private long OneStatPass(int width, int height, int yStride, int uvStride, Vp8RdLevel rdOpt, int nbMbs, PassStats stats)
{
Span <byte> y = this.Y.GetSpan();
Span <byte> u = this.U.GetSpan();
Span <byte> v = this.V.GetSpan();
var it = new Vp8EncIterator(this.YTop, this.UvTop, this.Nz, this.MbInfo, this.Preds, this.TopDerr, this.Mbw, this.Mbh);
long size = 0;
long sizeP0 = 0;
long distortion = 0;
long pixelCount = nbMbs * 384;
it.Init();
this.SetLoopParams(stats.Q);
var info = new Vp8ModeScore();
do
{
info.Clear();
it.Import(y, u, v, yStride, uvStride, width, height, false);
if (this.Decimate(it, ref info, rdOpt))
{
// Just record the number of skips and act like skipProba is not used.
++this.Proba.NbSkip;
}
this.RecordResiduals(it, info);
size += info.R + info.H;
sizeP0 += info.H;
distortion += info.D;
it.SaveBoundary();
}while (it.Next() && --nbMbs > 0);
sizeP0 += this.SegmentHeader.Size;
if (stats.DoSizeSearch)
{
size += this.Proba.FinalizeSkipProba(this.Mbw, this.Mbh);
size += this.Proba.FinalizeTokenProbas();
size = ((size + sizeP0 + 1024) >> 11) + HeaderSizeEstimate;
stats.Value = size;
}
else
{
stats.Value = GetPsnr(distortion, pixelCount);
}
return(sizeP0);
}
/// <summary>
/// Only collect statistics(number of skips, token usage, ...).
/// This is used for deciding optimal probabilities. It also modifies the
/// quantizer value if some target (size, PSNR) was specified.
/// </summary>
private void StatLoop(int width, int height, int yStride, int uvStride)
{
int targetSize = 0; // TODO: target size is hardcoded.
float targetPsnr = 0.0f; // TODO: targetPsnr is hardcoded.
bool doSearch = targetSize > 0 || targetPsnr > 0;
bool fastProbe = (this.method == 0 || this.method == WebpEncodingMethod.Level3) && !doSearch;
int numPassLeft = this.entropyPasses;
Vp8RdLevel rdOpt = this.method >= WebpEncodingMethod.Level3 || doSearch ? Vp8RdLevel.RdOptBasic : Vp8RdLevel.RdOptNone;
int nbMbs = this.Mbw * this.Mbh;
var stats = new PassStats(targetSize, targetPsnr, QMin, QMax, this.quality);
this.Proba.ResetTokenStats();
// Fast mode: quick analysis pass over few mbs. Better than nothing.
if (fastProbe)
{
if (this.method == WebpEncodingMethod.Level3)
{
// We need more stats for method 3 to be reliable.
nbMbs = nbMbs > 200 ? nbMbs >> 1 : 100;
}
else
{
nbMbs = nbMbs > 200 ? nbMbs >> 2 : 50;
}
}
while (numPassLeft-- > 0)
{
bool isLastPass = (MathF.Abs(stats.Dq) <= DqLimit) || (numPassLeft == 0) || (this.maxI4HeaderBits == 0);
long sizeP0 = this.OneStatPass(width, height, yStride, uvStride, rdOpt, nbMbs, stats);
if (sizeP0 == 0)
{
return;
}
if (this.maxI4HeaderBits > 0 && sizeP0 > (long)Partition0SizeLimit)
{
++numPassLeft;
this.maxI4HeaderBits >>= 1; // strengthen header bit limitation...
continue; // ...and start over
}
if (isLastPass)
{
break;
}
// If no target size: just do several pass without changing 'q'
if (doSearch)
{
stats.ComputeNextQ();
if (MathF.Abs(stats.Dq) <= DqLimit)
{
break;
}
}
}
if (!doSearch || !stats.DoSizeSearch)
{
// Need to finalize probas now, since it wasn't done during the search.
this.Proba.FinalizeSkipProba(this.Mbw, this.Mbh);
this.Proba.FinalizeTokenProbas();
}
// Finalize costs.
this.Proba.CalculateLevelCosts();
}