[x264-devel] [PATCH]adaptive lowpass

[Loren Merritt]

On Tue, 26 Jun 2007, Gabriel Bouvigne wrote:

> This patch adds a --lowpass option that does an adaptive lowpass of input, 
> according to Qp level.
> It's a bit similar to the --nr option, except it really does a lowpass (with 
> a transition band) instead of a noise-gate.
>
> It will increase SSIM by a very tiny amount, but will reduce PSNR 
> significantly.
> When you are into the high Qp range (which you should avoid, btw), it helps 
> reducing a bit the big flat quantized areas.

There shouldn't be any zigzag involved in your code. The input of 
x264_lowpass_dct comes straight from sub*_dct without reordering.

Skip the whole process if QP is sufficiently low that it does nothing. 
This would both improve speed and eliminate half of the table.

Aside from being adaptive, does lowpass provide any benefit over a CQM 
which quantizes the high frequencies more?

--Loren Merritt
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