Temporal-ID support for VCU Encoder - 2023.1 English

H.264/H.265 Video Codec Unit v1.2 Solutions LogiCORE IP Product Guide (PG252)

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2023.1 English

The VCU encoder assigns a temporal layer ID to each frame based on its hierarchical layer as per the AVC/HEVC standard. This enables having a temporal-ID based QP and the Lambda table control for encode session. This is for Pyramidal GOP only.

Frame Delta-QP Option Based on temporal-ID

Encoder rate control assigns the QP based on rate-control algorithm type and target-rate. You can choose an extra delta-QP based on its temporal-ID on top of the rate-control generated QPs. This enables you to increase or decrease the picture quality based on the temporal layers IDs. As you go higher up the layers, it is better to have a higher average QP to maintain better subjective quality. Example: If Layer0 - QPs = "X", and Layer1 is "X + 2", and Layer2 is "X+4," then deltaQPs should be set as 2 and 4 accordingly for Layer1 and Layer2.

Not Supported: RateCtrlMode=CONST_QP is not supported for delta_QP

To enable delta-QP option, enable the following parameter in the cfg file.

Gop.TempDQP        = 1 1 1 1

LOAD_LDA Based on Temporal ID

Similarly, having different base frame QPs depending on the temporal layer, you can choose different a Lambda table for different layers. This improves the subjective quality depending on video content. To enable a temporal ID, enable the following parameter in the cfg file and copy Lambdas.hex file in the working directory. Refer to the 5.1.3 Lambda File Format

LambdaFactors = 0.20 0.35 0.59 0.60 0.61 0.62