[MEncoder-users] lavc option nr

[Jan Paul Schmidt]

Hi there,

does anybody know, how the lavc option nr works? I tried this kind of 
noise reduction on a cartoon - ripped from a PAL DVD -, but the result 
is strange. At the GOP boundaries a high quantiziser is used and it 
looks like the picture have a sort of pump effect. This is not the case 
when leaving the nr option out.

Everything started out with my usual SVCD script, but after trial and 
error this was left to reproduce this behaviour:

	mencoder -oac copy -ovc lavc -lavcopts 
vcodec=mpeg2video:vbitrate=2500:vrc_buf_size=917:keyint=15:nr=400 -o 
pass1.avi episode1.mpg

Note: This is not how I encode SVCDs. This is a very basic command 
without filters and advanced options, which can reproduce this 
behaviour. Bringing back the filters and advanced options do not cure 
the problem.

When using . to cycle through the frames the picture at the GOP 
boundary gets real blocky for one frame and then gets back to normal. I 
also tested it with MPEG 4:

	mencoder -oac copy -ovc lavc -lavcopts 
vcodec=mpeg4:vbitrate=2500:keyint=15:nr=400 -o pass1.avi episode1.mpg

but the result suffers from the same problem. The effect can be noticed 
really good when white text is on a black background.

This is a recent cvs checkout of mplayer and lavc.

Any ideas? Can someone reproduce this?

jps