[x265] [PATCH 2 of 3] lambda: change chroma lambda distortion weighting to resemble x264
Deepthi Nandakumar
deepthi at multicorewareinc.com
Tue Jun 17 03:02:14 CEST 2014
Ok, thanks. The g_chromaScale table is likely constructed from the H.265
range extension spec, so I was looking in the wrong place. So, the QPs will
be reverted but the chroma lambda changes will still hold. New patch in the
works.
On Mon, Jun 16, 2014 at 8:10 PM, Aarthi Priya Thirumalai <
aarthi at multicorewareinc.com> wrote:
> pg 155 of HEVC standard:
> Table 8-9 – Specification of QpC as a function of qPi
> qPi < 30 30 31 32 33 34 35 36 37 38 39 40 41 42 43 > 43
> QpC = qPi 29 30 31 32 33 33 34 34 35 35 36 36 37 37 = qPi − 6
>
> AFAIK, values in g_chromaScale[CHROMA_420] follows the spec exactly. not
> sure how the values for other chroma formats were derived.
>
>
> On Mon, Jun 16, 2014 at 7:42 PM, Deepthi Nandakumar <
> deepthi at multicorewareinc.com> wrote:
>
>> Agreed, thats what I thought too. But the g_chromatable is not in the
>> HEVC spec at all, it's just carried over from HM.
>>
>> On Jun 16, 2014 5:38 PM, "Aarthi Priya Thirumalai" <
>> aarthi at multicorewareinc.com> wrote:
>> >
>> >
>> >
>> >
>> > On Mon, Jun 16, 2014 at 4:49 PM, <deepthi at multicorewareinc.com> wrote:
>> >>
>> >> # HG changeset patch
>> >> # User Deepthi Nandakumar <deepthi at multicorewareinc.com>
>> >> # Date 1402916716 -19800
>> >> # Mon Jun 16 16:35:16 2014 +0530
>> >> # Node ID 4d76a9c8b5abbf143e5869d55cf80a8816d99a68
>> >> # Parent ff3a85f715d43e2c21aec295426ae9dbe7c03d75
>> >> lambda: change chroma lambda distortion weighting to resemble x264.
>> >>
>> >> 1. x264 scales the chroma distortion by a factor derived from a lambda
>> offset table
>> >> when psyRd is enabled.
>> >>
>> >> 2. This patch also removes the separate Cb and Cr distortion weights
>> that were carried over from HM,
>> >> and replaces it with 256 when psy-rd is disabled, and the
>> above-mentioned lambda offset when it is enabled.
>> >>
>> >> diff -r ff3a85f715d4 -r 4d76a9c8b5ab
>> source/Lib/TLibEncoder/TEncSearch.cpp
>> >> --- a/source/Lib/TLibEncoder/TEncSearch.cpp Mon Jun 16 16:12:00
>> 2014 +0530
>> >> +++ b/source/Lib/TLibEncoder/TEncSearch.cpp Mon Jun 16 16:35:16
>> 2014 +0530
>> >> @@ -143,16 +143,22 @@
>> >> return false;
>> >> }
>> >>
>> >> -void TEncSearch::setQP(int qp, double crWeight, double cbWeight)
>> >> +void TEncSearch::setQP(int qp)
>> >> {
>> >> - double lambda2 = x265_lambda2_tab[qp];
>> >> - double chromaLambda = lambda2 / crWeight;
>> >> + double lambda2 = x265_lambda2_tab[qp];
>> >> +
>> >> +#define SPEC_QP(x) X265_MIN(x, QP_MAX_SPEC)
>> >
>> >
>> >> + int effective_chroma_qp = chroma_qp_table[SPEC_QP(qp)] +
>> X265_MAX(qp - QP_MAX_SPEC, 0);
>> >> + double chromaLambda = x265_lambda2_tab[effective_chroma_qp];
>> >> + int chroma_offset_idx = X265_MIN (qp - effective_chroma_qp + 12,
>> MAX_CHROMA_LAMBDA_OFFSET);
>> >> + uint64_t chromaWeight = m_rdCost->psyRdEnabled() ?
>> x265_chroma_lambda2_offset_tab[chroma_offset_idx] : 256;
>> >> +#undef SPEC_QP
>> >
>> >
>> > Luma to chroma qp mapping should be done as mentioned in the HEVC
>> standards. the array chroma_qp_table[] is written according to H.264
>> spec. We cant be using that for HEVC.
>> > g_chromaScale[chFmt][qpc]) - gives the correct mapping of chroma qp as
>> per HEVC spec. chroma qp needs to be obtained from luma qp (0-69) before it
>> can be clipped to QP_MAX_SPEC for HEVC.
>> >
>> >
>> >>
>> >> m_me.setQP(qp);
>> >> m_trQuant->setLambda(lambda2, chromaLambda);
>> >> m_rdCost->setLambda(lambda2, x265_lambda_tab[qp]);
>> >> - m_rdCost->setCbDistortionWeight(cbWeight);
>> >> - m_rdCost->setCrDistortionWeight(crWeight);
>> >> + m_rdCost->setCbDistortionWeight(chromaWeight);
>> >> + m_rdCost->setCrDistortionWeight(chromaWeight);
>> >> }
>> >>
>> >> void TEncSearch::xEncSubdivCbfQT(TComDataCU* cu, uint32_t trDepth,
>> uint32_t absPartIdx, uint32_t absPartIdxStep, uint32_t width, uint32_t
>> height, bool bLuma, bool bChroma)
>> >> diff -r ff3a85f715d4 -r 4d76a9c8b5ab
>> source/Lib/TLibEncoder/TEncSearch.h
>> >> --- a/source/Lib/TLibEncoder/TEncSearch.h Mon Jun 16 16:12:00
>> 2014 +0530
>> >> +++ b/source/Lib/TLibEncoder/TEncSearch.h Mon Jun 16 16:35:16
>> 2014 +0530
>> >> @@ -142,7 +142,7 @@
>> >>
>> >> void setRDGoOnSbacCoder(TEncSbac* rdGoOnSbacCoder) {
>> m_rdGoOnSbacCoder = rdGoOnSbacCoder; }
>> >>
>> >> - void setQP(int QP, double crWeight, double cbWeight);
>> >> + void setQP(int QP);
>> >>
>> >> TEncSearch();
>> >> virtual ~TEncSearch();
>> >> diff -r ff3a85f715d4 -r 4d76a9c8b5ab source/encoder/frameencoder.cpp
>> >> --- a/source/encoder/frameencoder.cpp Mon Jun 16 16:12:00 2014 +0530
>> >> +++ b/source/encoder/frameencoder.cpp Mon Jun 16 16:35:16 2014 +0530
>> >> @@ -363,22 +363,8 @@
>> >> }
>> >>
>> >> void FrameEncoder::setLambda(int qp, int row)
>> >> -{
>> >> - TComSlice* slice = m_pic->getSlice();
>> >> - int chFmt = slice->getSPS()->getChromaFormatIdc();
>> >> -
>> >> - // for RDO
>> >> - // in RdCost there is only one lambda because the luma and chroma
>> bits are not separated,
>> >> - // instead we weight the distortion of chroma.
>> >> - int chromaQPOffset = slice->getPPS()->getChromaCbQpOffset() +
>> slice->getSliceQpDeltaCb();
>> >> - int qpc = Clip3(0, MAX_MAX_QP, qp + chromaQPOffset);
>> >> - double cbWeight = pow(2.0, (qp - g_chromaScale[chFmt][qpc]) /
>> 3.0); // takes into account of the chroma qp mapping and chroma qp Offset
>> >> -
>> >> - chromaQPOffset = slice->getPPS()->getChromaCrQpOffset() +
>> slice->getSliceQpDeltaCr();
>> >> - qpc = Clip3(0, MAX_MAX_QP, qp + chromaQPOffset);
>> >> - double crWeight = pow(2.0, (qp - g_chromaScale[chFmt][qpc]) /
>> 3.0); // takes into account of the chroma qp mapping and chroma qp Offset
>> >> -
>> >> - m_rows[row].m_search.setQP(qp, crWeight, cbWeight);
>> >> +{
>> >> + m_rows[row].m_search.setQP(qp);
>> >> }
>> >>
>> >> void FrameEncoder::compressFrame()
>> >> @@ -387,7 +373,6 @@
>> >> int64_t startCompressTime = x265_mdate();
>> >> TEncEntropy* entropyCoder = getEntropyCoder(0);
>> >> TComSlice* slice = m_pic->getSlice();
>> >> - int chFmt =
>> slice->getSPS()->getChromaFormatIdc();
>> >> int totalCoded = (int)m_top->m_encodedFrameNum -
>> 1;
>> >>
>> >> m_nalCount = 0;
>> >> @@ -515,21 +500,13 @@
>> >> }
>> >>
>> >> int qp = slice->getSliceQp();
>> >> -
>> >> - // for RDO
>> >> - // in RdCost there is only one lambda because the luma and chroma
>> bits are not separated,
>> >> - // instead we weight the distortion of chroma.
>> >> - int qpc;
>> >> - int chromaQPOffset = slice->getPPS()->getChromaCbQpOffset() +
>> slice->getSliceQpDeltaCb();
>> >> - qpc = Clip3(0, MAX_MAX_QP, qp + chromaQPOffset);
>> >> - double cbWeight = pow(2.0, (qp - g_chromaScale[chFmt][qpc]) /
>> 3.0); // takes into account of the chroma qp mapping and chroma qp Offset
>> >> -
>> >> - chromaQPOffset = slice->getPPS()->getChromaCrQpOffset() +
>> slice->getSliceQpDeltaCr();
>> >> - qpc = Clip3(0, MAX_MAX_QP, qp + chromaQPOffset);
>> >> - double crWeight = pow(2.0, (qp - g_chromaScale[chFmt][qpc]) /
>> 3.0); // takes into account of the chroma qp mapping and chroma qp Offset
>> >> -
>> >> +
>> >> double lambda = x265_lambda2_tab[qp];
>> >> - double chromaLambda = lambda / crWeight;
>> >> +
>> >> +#define SPEC_QP(x) X265_MIN(x, QP_MAX_SPEC)
>> >> + int effective_chroma_qp = chroma_qp_table[SPEC_QP(qp)] +
>> X265_MAX(qp - QP_MAX_SPEC, 0);
>> >> + double chromaLambda = x265_lambda2_tab[effective_chroma_qp];
>> >> +#undef SPEC_QP
>> >>
>> >> // NOTE: set SAO lambda every Frame
>> >> m_frameFilter.m_sao.lumaLambda = lambda;
>> >> @@ -539,7 +516,7 @@
>> >> for (int i = 0; i < m_numRows; i++)
>> >> {
>> >> m_rows[i].m_search.m_me.setSourcePlane(fenc->getLumaAddr(),
>> fenc->getStride());
>> >> - m_rows[i].m_search.setQP(qp, crWeight, cbWeight);
>> >> + m_rows[i].m_search.setQP(qp);
>> >> }
>> >>
>> >> // Clip qps back to 0-51 range before encoding
>> >> diff -r ff3a85f715d4 -r 4d76a9c8b5ab source/encoder/rdcost.h
>> >> --- a/source/encoder/rdcost.h Mon Jun 16 16:12:00 2014 +0530
>> >> +++ b/source/encoder/rdcost.h Mon Jun 16 16:35:16 2014 +0530
>> >> @@ -53,14 +53,14 @@
>> >> m_lambdaSAD = (uint64_t)floor(256.0 * lambda);
>> >> }
>> >>
>> >> - void setCbDistortionWeight(double cbDistortionWeight)
>> >> + void setCbDistortionWeight(uint64_t cbDistortionWeight)
>> >> {
>> >> - m_cbDistortionWeight = (uint64_t)floor(256.0 *
>> cbDistortionWeight);
>> >> + m_cbDistortionWeight = cbDistortionWeight;
>> >> }
>> >>
>> >> - void setCrDistortionWeight(double crDistortionWeight)
>> >> + void setCrDistortionWeight(uint64_t crDistortionWeight)
>> >> {
>> >> - m_crDistortionWeight = (uint64_t)floor(256.0 *
>> crDistortionWeight);
>> >> + m_crDistortionWeight = crDistortionWeight;
>> >> }
>> >>
>> >> void setPsyRdScale(double scale)
>> >> _______________________________________________
>> >> x265-devel mailing list
>> >> x265-devel at videolan.org
>> >> https://mailman.videolan.org/listinfo/x265-devel
>> >
>> >
>> >
>> > _______________________________________________
>> > x265-devel mailing list
>> > x265-devel at videolan.org
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>> >
>>
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>>
>
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