On Thu, 8 Jun 2006, E.Chalaron wrote:
> mmm then I must have done something wrong somewhere ....
Not sure what it is - I've used the same frame size and run the
commands I've posted and nary a problem so far.
> Ha .. Ok, in fact I am now exporting most of my transfers to 1024*768 not in
> PAL size. PAL videos in mpeg2 are coming from the quictime 422 1024*768
I think all that doing 2 scaling runs instead of 1 accomplishes is
consume a lot more cpu (and wallclock) time ;)
> > NOTE: Do the y4munsharp and yuvdenoise ON THE SMALLER 4:2:2 frames.
> > It doesn't make sense to denoise the large 4:4:4 frames!
>
> Was wondering actually. I 'll make a couple of trials to see the difference.
Downscaling is a form of "noise reduction". It's also one that is
(almost always) best done first.
> But applying a yuvdenoise - m 4,8,8 on a grainy frame would probably help more
> to reduce the grain than doing after scaling down.. Am I wrong ?
Hmmm, I think so ;) Downscaling will not only decrease the frame size
but will also decrease the size of the grains. Some of the noise might
even get scaled below the threshold of visibility.
That's why small movie clips can look so "good". Those small
(320x240) clips look great on a small screen (or in a small window).
But the same source used to make a larger version (not scaled down)
will look noisy. I've seen that effect quite often.
> Just to make sure I have missed none of them :-)
Oh, ok. I thought you might just make multiple passes over the frame
to make sure no pixels were overlooked ;)
Cheers,
Steven Schultz
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