I think extent of the ringing artifacts depend on the source images being encoded. If the spatial bandwidth of the signal hitting mpeg2enc has already been limited (by camera optics, preprocessing, etc) then at higher spatial frequencies the spectrum will already roll off, and will probably be less effected by --reduce-hf. I should probably grab some "busy" screenshots and pull them into matlab to estimate what the spatial bandwidth of my camera really is.
Now in general, ringing tends to occur when bandlimiting is done with a sharp-transition lowpass filter, as the impulse (time) response of a sharp filter rings out for a while. The same thing happens when you throw out high-frequency DFT/DCT bins, which I'm assuming is happening here (I not familiar enough with mpeg2 encoding in general and mpeg2enc in specific to be sure). If so, it might make sense to add some control both to which bins are kept, and to how the encoder transitions between keeping and not keeping them. Or, perhaps we just need a linear spatial-filtering routine to complement yuvdenoise (adaptive temporal filtering) and yuvmedianfilter (nonlinear spatial filtering) that allows for a programmable spatial frequency reduction (basically, like yuvscaler/y4mscaler but without the decimation step). This could be done so that edges are a little softened rather than ring. I'm assuming that if the input has little content in a bin, then the encoder will save bits. Dan ------------------------------------------------------- This SF.net email is sponsored by:Crypto Challenge is now open! Get cracking and register here for some mind boggling fun and the chance of winning an Apple iPod: http://ads.sourceforge.net/cgi-bin/redirect.pl?thaw0031en _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
