[x265] [PATCH 2 of 4] limit TU : use cbf and quantization coefficients to limit recursion

[Bhavna Hariharan]

Hi Deepthi,

On Fri, Oct 7, 2016 at 1:17 PM, Deepthi Nandakumar <
deepthipnandakumar at gmail.com> wrote:

> Kavitha/Bhavana, excellent job! The test metrics look pretty good.
>
>
>
> On Tue, Oct 4, 2016 at 2:50 PM, <kavitha at multicorewareinc.com> wrote:
>
>> # HG changeset patch
>> # User Bhavna Hariharan <bhavna at multicorewareinc.com>
>> # Date 1474620761 -19800
>> #      Fri Sep 23 14:22:41 2016 +0530
>> # Node ID c018bc0ffc156902b1a9a13ecd6996d30d7403df
>> # Parent  c10ef341f4e65883243f78040f52ed06ace99535
>> limit TU : use cbf and quantization coefficients to limit recursion
>>
>> diff -r c10ef341f4e6 -r c018bc0ffc15 source/encoder/search.cpp
>> --- a/source/encoder/search.cpp Tue Oct 04 13:27:48 2016 +0530
>> +++ b/source/encoder/search.cpp Fri Sep 23 14:22:41 2016 +0530
>> @@ -3194,6 +3194,8 @@
>>                  singlePsyEnergy[TEXT_LUMA][0] = nonZeroPsyEnergyY;
>>                  cbfFlag[TEXT_LUMA][0] = !!numSigTSkipY;
>>                  bestTransformMode[TEXT_LUMA][0] = 1;
>> +                if (m_param->limitTU)
>> +                    numSig[TEXT_LUMA][0] = numSigTSkipY;
>>                  uint32_t numCoeffY = 1 << (log2TrSize << 1);
>>                  memcpy(coeffCurY, m_tsCoeff, sizeof(coeff_t) *
>> numCoeffY);
>>                  primitives.cu[partSize].copy_ss(curResiY, strideResiY,
>> m_tsResidual, trSize);
>> @@ -3331,6 +3333,21 @@
>>              fullCost.rdcost = m_rdCost.calcPsyRdCost(fullCost.distortion,
>> fullCost.bits, fullCost.energy);
>>          else
>>              fullCost.rdcost = m_rdCost.calcRdCost(fullCost.distortion,
>> fullCost.bits);
>> +
>> +        if (m_param->limitTU && bCheckSplit)
>> +        {
>> +            // Stop recursion if the TU's energy level is minimal
>> +            if (cbfFlag[TEXT_LUMA][0] == 0)
>> +                bCheckSplit = false;
>>
>
> Agreed.
>
> +            else if (numSig[TEXT_LUMA][0] < (cuGeom.numPartitions / 16))
>> +            {
>> +                uint32_t energy = 0;
>> +                for (uint32_t i = 0; i < cuGeom.numPartitions; i++)
>> +                    energy += abs(coeffCurY[i]);
>> +                if (energy < numSig[TEXT_LUMA][0])
>>
>
> One question, why are we comparing actual coefficient values to number of
> significant coefficients?
>

We want to stop recursion when the energy of TU is low. If the value of
each of the coefficients is minimal (close to 1), the energy will be less
than the number of coefficients.


>
>> +                    bCheckSplit = false;
>> +            }
>> +        }
>>      }
>>
>>      // code sub-blocks
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>>
>
>
>
> --
> Deepthi
>
> _______________________________________________
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Regards,

Bhavna Hariharan
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