfloatacc::zero(); + vfloat samec_bs0(samec_pline.bs.lane<0>()); + vfloat samec_bs1(samec_pline.bs.lane<1>()); + vfloat samec_bs2(samec_pline.bs.lane<2>()); + + vfloatacc rgbl_errv = vfloatacc::zero(); + vfloat rgbl_bs0(rgbl_pline.bs.lane<0>()); + vfloat rgbl_bs1(rgbl_pline.bs.lane<1>()); + vfloat rgbl_bs2(rgbl_pline.bs.lane<2>()); + + vfloat rgbl_amod0(rgbl_pline.amod.lane<0>()); + vfloat rgbl_amod1(rgbl_pline.amod.lane<1>()); + vfloat rgbl_amod2(rgbl_pline.amod.lane<2>()); + + vfloatacc l_errv = vfloatacc::zero(); + vfloat l_bs0(l_pline.bs.lane<0>()); + vfloat l_bs1(l_pline.bs.lane<1>()); + vfloat l_bs2(l_pline.bs.lane<2>()); + + vint lane_ids = vint::lane_id(); + for (unsigned int i = 0; i < texel_count; i += ASTCENC_SIMD_WIDTH) + { + vint tix(texel_indexes + i); + + vmask mask = lane_ids < vint(texel_count); + lane_ids += vint(ASTCENC_SIMD_WIDTH); + + // Compute the error that arises from just ditching alpha + vfloat data_a = gatherf(blk.data_a, tix); + vfloat alpha_diff = data_a - default_a; + alpha_diff = alpha_diff * alpha_diff; + + haccumulate(a_drop_errv, alpha_diff, mask); + + vfloat data_r = gatherf(blk.data_r, tix); + vfloat data_g = gatherf(blk.data_g, tix); + vfloat data_b = gatherf(blk.data_b, tix); + + // Compute uncorrelated error + vfloat param = data_r * uncor_bs0 + + data_g * uncor_bs1 + + data_b * uncor_bs2; + + vfloat dist0 = (uncor_amod0 + param * uncor_bs0) - data_r; + vfloat dist1 = (uncor_amod1 + param * uncor_bs1) - data_g; + vfloat dist2 = (uncor_amod2 + param * uncor_bs2) - data_b; + + vfloat error = dist0 * dist0 * ews.lane<0>() + + dist1 * dist1 * ews.lane<1>() + + dist2 * dist2 * ews.lane<2>(); + + haccumulate(uncor_errv, error, mask); + + // Compute same chroma error - no "amod", its always zero + param = data_r * samec_bs0 + + data_g * samec_bs1 + + data_b * samec_bs2; + + dist0 = (param * samec_bs0) - data_r; + dist1 = (param * samec_bs1) - data_g; + dist2 = (param * samec_bs2) - data_b; + + error = dist0 * dist0 * ews.lane<0>() + + dist1 * dist1 * ews.lane<1>() + + dist2 * dist2 * ews.lane<2>(); + + haccumulate(samec_errv, error, mask); + + // Compute rgbl error + param = data_r * rgbl_bs0 + + data_g * rgbl_bs1 + + data_b * rgbl_bs2; + + dist0 = (rgbl_amod0 + param * rgbl_bs0) - data_r; + dist1 = (rgbl_amod1 + param * rgbl_bs1) - data_g; + dist2 = (rgbl_amod2 + param * rgbl_bs2) - data_b; + + error = dist0 * dist0 * ews.lane<0>() + + dist1 * dist1 * ews.lane<1>() + + dist2 * dist2 * ews.lane<2>(); + + haccumulate(rgbl_errv, error, mask); + + // Compute luma error - no "amod", its always zero + param = data_r * l_bs0 + + data_g * l_bs1 + + data_b * l_bs2; + + dist0 = (param * l_bs0) - data_r; + dist1 = (param * l_bs1) - data_g; + dist2 = (param * l_bs2) - data_b; + + error = dist0 * dist0 * ews.lane<0>() + + dist1 * dist1 * ews.lane<1>() + + dist2 * dist2 * ews.lane<2>(); + + haccumulate(l_errv, error, mask); + } + + a_drop_err = hadd_s(a_drop_errv) * ews.lane<3>(); + uncor_err = hadd_s(uncor_errv); + samec_err = hadd_s(samec_errv); + rgbl_err = hadd_s(rgbl_errv); + l_err = hadd_s(l_errv); +} + +/** + * @brief For a given set of input colors and partitioning determine endpoint encode errors. + * + * This function determines the color error that results from RGB-scale encoding (LDR only), + * RGB-lumashift encoding (HDR only), luminance-encoding, and alpha drop. Also determines whether + * the endpoints are eligible for offset encoding or blue-contraction + * + * @param blk The image block. + * @param pi The partition info data. + * @param ep The idealized endpoints. + * @param[out] eci The resulting encoding choice error metrics. + */ +static void compute_encoding_choice_errors( + const image_block& blk, + const partition_info& pi, + const endpoints& ep, + encoding_choice_errors eci[BLOCK_MAX_PARTITIONS]) +{ + int partition_count = pi.partition_count; + promise(partition_count > 0); + + partition_metrics pms[BLOCK_MAX_PARTITIONS]; + + compute_avgs_and_dirs_3_comp_rgb(pi, blk, pms); + + for (int i = 0; i < partition_count; i++) + { + partition_metrics& pm = pms[i]; + + line3 uncor_rgb_lines; + line3 samec_rgb_lines; // for LDR-RGB-scale + line3 rgb_luma_lines; // for HDR-RGB-scale + + processed_line3 uncor_rgb_plines; + processed_line3 samec_rgb_plines; + processed_line3 rgb_luma_plines; + processed_line3 luminance_plines; + + float uncorr_rgb_error; + float samechroma_rgb_error; + float rgb_luma_error; + float luminance_rgb_error; + float alpha_drop_error; + + uncor_rgb_lines.a = pm.avg; + uncor_rgb_lines.b = normalize_safe(pm.dir, unit3()); + + samec_rgb_lines.a = vfloat4::zero(); + samec_rgb_lines.b = normalize_safe(pm.avg, unit3()); + + rgb_luma_lines.a = pm.avg; + rgb_luma_lines.b = unit3(); + + uncor_rgb_plines.amod = uncor_rgb_lines.a - uncor_rgb_lines.b * dot3(uncor_rgb_lines.a, uncor_rgb_lines.b); + uncor_rgb_plines.bs = uncor_rgb_lines.b; + + // Same chroma always goes though zero, so this is simpler than the others + samec_rgb_plines.amod = vfloat4::zero(); + samec_rgb_plines.bs = samec_rgb_lines.b; + + rgb_luma_plines.amod = rgb_luma_lines.a - rgb_luma_lines.b * dot3(rgb_luma_lines.a, rgb_luma_lines.b); + rgb_luma_plines.bs = rgb_luma_lines.b; + + // Luminance always goes though zero, so this is simpler than the others + luminance_plines.amod = vfloat4::zero(); + luminance_plines.bs = unit3(); + + compute_error_squared_rgb_single_partition( + pi, i, blk, + uncor_rgb_plines, uncorr_rgb_error, + samec_rgb_plines, samechroma_rgb_error, + rgb_luma_plines, rgb_luma_error, + luminance_plines, luminance_rgb_error, + alpha_drop_error); + + // Determine if we can offset encode RGB lanes + vfloat4 endpt0 = ep.endpt0[i]; + vfloat4 endpt1 = ep.endpt1[i]; + vfloat4 endpt_diff = abs(endpt1 - endpt0); + vmask4 endpt_can_offset = endpt_diff < vfloat4(0.12f * 65535.0f); + bool can_offset_encode = (mask(endpt_can_offset) & 0x7) == 0x7; + + // Store out the settings + eci[i].rgb_scale_error = (samechroma_rgb_error - uncorr_rgb_error) * 0.7f; // empirical + eci[i].rgb_luma_error = (rgb_luma_error - uncorr_rgb_error) * 1.5f; // wild guess + eci[i].luminance_error = (luminance_rgb_error - uncorr_rgb_error) * 3.0f; // empirical + eci[i].alpha_drop_error = alpha_drop_error * 3.0f; + eci[i].can_offset_encode = can_offset_encode; + eci[i].can_blue_contract = !blk.is_luminance(); + } +} + +/** + * @brief For a given partition compute the error for every endpoint integer count and quant level. + * + * @param encode_hdr_rgb @c true if using HDR for RGB, @c false for LDR. + * @param encode_hdr_alpha @c true if using HDR for alpha, @c false for LDR. + * @param partition_index The partition index. + * @param pi The partition info. + * @param eci The encoding choice error metrics. + * @param ep The idealized endpoints. + * @param error_weight The resulting encoding choice error metrics. + * @param[out] best_error The best error for each integer count and quant level. + * @param[out] format_of_choice The preferred endpoint format for each integer count and quant level. + */ +static void compute_color_error_for_every_integer_count_and_quant_level( + bool encode_hdr_rgb, + bool encode_hdr_alpha, + int partition_index, + const partition_info& pi, + const encoding_choice_errors& eci, + const endpoints& ep, + vfloat4 error_weight, + float best_error[21][4], + uint8_t format_of_choice[21][4] +) { + int partition_size = pi.partition_texel_count[partition_index]; + + static const float baseline_quant_error[21 - QUANT_6] { + (65536.0f * 65536.0f / 18.0f) / (5 * 5), + (65536.0f * 65536.0f / 18.0f) / (7 * 7), + (65536.0f * 65536.0f / 18.0f) / (9 * 9), + (65536.0f * 65536.0f / 18.0f) / (11 * 11), + (65536.0f * 65536.0f / 18.0f) / (15 * 15), + (65536.0f * 65536.0f / 18.0f) / (19 * 19), + (65536.0f * 65536.0f / 18.0f) / (23 * 23), + (65536.0f * 65536.0f / 18.0f) / (31 * 31), + (65536.0f * 65536.0f / 18.0f) / (39 * 39), + (65536.0f * 65536.0f / 18.0f) / (47 * 47), + (65536.0f * 65536.0f / 18.0f) / (63 * 63), + (65536.0f * 65536.0f / 18.0f) / (79 * 79), + (65536.0f * 65536.0f / 18.0f) / (95 * 95), + (65536.0f * 65536.0f / 18.0f) / (127 * 127), + (65536.0f * 65536.0f / 18.0f) / (159 * 159), + (65536.0f * 65536.0f / 18.0f) / (191 * 191), + (65536.0f * 65536.0f / 18.0f) / (255 * 255) + }; + + vfloat4 ep0 = ep.endpt0[partition_index]; + vfloat4 ep1 = ep.endpt1[partition_index]; + + float ep1_min = hmin_rgb_s(ep1); + ep1_min = astc::max(ep1_min, 0.0f); + + float error_weight_rgbsum = hadd_rgb_s(error_weight); + + float range_upper_limit_rgb = encode_hdr_rgb ? 61440.0f : 65535.0f; + float range_upper_limit_alpha = encode_hdr_alpha ? 61440.0f : 65535.0f; + + // It is possible to get endpoint colors significantly outside [0,upper-limit] even if the + // input data are safely contained in [0,upper-limit]; we need to add an error term for this + vfloat4 offset(range_upper_limit_rgb, range_upper_limit_rgb, range_upper_limit_rgb, range_upper_limit_alpha); + vfloat4 ep0_range_error_high = max(ep0 - offset, 0.0f); + vfloat4 ep1_range_error_high = max(ep1 - offset, 0.0f); + + vfloat4 ep0_range_error_low = min(ep0, 0.0f); + vfloat4 ep1_range_error_low = min(ep1, 0.0f); + + vfloat4 sum_range_error = + (ep0_range_error_low * ep0_range_error_low) + + (ep1_range_error_low * ep1_range_error_low) + + (ep0_range_error_high * ep0_range_error_high) + + (ep1_range_error_high * ep1_range_error_high); + + float rgb_range_error = dot3_s(sum_range_error, error_weight) + * 0.5f * static_cast<float>(partition_size); + float alpha_range_error = sum_range_error.lane<3>() * error_weight.lane<3>() + * 0.5f * static_cast<float>(partition_size); + + if (encode_hdr_rgb) + { + + // Collect some statistics + float af, cf; + if (ep1.lane<0>() > ep1.lane<1>() && ep1.lane<0>() > ep1.lane<2>()) + { + af = ep1.lane<0>(); + cf = ep1.lane<0>() - ep0.lane<0>(); + } + else if (ep1.lane<1>() > ep1.lane<2>()) + { + af = ep1.lane<1>(); + cf = ep1.lane<1>() - ep0.lane<1>(); + } + else + { + af = ep1.lane<2>(); + cf = ep1.lane<2>() - ep0.lane<2>(); + } + + // Estimate of color-component spread in high endpoint color + float bf = af - ep1_min; + vfloat4 prd = (ep1 - vfloat4(cf)).swz<0, 1, 2>(); + vfloat4 pdif = prd - ep0.swz<0, 1, 2>(); + // Estimate of color-component spread in low endpoint color + float df = hmax_s(abs(pdif)); + + int b = static_cast<int>(bf); + int c = static_cast<int>(cf); + int d = static_cast<int>(df); + + // Determine which one of the 6 submodes is likely to be used in case of an RGBO-mode + int rgbo_mode = 5; // 7 bits per component + // mode 4: 8 7 6 + if (b < 32768 && c < 16384) + { + rgbo_mode = 4; + } + + // mode 3: 9 6 7 + if (b < 8192 && c < 16384) + { + rgbo_mode = 3; + } + + // mode 2: 10 5 8 + if (b < 2048 && c < 16384) + { + rgbo_mode = 2; + } + + // mode 1: 11 6 5 + if (b < 2048 && c < 1024) + { + rgbo_mode = 1; + } + + // mode 0: 11 5 7 + if (b < 1024 && c < 4096) + { + rgbo_mode = 0; + } + + // Determine which one of the 9 submodes is likely to be used in case of an RGB-mode. + int rgb_mode = 8; // 8 bits per component, except 7 bits for blue + + // mode 0: 9 7 6 7 + if (b < 16384 && c < 8192 && d < 8192) + { + rgb_mode = 0; + } + + // mode 1: 9 8 6 6 + if (b < 32768 && c < 8192 && d < 4096) + { + rgb_mode = 1; + } + + // mode 2: 10 6 7 7 + if (b < 4096 && c < 8192 && d < 4096) + { + rgb_mode = 2; + } + + // mode 3: 10 7 7 6 + if (b < 8192 && c < 8192 && d < 2048) + { + rgb_mode = 3; + } + + // mode 4: 11 8 6 5 + if (b < 8192 && c < 2048 && d < 512) + { + rgb_mode = 4; + } + + // mode 5: 11 6 8 6 + if (b < 2048 && c < 8192 && d < 1024) + { + rgb_mode = 5; + } + + // mode 6: 12 7 7 5 + if (b < 2048 && c < 2048 && d < 256) + { + rgb_mode = 6; + } + + // mode 7: 12 6 7 6 + if (b < 1024 && c < 2048 && d < 512) + { + rgb_mode = 7; + } + + static const float rgbo_error_scales[6] { 4.0f, 4.0f, 16.0f, 64.0f, 256.0f, 1024.0f }; + static const float rgb_error_scales[9] { 64.0f, 64.0f, 16.0f, 16.0f, 4.0f, 4.0f, 1.0f, 1.0f, 384.0f }; + + float mode7mult = rgbo_error_scales[rgbo_mode] * 0.0015f; // Empirically determined .... + float mode11mult = rgb_error_scales[rgb_mode] * 0.010f; // Empirically determined .... + + + float lum_high = hadd_rgb_s(ep1) * (1.0f / 3.0f); + float lum_low = hadd_rgb_s(ep0) * (1.0f / 3.0f); + float lumdif = lum_high - lum_low; + float mode23mult = lumdif < 960 ? 4.0f : lumdif < 3968 ? 16.0f : 128.0f; + + mode23mult *= 0.0005f; // Empirically determined .... + + // Pick among the available HDR endpoint modes + for (int i = QUANT_2; i < QUANT_16; i++) + { + best_error[i][3] = ERROR_CALC_DEFAULT; + best_error[i][2] = ERROR_CALC_DEFAULT; + best_error[i][1] = ERROR_CALC_DEFAULT; + best_error[i][0] = ERROR_CALC_DEFAULT; + + format_of_choice[i][3] = static_cast<uint8_t>(encode_hdr_alpha ? FMT_HDR_RGBA : FMT_HDR_RGB_LDR_ALPHA); + format_of_choice[i][2] = FMT_HDR_RGB; + format_of_choice[i][1] = FMT_HDR_RGB_SCALE; + format_of_choice[i][0] = FMT_HDR_LUMINANCE_LARGE_RANGE; + } + + for (int i = QUANT_16; i <= QUANT_256; i++) + { + // The base_quant_error should depend on the scale-factor that would be used during + // actual encode of the color value + + float base_quant_error = baseline_quant_error[i - QUANT_6] * static_cast<float>(partition_size); + float rgb_quantization_error = error_weight_rgbsum * base_quant_error * 2.0f; + float alpha_quantization_error = error_weight.lane<3>() * base_quant_error * 2.0f; + float rgba_quantization_error = rgb_quantization_error + alpha_quantization_error; + + // For 8 integers, we have two encodings: one with HDR A and another one with LDR A + + float full_hdr_rgba_error = rgba_quantization_error + rgb_range_error + alpha_range_error; + best_error[i][3] = full_hdr_rgba_error; + format_of_choice[i][3] = static_cast<uint8_t>(encode_hdr_alpha ? FMT_HDR_RGBA : FMT_HDR_RGB_LDR_ALPHA); + + // For 6 integers, we have one HDR-RGB encoding + float full_hdr_rgb_error = (rgb_quantization_error * mode11mult) + rgb_range_error + eci.alpha_drop_error; + best_error[i][2] = full_hdr_rgb_error; + format_of_choice[i][2] = FMT_HDR_RGB; + + // For 4 integers, we have one HDR-RGB-Scale encoding + float hdr_rgb_scale_error = (rgb_quantization_error * mode7mult) + rgb_range_error + eci.alpha_drop_error + eci.rgb_luma_error; + + best_error[i][1] = hdr_rgb_scale_error; + format_of_choice[i][1] = FMT_HDR_RGB_SCALE; + + // For 2 integers, we assume luminance-with-large-range + float hdr_luminance_error = (rgb_quantization_error * mode23mult) + rgb_range_error + eci.alpha_drop_error + eci.luminance_error; + best_error[i][0] = hdr_luminance_error; + format_of_choice[i][0] = FMT_HDR_LUMINANCE_LARGE_RANGE; + } + } + else + { + for (int i = QUANT_2; i < QUANT_6; i++) + { + best_error[i][3] = ERROR_CALC_DEFAULT; + best_error[i][2] = ERROR_CALC_DEFAULT; + best_error[i][1] = ERROR_CALC_DEFAULT; + best_error[i][0] = ERROR_CALC_DEFAULT; + + format_of_choice[i][3] = FMT_RGBA; + format_of_choice[i][2] = FMT_RGB; + format_of_choice[i][1] = FMT_RGB_SCALE; + format_of_choice[i][0] = FMT_LUMINANCE; + } + + float base_quant_error_rgb = error_weight_rgbsum * static_cast<float>(partition_size); + float base_quant_error_a = error_weight.lane<3>() * static_cast<float>(partition_size); + float base_quant_error_rgba = base_quant_error_rgb + base_quant_error_a; + + float error_scale_bc_rgba = eci.can_blue_contract ? 0.625f : 1.0f; + float error_scale_oe_rgba = eci.can_offset_encode ? 0.5f : 1.0f; + + float error_scale_bc_rgb = eci.can_blue_contract ? 0.5f : 1.0f; + float error_scale_oe_rgb = eci.can_offset_encode ? 0.25f : 1.0f; + + // Pick among the available LDR endpoint modes + for (int i = QUANT_6; i <= QUANT_256; i++) + { + // Offset encoding not possible at higher quant levels + if (i >= QUANT_192) + { + error_scale_oe_rgba = 1.0f; + error_scale_oe_rgb = 1.0f; + } + + float base_quant_error = baseline_quant_error[i - QUANT_6]; + float quant_error_rgb = base_quant_error_rgb * base_quant_error; + float quant_error_rgba = base_quant_error_rgba * base_quant_error; + + // 8 integers can encode as RGBA+RGBA + float full_ldr_rgba_error = quant_error_rgba + * error_scale_bc_rgba + * error_scale_oe_rgba + + rgb_range_error + + alpha_range_error; + + best_error[i][3] = full_ldr_rgba_error; + format_of_choice[i][3] = FMT_RGBA; + + // 6 integers can encode as RGB+RGB or RGBS+AA + float full_ldr_rgb_error = quant_error_rgb + * error_scale_bc_rgb + * error_scale_oe_rgb + + rgb_range_error + + eci.alpha_drop_error; + + float rgbs_alpha_error = quant_error_rgba + + eci.rgb_scale_error + + rgb_range_error + + alpha_range_error; + + if (rgbs_alpha_error < full_ldr_rgb_error) + { + best_error[i][2] = rgbs_alpha_error; + format_of_choice[i][2] = FMT_RGB_SCALE_ALPHA; + } + else + { + best_error[i][2] = full_ldr_rgb_error; + format_of_choice[i][2] = FMT_RGB; + } + + // 4 integers can encode as RGBS or LA+LA + float ldr_rgbs_error = quant_error_rgb + + rgb_range_error + + eci.alpha_drop_error + + eci.rgb_scale_error; + + float lum_alpha_error = quant_error_rgba + + rgb_range_error + + alpha_range_error + + eci.luminance_error; + + if (ldr_rgbs_error < lum_alpha_error) + { + best_error[i][1] = ldr_rgbs_error; + format_of_choice[i][1] = FMT_RGB_SCALE; + } + else + { + best_error[i][1] = lum_alpha_error; + format_of_choice[i][1] = FMT_LUMINANCE_ALPHA; + } + + // 2 integers can encode as L+L + float luminance_error = quant_error_rgb + + rgb_range_error + + eci.alpha_drop_error + + eci.luminance_error; + + best_error[i][0] = luminance_error; + format_of_choice[i][0] = FMT_LUMINANCE; + } + } +} + +/** + * @brief For one partition compute the best format and quantization for a given bit count. + * + * @param best_combined_error The best error for each quant level and integer count. + * @param best_combined_format The best format for each quant level and integer count. + * @param bits_available The number of bits available for encoding. + * @param[out] best_quant_level The output best color quant level. + * @param[out] best_format The output best color format. + * + * @return The output error for the best pairing. + */ +static float one_partition_find_best_combination_for_bitcount( + const float best_combined_error[21][4], + const uint8_t best_combined_format[21][4], + int bits_available, + uint8_t& best_quant_level, + uint8_t& best_format +) { + int best_integer_count = 0; + float best_integer_count_error = ERROR_CALC_DEFAULT; + + for (int integer_count = 1; integer_count <= 4; integer_count++) + { + // Compute the quantization level for a given number of integers and a given number of bits + int quant_level = quant_mode_table[integer_count][bits_available]; + + // Don't have enough bits to represent a given endpoint format at all! + if (quant_level < QUANT_6) + { + continue; + } + + float integer_count_error = best_combined_error[quant_level][integer_count - 1]; + if (integer_count_error < best_integer_count_error) + { + best_integer_count_error = integer_count_error; + best_integer_count = integer_count - 1; + } + } + + int ql = quant_mode_table[best_integer_count + 1][bits_available]; + + best_quant_level = static_cast<uint8_t>(ql); + best_format = FMT_LUMINANCE; + + if (ql >= QUANT_6) + { + best_format = best_combined_format[ql][best_integer_count]; + } + + return best_integer_count_error; +} + +/** + * @brief For 2 partitions compute the best format combinations for every pair of quant mode and integer count. + * + * @param best_error The best error for a single endpoint quant level and integer count. + * @param best_format The best format for a single endpoint quant level and integer count. + * @param[out] best_combined_error The best combined error pairings for the 2 partitions. + * @param[out] best_combined_format The best combined format pairings for the 2 partitions. + */ +static void two_partitions_find_best_combination_for_every_quantization_and_integer_count( + const float best_error[2][21][4], // indexed by (partition, quant-level, integer-pair-count-minus-1) + const uint8_t best_format[2][21][4], + float best_combined_error[21][7], // indexed by (quant-level, integer-pair-count-minus-2) + uint8_t best_combined_format[21][7][2] +) { + for (int i = QUANT_2; i <= QUANT_256; i++) + { + for (int j = 0; j < 7; j++) + { + best_combined_error[i][j] = ERROR_CALC_DEFAULT; + } + } + + for (int quant = QUANT_6; quant <= QUANT_256; quant++) + { + for (int i = 0; i < 4; i++) // integer-count for first endpoint-pair + { + for (int j = 0; j < 4; j++) // integer-count for second endpoint-pair + { + int low2 = astc::min(i, j); + int high2 = astc::max(i, j); + if ((high2 - low2) > 1) + { + continue; + } + + int intcnt = i + j; + float errorterm = astc::min(best_error[0][quant][i] + best_error[1][quant][j], 1e10f); + if (errorterm <= best_combined_error[quant][intcnt]) + { + best_combined_error[quant][intcnt] = errorterm; + best_combined_format[quant][intcnt][0] = best_format[0][quant][i]; + best_combined_format[quant][intcnt][1] = best_format[1][quant][j]; + } + } + } + } +} + +/** + * @brief For 2 partitions compute the best format and quantization for a given bit count. + * + * @param best_combined_error The best error for each quant level and integer count. + * @param best_combined_format The best format for each quant level and integer count. + * @param bits_available The number of bits available for encoding. + * @param[out] best_quant_level The output best color quant level. + * @param[out] best_quant_level_mod The output best color quant level assuming two more bits are available. + * @param[out] best_formats The output best color formats. + * + * @return The output error for the best pairing. + */ +static float two_partitions_find_best_combination_for_bitcount( + float best_combined_error[21][7], + uint8_t best_combined_format[21][7][2], + int bits_available, + uint8_t& best_quant_level, + uint8_t& best_quant_level_mod, + uint8_t* best_formats +) { + int best_integer_count = 0; + float best_integer_count_error = ERROR_CALC_DEFAULT; + + for (int integer_count = 2; integer_count <= 8; integer_count++) + { + // Compute the quantization level for a given number of integers and a given number of bits + int quant_level = quant_mode_table[integer_count][bits_available]; + + // Don't have enough bits to represent a given endpoint format at all! + if (quant_level < QUANT_6) + { + break; + } + + float integer_count_error = best_combined_error[quant_level][integer_count - 2]; + if (integer_count_error < best_integer_count_error) + { + best_integer_count_error = integer_count_error; + best_integer_count = integer_count; + } + } + + int ql = quant_mode_table[best_integer_count][bits_available]; + int ql_mod = quant_mode_table[best_integer_count][bits_available + 2]; + + best_quant_level = static_cast<uint8_t>(ql); + best_quant_level_mod = static_cast<uint8_t>(ql_mod); + + if (ql >= QUANT_6) + { + for (int i = 0; i < 2; i++) + { + best_formats[i] = best_combined_format[ql][best_integer_count - 2][i]; + } + } + else + { + for (int i = 0; i < 2; i++) + { + best_formats[i] = FMT_LUMINANCE; + } + } + + return best_integer_count_error; +} + +/** + * @brief For 3 partitions compute the best format combinations for every pair of quant mode and integer count. + * + * @param best_error The best error for a single endpoint quant level and integer count. + * @param best_format The best format for a single endpoint quant level and integer count. + * @param[out] best_combined_error The best combined error pairings for the 3 partitions. + * @param[out] best_combined_format The best combined format pairings for the 3 partitions. + */ +static void three_partitions_find_best_combination_for_every_quantization_and_integer_count( + const float best_error[3][21][4], // indexed by (partition, quant-level, integer-count) + const uint8_t best_format[3][21][4], + float best_combined_error[21][10], + uint8_t best_combined_format[21][10][3] +) { + for (int i = QUANT_2; i <= QUANT_256; i++) + { + for (int j = 0; j < 10; j++) + { + best_combined_error[i][j] = ERROR_CALC_DEFAULT; + } + } + + for (int quant = QUANT_6; quant <= QUANT_256; quant++) + { + for (int i = 0; i < 4; i++) // integer-count for first endpoint-pair + { + for (int j = 0; j < 4; j++) // integer-count for second endpoint-pair + { + int low2 = astc::min(i, j); + int high2 = astc::max(i, j); + if ((high2 - low2) > 1) + { + continue; + } + + for (int k = 0; k < 4; k++) // integer-count for third endpoint-pair + { + int low3 = astc::min(k, low2); + int high3 = astc::max(k, high2); + if ((high3 - low3) > 1) + { + continue; + } + + int intcnt = i + j + k; + float errorterm = astc::min(best_error[0][quant][i] + best_error[1][quant][j] + best_error[2][quant][k], 1e10f); + if (errorterm <= best_combined_error[quant][intcnt]) + { + best_combined_error[quant][intcnt] = errorterm; + best_combined_format[quant][intcnt][0] = best_format[0][quant][i]; + best_combined_format[quant][intcnt][1] = best_format[1][quant][j]; + best_combined_format[quant][intcnt][2] = best_format[2][quant][k]; + } + } + } + } + } +} + +/** + * @brief For 3 partitions compute the best format and quantization for a given bit count. + * + * @param best_combined_error The best error for each quant level and integer count. + * @param best_combined_format The best format for each quant level and integer count. + * @param bits_available The number of bits available for encoding. + * @param[out] best_quant_level The output best color quant level. + * @param[out] best_quant_level_mod The output best color quant level assuming two more bits are available. + * @param[out] best_formats The output best color formats. + * + * @return The output error for the best pairing. + */ +static float three_partitions_find_best_combination_for_bitcount( + const float best_combined_error[21][10], + const uint8_t best_combined_format[21][10][3], + int bits_available, + uint8_t& best_quant_level, + uint8_t& best_quant_level_mod, + uint8_t* best_formats +) { + int best_integer_count = 0; + float best_integer_count_error = ERROR_CALC_DEFAULT; + + for (int integer_count = 3; integer_count <= 9; integer_count++) + { + // Compute the quantization level for a given number of integers and a given number of bits + int quant_level = quant_mode_table[integer_count][bits_available]; + + // Don't have enough bits to represent a given endpoint format at all! + if (quant_level < QUANT_6) + { + break; + } + + float integer_count_error = best_combined_error[quant_level][integer_count - 3]; + if (integer_count_error < best_integer_count_error) + { + best_integer_count_error = integer_count_error; + best_integer_count = integer_count; + } + } + + int ql = quant_mode_table[best_integer_count][bits_available]; + int ql_mod = quant_mode_table[best_integer_count][bits_available + 5]; + + best_quant_level = static_cast<uint8_t>(ql); + best_quant_level_mod = static_cast<uint8_t>(ql_mod); + + if (ql >= QUANT_6) + { + for (int i = 0; i < 3; i++) + { + best_formats[i] = best_combined_format[ql][best_integer_count - 3][i]; + } + } + else + { + for (int i = 0; i < 3; i++) + { + best_formats[i] = FMT_LUMINANCE; + } + } + + return best_integer_count_error; +} + +/** + * @brief For 4 partitions compute the best format combinations for every pair of quant mode and integer count. + * + * @param best_error The best error for a single endpoint quant level and integer count. + * @param best_format The best format for a single endpoint quant level and integer count. + * @param[out] best_combined_error The best combined error pairings for the 4 partitions. + * @param[out] best_combined_format The best combined format pairings for the 4 partitions. + */ +static void four_partitions_find_best_combination_for_every_quantization_and_integer_count( + const float best_error[4][21][4], // indexed by (partition, quant-level, integer-count) + const uint8_t best_format[4][21][4], + float best_combined_error[21][13], + uint8_t best_combined_format[21][13][4] +) { + for (int i = QUANT_2; i <= QUANT_256; i++) + { + for (int j = 0; j < 13; j++) + { + best_combined_error[i][j] = ERROR_CALC_DEFAULT; + } + } + + for (int quant = QUANT_6; quant <= QUANT_256; quant++) + { + for (int i = 0; i < 4; i++) // integer-count for first endpoint-pair + { + for (int j = 0; j < 4; j++) // integer-count for second endpoint-pair + { + int low2 = astc::min(i, j); + int high2 = astc::max(i, j); + if ((high2 - low2) > 1) + { + continue; + } + + for (int k = 0; k < 4; k++) // integer-count for third endpoint-pair + { + int low3 = astc::min(k, low2); + int high3 = astc::max(k, high2); + if ((high3 - low3) > 1) + { + continue; + } + + for (int l = 0; l < 4; l++) // integer-count for fourth endpoint-pair + { + int low4 = astc::min(l, low3); + int high4 = astc::max(l, high3); + if ((high4 - low4) > 1) + { + continue; + } + + int intcnt = i + j + k + l; + float errorterm = astc::min(best_error[0][quant][i] + best_error[1][quant][j] + best_error[2][quant][k] + best_error[3][quant][l], 1e10f); + if (errorterm <= best_combined_error[quant][intcnt]) + { + best_combined_error[quant][intcnt] = errorterm; + best_combined_format[quant][intcnt][0] = best_format[0][quant][i]; + best_combined_format[quant][intcnt][1] = best_format[1][quant][j]; + best_combined_format[quant][intcnt][2] = best_format[2][quant][k]; + best_combined_format[quant][intcnt][3] = best_format[3][quant][l]; + } + } + } + } + } + } +} + +/** + * @brief For 4 partitions compute the best format and quantization for a given bit count. + * + * @param best_combined_error The best error for each quant level and integer count. + * @param best_combined_format The best format for each quant level and integer count. + * @param bits_available The number of bits available for encoding. + * @param[out] best_quant_level The output best color quant level. + * @param[out] best_quant_level_mod The output best color quant level assuming two more bits are available. + * @param[out] best_formats The output best color formats. + * + * @return best_error The output error for the best pairing. + */ +static float four_partitions_find_best_combination_for_bitcount( + const float best_combined_error[21][13], + const uint8_t best_combined_format[21][13][4], + int bits_available, + uint8_t& best_quant_level, + uint8_t& best_quant_level_mod, + uint8_t* best_formats +) { + int best_integer_count = 0; + float best_integer_count_error = ERROR_CALC_DEFAULT; + + for (int integer_count = 4; integer_count <= 9; integer_count++) + { + // Compute the quantization level for a given number of integers and a given number of bits + int quant_level = quant_mode_table[integer_count][bits_available]; + + // Don't have enough bits to represent a given endpoint format at all! + if (quant_level < QUANT_6) + { + break; + } + + float integer_count_error = best_combined_error[quant_level][integer_count - 4]; + if (integer_count_error < best_integer_count_error) + { + best_integer_count_error = integer_count_error; + best_integer_count = integer_count; + } + } + + int ql = quant_mode_table[best_integer_count][bits_available]; + int ql_mod = quant_mode_table[best_integer_count][bits_available + 8]; + + best_quant_level = static_cast<uint8_t>(ql); + best_quant_level_mod = static_cast<uint8_t>(ql_mod); + + if (ql >= QUANT_6) + { + for (int i = 0; i < 4; i++) + { + best_formats[i] = best_combined_format[ql][best_integer_count - 4][i]; + } + } + else + { + for (int i = 0; i < 4; i++) + { + best_formats[i] = FMT_LUMINANCE; + } + } + + return best_integer_count_error; +} + +/* See header for documentation. */ +unsigned int compute_ideal_endpoint_formats( + const partition_info& pi, + const image_block& blk, + const endpoints& ep, + // bitcounts and errors computed for the various quantization methods + const int8_t* qwt_bitcounts, + const float* qwt_errors, + unsigned int tune_candidate_limit, + unsigned int start_block_mode, + unsigned int end_block_mode, + // output data + uint8_t partition_format_specifiers[TUNE_MAX_TRIAL_CANDIDATES][BLOCK_MAX_PARTITIONS], + int block_mode[TUNE_MAX_TRIAL_CANDIDATES], + quant_method quant_level[TUNE_MAX_TRIAL_CANDIDATES], + quant_method quant_level_mod[TUNE_MAX_TRIAL_CANDIDATES], + compression_working_buffers& tmpbuf +) { + int partition_count = pi.partition_count; + + promise(partition_count > 0); + + bool encode_hdr_rgb = static_cast<bool>(blk.rgb_lns[0]); + bool encode_hdr_alpha = static_cast<bool>(blk.alpha_lns[0]); + + // Compute the errors that result from various encoding choices (such as using luminance instead + // of RGB, discarding Alpha, using RGB-scale in place of two separate RGB endpoints and so on) + encoding_choice_errors eci[BLOCK_MAX_PARTITIONS]; + compute_encoding_choice_errors(blk, pi, ep, eci); + + float best_error[BLOCK_MAX_PARTITIONS][21][4]; + uint8_t format_of_choice[BLOCK_MAX_PARTITIONS][21][4]; + for (int i = 0; i < partition_count; i++) + { + compute_color_error_for_every_integer_count_and_quant_level( + encode_hdr_rgb, encode_hdr_alpha, i, + pi, eci[i], ep, blk.channel_weight, best_error[i], + format_of_choice[i]); + } + + float* errors_of_best_combination = tmpbuf.errors_of_best_combination; + uint8_t* best_quant_levels = tmpbuf.best_quant_levels; + uint8_t* best_quant_levels_mod = tmpbuf.best_quant_levels_mod; + uint8_t (&best_ep_formats)[WEIGHTS_MAX_BLOCK_MODES][BLOCK_MAX_PARTITIONS] = tmpbuf.best_ep_formats; + + // Ensure that the first iteration understep contains data that will never be picked + vfloat clear_error(ERROR_CALC_DEFAULT); + vint clear_quant(0); + + unsigned int packed_start_block_mode = round_down_to_simd_multiple_vla(start_block_mode); + storea(clear_error, errors_of_best_combination + packed_start_block_mode); + store_nbytes(clear_quant, best_quant_levels + packed_start_block_mode); + store_nbytes(clear_quant, best_quant_levels_mod + packed_start_block_mode); + + // Ensure that last iteration overstep contains data that will never be picked + unsigned int packed_end_block_mode = round_down_to_simd_multiple_vla(end_block_mode - 1); + storea(clear_error, errors_of_best_combination + packed_end_block_mode); + store_nbytes(clear_quant, best_quant_levels + packed_end_block_mode); + store_nbytes(clear_quant, best_quant_levels_mod + packed_end_block_mode); + + // Track a scalar best to avoid expensive search at least once ... + float error_of_best_combination = ERROR_CALC_DEFAULT; + int index_of_best_combination = -1; + + // The block contains 1 partition + if (partition_count == 1) + { + for (unsigned int i = start_block_mode; i < end_block_mode; i++) + { + if (qwt_errors[i] >= ERROR_CALC_DEFAULT) + { + errors_of_best_combination[i] = ERROR_CALC_DEFAULT; + continue; + } + + float error_of_best = one_partition_find_best_combination_for_bitcount( + best_error[0], format_of_choice[0], qwt_bitcounts[i], + best_quant_levels[i], best_ep_formats[i][0]); + + float total_error = error_of_best + qwt_errors[i]; + errors_of_best_combination[i] = total_error; + best_quant_levels_mod[i] = best_quant_levels[i]; + + if (total_error < error_of_best_combination) + { + error_of_best_combination = total_error; + index_of_best_combination = i; + } + } + } + // The block contains 2 partitions + else if (partition_count == 2) + { + float combined_best_error[21][7]; + uint8_t formats_of_choice[21][7][2]; + + two_partitions_find_best_combination_for_every_quantization_and_integer_count( + best_error, format_of_choice, combined_best_error, formats_of_choice); + + assert(start_block_mode == 0); + for (unsigned int i = 0; i < end_block_mode; i++) + { + if (qwt_errors[i] >= ERROR_CALC_DEFAULT) + { + errors_of_best_combination[i] = ERROR_CALC_DEFAULT; + continue; + } + + float error_of_best = two_partitions_find_best_combination_for_bitcount( + combined_best_error, formats_of_choice, qwt_bitcounts[i], + best_quant_levels[i], best_quant_levels_mod[i], + best_ep_formats[i]); + + float total_error = error_of_best + qwt_errors[i]; + errors_of_best_combination[i] = total_error; + + if (total_error < error_of_best_combination) + { + error_of_best_combination = total_error; + index_of_best_combination = i; + } + } + } + // The block contains 3 partitions + else if (partition_count == 3) + { + float combined_best_error[21][10]; + uint8_t formats_of_choice[21][10][3]; + + three_partitions_find_best_combination_for_every_quantization_and_integer_count( + best_error, format_of_choice, combined_best_error, formats_of_choice); + + assert(start_block_mode == 0); + for (unsigned int i = 0; i < end_block_mode; i++) + { + if (qwt_errors[i] >= ERROR_CALC_DEFAULT) + { + errors_of_best_combination[i] = ERROR_CALC_DEFAULT; + continue; + } + + float error_of_best = three_partitions_find_best_combination_for_bitcount( + combined_best_error, formats_of_choice, qwt_bitcounts[i], + best_quant_levels[i], best_quant_levels_mod[i], + best_ep_formats[i]); + + float total_error = error_of_best + qwt_errors[i]; + errors_of_best_combination[i] = total_error; + + if (total_error < error_of_best_combination) + { + error_of_best_combination = total_error; + index_of_best_combination = i; + } + } + } + // The block contains 4 partitions + else // if (partition_count == 4) + { + assert(partition_count == 4); + float combined_best_error[21][13]; + uint8_t formats_of_choice[21][13][4]; + + four_partitions_find_best_combination_for_every_quantization_and_integer_count( + best_error, format_of_choice, combined_best_error, formats_of_choice); + + assert(start_block_mode == 0); + for (unsigned int i = 0; i < end_block_mode; i++) + { + if (qwt_errors[i] >= ERROR_CALC_DEFAULT) + { + errors_of_best_combination[i] = ERROR_CALC_DEFAULT; + continue; + } + + float error_of_best = four_partitions_find_best_combination_for_bitcount( + combined_best_error, formats_of_choice, qwt_bitcounts[i], + best_quant_levels[i], best_quant_levels_mod[i], + best_ep_formats[i]); + + float total_error = error_of_best + qwt_errors[i]; + errors_of_best_combination[i] = total_error; + + if (total_error < error_of_best_combination) + { + error_of_best_combination = total_error; + index_of_best_combination = i; + } + } + } + + int best_error_weights[TUNE_MAX_TRIAL_CANDIDATES]; + + // Fast path the first result and avoid the list search for trial 0 + best_error_weights[0] = index_of_best_combination; + if (index_of_best_combination >= 0) + { + errors_of_best_combination[index_of_best_combination] = ERROR_CALC_DEFAULT; + } + + // Search the remaining results and pick the best candidate modes for trial 1+ + for (unsigned int i = 1; i < tune_candidate_limit; i++) + { + vint vbest_error_index(-1); + vfloat vbest_ep_error(ERROR_CALC_DEFAULT); + + start_block_mode = round_down_to_simd_multiple_vla(start_block_mode); + vint lane_ids = vint::lane_id() + vint(start_block_mode); + for (unsigned int j = start_block_mode; j < end_block_mode; j += ASTCENC_SIMD_WIDTH) + { + vfloat err = vfloat(errors_of_best_combination + j); + vmask mask = err < vbest_ep_error; + vbest_ep_error = select(vbest_ep_error, err, mask); + vbest_error_index = select(vbest_error_index, lane_ids, mask); + lane_ids += vint(ASTCENC_SIMD_WIDTH); + } + + // Pick best mode from the SIMD result, using lowest matching index to ensure invariance + vmask lanes_min_error = vbest_ep_error == hmin(vbest_ep_error); + vbest_error_index = select(vint(0x7FFFFFFF), vbest_error_index, lanes_min_error); + vbest_error_index = hmin(vbest_error_index); + int best_error_index = vbest_error_index.lane<0>(); + + best_error_weights[i] = best_error_index; + + // Max the error for this candidate so we don't pick it again + if (best_error_index >= 0) + { + errors_of_best_combination[best_error_index] = ERROR_CALC_DEFAULT; + } + // Early-out if no more candidates are valid + else + { + break; + } + } + + for (unsigned int i = 0; i < tune_candidate_limit; i++) + { + if (best_error_weights[i] < 0) + { + return i; + } + + block_mode[i] = best_error_weights[i]; + + quant_level[i] = static_cast<quant_method>(best_quant_levels[best_error_weights[i]]); + quant_level_mod[i] = static_cast<quant_method>(best_quant_levels_mod[best_error_weights[i]]); + + assert(quant_level[i] >= QUANT_6 && quant_level[i] <= QUANT_256); + assert(quant_level_mod[i] >= QUANT_6 && quant_level_mod[i] <= QUANT_256); + + for (int j = 0; j < partition_count; j++) + { + partition_format_specifiers[i][j] = best_ep_formats[best_error_weights[i]][j]; + } + } + + return tune_candidate_limit; +} + +#endif |