[x265] [PATCH] Add vbv-end tolerance check

[Alex Giladi]

Does this "5% tolerance" imply that CPB fullness as defined by vbv-end can
be exceeded by 5%?

On Fri, Jun 8, 2018 at 6:39 AM, <aruna at multicorewareinc.com> wrote:

> # HG changeset patch
> # User Aruna Matheswaran <aruna at multicorewareinc.com>
> # Date 1523005500 -19800
> #      Fri Apr 06 14:35:00 2018 +0530
> # Node ID ed853c4af6710a991d0cdf4bf68e00fe32edaacb
> # Parent  182914e1d201395d152e310db7f5cf29ab3c787e
> Add vbv-end tolerance check
>
> This will attempt to keep the desired fraction of the target buffer (
> specified
> by vbv-end ) empty within a defined error margin of 5%.
>
> diff -r 182914e1d201 -r ed853c4af671 source/encoder/ratecontrol.cpp
> --- a/source/encoder/ratecontrol.cpp    Wed Mar 14 12:30:28 2018 +0530
> +++ b/source/encoder/ratecontrol.cpp    Fri Apr 06 14:35:00 2018 +0530
> @@ -1282,6 +1282,12 @@
>          m_predictedBits = m_totalBits;
>          updateVbvPlan(enc);
>          rce->bufferFill = m_bufferFill;
> +        rce->vbvEndAdj = false;
> +        if (m_param->vbvBufferEnd && rce->encodeOrder >=
> m_param->vbvEndFrameAdjust * m_param->totalFrames)
> +        {
> +            rce->vbvEndAdj = true;
> +            rce->targetFill = 0;
> +        }
>
>          int mincr = enc->m_vps.ptl.minCrForLevel;
>          /* Profiles above Main10 don't require maxAU size check, so just
> set the maximum to a large value. */
> @@ -2173,12 +2179,12 @@
>                      curBits = predictSize(&m_pred[predType],
> frameQ[type], (double)satd);
>                      bufferFillCur -= curBits;
>                  }
> -                if (m_param->vbvBufferEnd && rce->encodeOrder >=
> m_param->vbvEndFrameAdjust * m_param->totalFrames)
> +                if (rce->vbvEndAdj)
>                  {
>                      bool loopBreak = false;
>                      double bufferDiff = m_param->vbvBufferEnd -
> (m_bufferFill / m_bufferSize);
> -                    targetFill = m_bufferFill + m_bufferSize *
> (bufferDiff / (m_param->totalFrames - rce->encodeOrder));
> -                    if (bufferFillCur < targetFill)
> +                    rce->targetFill = m_bufferFill + m_bufferSize *
> (bufferDiff / (m_param->totalFrames - rce->encodeOrder));
> +                    if (bufferFillCur < rce->targetFill)
>                      {
>                          q *= 1.01;
>                          loopTerminate |= 1;
> @@ -2421,6 +2427,7 @@
>          double rcTol = bufferLeftPlanned / m_param->frameNumThreads *
> m_rateTolerance;
>          int32_t encodedBitsSoFar = 0;
>          double accFrameBits = predictRowsSizeSum(curFrame, rce, qpVbv,
> encodedBitsSoFar);
> +        double vbvEndBias = 0.95;
>
>          /* * Don't increase the row QPs until a sufficent amount of the
> bits of
>           * the frame have been processed, in case a flat area at the top
> of the
> @@ -2442,7 +2449,8 @@
>          while (qpVbv < qpMax
>                 && (((accFrameBits > rce->frameSizePlanned + rcTol) ||
>                     (rce->bufferFill - accFrameBits < bufferLeftPlanned *
> 0.5) ||
> -                   (accFrameBits > rce->frameSizePlanned && qpVbv <
> rce->qpNoVbv))
> +                   (accFrameBits > rce->frameSizePlanned && qpVbv <
> rce->qpNoVbv) ||
> +                   (rce->vbvEndAdj && ((rce->bufferFill - accFrameBits) <
> (rce->targetFill * vbvEndBias))))
>                     && (!m_param->rc.bStrictCbr ? 1 : abrOvershoot > 0.1)))
>          {
>              qpVbv += stepSize;
> @@ -2453,7 +2461,8 @@
>          while (qpVbv > qpMin
>                 && (qpVbv > curEncData.m_rowStat[0].rowQp ||
> m_singleFrameVbv)
>                 && (((accFrameBits < rce->frameSizePlanned * 0.8f && qpVbv
> <= prevRowQp)
> -                   || accFrameBits < (rce->bufferFill - m_bufferSize +
> m_bufferRate) * 1.1)
> +                   || accFrameBits < (rce->bufferFill - m_bufferSize +
> m_bufferRate) * 1.1
> +                   || (rce->vbvEndAdj && ((rce->bufferFill -
> accFrameBits) > (rce->targetFill * vbvEndBias))))
>                     && (!m_param->rc.bStrictCbr ? 1 : abrOvershoot < 0)))
>          {
>              qpVbv -= stepSize;
> diff -r 182914e1d201 -r ed853c4af671 source/encoder/ratecontrol.h
> --- a/source/encoder/ratecontrol.h      Wed Mar 14 12:30:28 2018 +0530
> +++ b/source/encoder/ratecontrol.h      Fri Apr 06 14:35:00 2018 +0530
> @@ -82,6 +82,8 @@
>      double  rowCplxrSum;
>      double  qpNoVbv;
>      double  bufferFill;
> +    double  targetFill;
> +    bool    vbvEndAdj;
>      double  frameDuration;
>      double  clippedDuration;
>      double  frameSizeEstimated; /* hold frameSize, updated from cu level
> vbv rc */
>
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>
>
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