[MEncoder-users] Fwd: Questions on Mencoder performace

[Phil Ehrens]

RC wrote:
> On Tue, 6 Jun 2006 08:26:54 -0700
> Phil Ehrens <phil at slug.org> wrote:
> 
> > I've done pretty extensive testing of nr, and 1000 has not been too
> > much on very clean dvd source, very noisy dvd source, or any dvd
> > source at all.
> 
> I've done rather extensive testing myself.
> 
> After about 600, video starts getting noticably blocky, particularly in
> dark scenes, clouds, etc.  And as you get to about 600, the PSNR
> stops increasing, and starts decreasing.
> 
> I find 300 is close to the best default.

Strange. I am getting no blockiness at all. I am using a target
bitrate of 2400 kbps and seeing actual average bitrates as low
as 800 kbps for very noisy material. For the very clean material
with high action the average bitrate is 2400 kbps, and there is
no blocking at all. Again, this is for 2-pass encodes. For single
pass the image degrades rapidly above nr=200.

I wonder why we are seeing such different behaviour? Maybe nr
interacts badly with some other options or filters? My tests
are all dvd -> lavc mpeg4 with no resizing, just cropping.