On Sat, 19 Mar 2005, Steven M. Schultz wrote:
For conditioning like that I use either 'y4mspatialfilter' (with
relatively high thresholds) or 'yuvmedianfilter' (in its 'fast' mode
with a high weight on the center pixel).
Hmm.. Can't use that one in scripts that I want to release until MJPEGTools 0.7 I guess..
As a last step before the encoder perhaps 'y4mdenoise -t 1' would be
a good choice.
I don't know y4mdenoise yet, but is it as non-destructive as 'yuvdenoise -f' is?
Question 2:
Is there any way to denoise the chroma channel, and have the denoise strength depend on the luma channel? It seems that humans are unsensitive
Not at the moment. What can be done is run 'yuvmedianfilter' on the chroma channels only. Use 'yuvmedianfilter -t 0' to disable luma processing.
I will have to try if yuvmedianfilter can have a significant numerical impact without having significant visible effect. I'm looking for filtering methods that will benefit any sort of video material that needs to be reduced to MPEG.
This leads me to the idea to have mpeg2enc perform this sort of numerical conditioning automatically on any input video. Maybe the default output quality of mpeg2enc could improve quite a bit. I read a comparison of mpeg2enc, ffmpeg and the tmpgenc encoder the other day and they found the default output quality of mpeg2enc to be a lot worse than the tmpgemc output. I agree that the default output quality of mpeg2enc isn't exactly phenominal, but you can get *really* good results by properly conditioning the input stream. I guess an encoder like tmpgenc is doing automatic stream conditioning to get such good default output quality...
to subtle chroma changes when the luma is very low (maybe also when it is very high?), so you could perform more aggressive filtering in those area's, saving bits for encoding.
Which is very close (or identical) to the comment I made the other day about "desaturating the lows".
Ah, maybe I picked that up while scanning my mailbox and immediately forgot about it again. Until now. :)
It's possible with 'y4mspatialfilter' and 'yuvmedianfilter' and now
the new 'yuvdenoise' to specify different thresholds/amounts/etc for
chroma and luma.
Please! Please stop teasing me with all the wonders of MJPEGTools CVS. I can't take it anymore! :)
In the Canopus ADVC300 (if you're using or thinking of using DV)
Still on my wish list..
Dik
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