private const int DSCALE = 1; // storage descaling, needed to make the error fit byte public static void PickBestIntra16(Vp8EncIterator it, ref Vp8ModeScore rd, Vp8SegmentInfo[] segmentInfos, Vp8EncProba proba) { const int numBlocks = 16; Vp8SegmentInfo dqm = segmentInfos[it.CurrentMacroBlockInfo.Segment]; int lambda = dqm.LambdaI16; int tlambda = dqm.TLambda; Span <byte> src = it.YuvIn.AsSpan(Vp8EncIterator.YOffEnc); Span <int> scratch = it.Scratch3; var rdTmp = new Vp8ModeScore(); var res = new Vp8Residual(); Vp8ModeScore rdCur = rdTmp; Vp8ModeScore rdBest = rd; int mode; bool isFlat = IsFlatSource16(src); rd.ModeI16 = -1; for (mode = 0; mode < WebpConstants.NumPredModes; ++mode) { // Scratch buffer. Span <byte> tmpDst = it.YuvOut2.AsSpan(Vp8EncIterator.YOffEnc); rdCur.ModeI16 = mode; // Reconstruct. rdCur.Nz = (uint)ReconstructIntra16(it, dqm, rdCur, tmpDst, mode); // Measure RD-score. rdCur.D = LossyUtils.Vp8_Sse16X16(src, tmpDst); rdCur.SD = tlambda != 0 ? Mult8B(tlambda, LossyUtils.Vp8Disto16X16(src, tmpDst, WeightY, scratch)) : 0; rdCur.H = WebpConstants.Vp8FixedCostsI16[mode]; rdCur.R = it.GetCostLuma16(rdCur, proba, res); if (isFlat) { // Refine the first impression (which was in pixel space). isFlat = IsFlat(rdCur.YAcLevels, numBlocks, WebpConstants.FlatnessLimitI16); if (isFlat) { // Block is very flat. We put emphasis on the distortion being very low! rdCur.D *= 2; rdCur.SD *= 2; } } // Since we always examine Intra16 first, we can overwrite *rd directly. rdCur.SetRdScore(lambda); if (mode == 0 || rdCur.Score < rdBest.Score) { Vp8ModeScore tmp = rdCur; rdCur = rdBest; rdBest = tmp; it.SwapOut(); } } if (rdBest != rd) { rd = rdBest; } // Finalize score for mode decision. rd.SetRdScore(dqm.LambdaMode); it.SetIntra16Mode(rd.ModeI16); // 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.MinDisto) { dqm.StoreMaxDelta(rd.YDcLevels); } }