Is there a need to apply Deblocking filter, when I have all Intra frames Encoding

Question

I am working on H.264 Deblocking Filter and need some clarity.

• While designing an all Intra Encoder and Decoder, is it mandatory to add Deblocking Filter block in the Codec.
• If deblocking filter is not enabled for all Intra Encoding does that cause any PSNR degradation(I checked few streams the PSNR almost remained the same).
• If I am encoding all my frames using Intra prediction, does that also have any blocking artifacts.

Thanks in advance

Answer 1

You can skip deblocking filter on the decoder side. For all intra encoding, since the mismatch caused by deblocking filter will not be propagated to the next frame, the quality degradation may not be obvious.

Answer 2

• According to https://en.wikipedia.org/wiki/Deblocking_filter, the deblocking filter is NOT optional.
• There might not be a substantial PSNR degradation when deblocking is not enabled, however, the perceptual quality will probably decrease if the blockiness increases.
• Yes, blocking artifacts are independent of inter/intra encoding. They are caused by quantization, which (depending on the strength) will basically get rid of high frequencies and thus lead to blocking artifacts.