[x265] [PATCH 2 of 3] lambda: change chroma lambda distortion weighting to resemble x264
Aarthi Priya Thirumalai
aarthi at multicorewareinc.com
Mon Jun 16 14:08:38 CEST 2014
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)
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>
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