[x265] [PATCH] rc: fix chroma qp and chroma lambda derivations

[Deepthi Nandakumar]

This looks like a Main bug where rdcost was not looking at g_chromaScale at
all.



On Thu, Dec 4, 2014 at 4:36 PM, <aarthi at multicorewareinc.com> wrote:

> # HG changeset patch
> # User Aarthi Thirumalai
> # Date 1417675781 -19800
> #      Thu Dec 04 12:19:41 2014 +0530
> # Node ID 23061220a5fe287cac893320d8ee0a782d6767c0
> # Parent  511dde5ac1deee96a0105bb87e14670ef5ed72a6
> rc: fix chroma qp and chroma lambda derivations.
>
> fix the chroma qp values for Main10 profile, derive chroma qp from luma qp
> values
> according to the HEVC spec.
> improves quality at high qps.
>
> diff -r 511dde5ac1de -r 23061220a5fe source/common/constants.cpp
> --- a/source/common/constants.cpp       Thu Dec 04 12:43:06 2014 +0530
> +++ b/source/common/constants.cpp       Thu Dec 04 12:19:41 2014 +0530
> @@ -289,11 +289,21 @@
>      {  4, -13, 22, -31, 38, -46, 54, -61, 67, -73, 78, -82, 85, -88, 90,
> -90, 90, -90, 88, -85, 82, -78, 73, -67, 61, -54, 46, -38, 31, -22, 13, -4 }
>  };
>
> +
> +#if HIGH_BIT_DEPTH
> +const uint8_t g_chromaScale[ChromaQPMappingTableSize] =
> +{
> +    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
> 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
> 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
> +    51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51
> +};
> +
> +#else
>  const uint8_t g_chromaScale[ChromaQPMappingTableSize] =
>  {
>      0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
> 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 29, 30, 31, 32, 33, 33, 34, 34, 35,
> 35, 36, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
>      51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51
> -};
> +};
> +#endif
>
>  const uint8_t g_chroma422IntraAngleMappingTable[AngleMapping422TableSize]
> =
>  { 0, 1, 2, 2, 2, 2, 3, 5, 7, 8, 10, 12, 13, 15, 17, 18, 19, 20, 21, 22,
> 23, 23, 24, 24, 25, 25, 26, 27, 27, 28, 28, 29, 29, 30, 31, DM_CHROMA_IDX };
> diff -r 511dde5ac1de -r 23061220a5fe source/encoder/rdcost.h
> --- a/source/encoder/rdcost.h   Thu Dec 04 12:43:06 2014 +0530
> +++ b/source/encoder/rdcost.h   Thu Dec 04 12:19:41 2014 +0530
> @@ -57,12 +57,12 @@
>
>          setLambda(x265_lambda2_tab[qp], x265_lambda_tab[qp]);
>
> -        int qpCb = Clip3(QP_MIN, QP_MAX_MAX, qp +
> slice.m_pps->chromaQpOffset[0]);
> +        int qpCb = Clip3(QP_MIN, QP_MAX_MAX, (int)g_chromaScale[qp +
> slice.m_pps->chromaQpOffset[0]]);
>          int chroma_offset_idx = X265_MIN(qp - qpCb + 12,
> MAX_CHROMA_LAMBDA_OFFSET);
>          uint16_t lambdaOffset = m_psyRd ?
> x265_chroma_lambda2_offset_tab[chroma_offset_idx] : 256;
>          setCbDistortionWeight(lambdaOffset);
>
> -        int qpCr = Clip3(QP_MIN, QP_MAX_MAX, qp +
> slice.m_pps->chromaQpOffset[1]);
> +        int qpCr = Clip3(QP_MIN, QP_MAX_MAX, (int)g_chromaScale[qp +
> slice.m_pps->chromaQpOffset[0]]);
>          chroma_offset_idx = X265_MIN(qp - qpCr + 12,
> MAX_CHROMA_LAMBDA_OFFSET);
>          lambdaOffset = m_psyRd ?
> x265_chroma_lambda2_offset_tab[chroma_offset_idx] : 256;
>          setCrDistortionWeight(lambdaOffset);
> diff -r 511dde5ac1de -r 23061220a5fe source/encoder/sao.cpp
> --- a/source/encoder/sao.cpp    Thu Dec 04 12:43:06 2014 +0530
> +++ b/source/encoder/sao.cpp    Thu Dec 04 12:19:41 2014 +0530
> @@ -177,7 +177,7 @@
>  {
>      Slice* slice = frame->m_encData->m_slice;
>
> -    int qpCb = Clip3(0, QP_MAX_MAX, qp + slice->m_pps->chromaQpOffset[0]);
> +    int qpCb = Clip3(QP_MIN, QP_MAX_MAX, (int)g_chromaScale[qp +
> slice->m_pps->chromaQpOffset[0]]);
>      m_lumaLambda = x265_lambda2_tab[qp];
>      m_chromaLambda = x265_lambda2_tab[qpCb]; // Use Cb QP for SAO chroma
>      m_frame = frame;
> _______________________________________________
> x265-devel mailing list
> x265-devel at videolan.org
> https://mailman.videolan.org/listinfo/x265-devel
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.videolan.org/pipermail/x265-devel/attachments/20141204/a148deb8/attachment.html>