pippin wrote: > Yea. But that was my point. Unless you know exactly what your waveform > is you are just as likely to AMPLIFY your noise than to SMOOTH your > signal. To really be able to "smooth" you'd have to analyse the whole > signal spectrum and you'd have to do that over some time - ideally the > whole file(to know the dynamic range). But sox doesn't do that it just > looks at a few samples. For the same reason DACs don't do it: it would > introduce too much delay and require too much buffering and processing > power. > > I mean... I can call everything a "smoothing" filter, I can also call > lead "grey gold". What it actually does is another story, though.
Hi Pippin You were asking about the algorithm used in digital interpolation filters for up/oversampling. I was talking about something else, the smoothing filter (aka reconstruction, anti-imaging filter). This was in relation to your and Darren's objection to the term stair steps. In practice, a DAC does not attempt to recreate voltage impulses, instead it uses a zero-order hold process - i.e. it does in fact output stair stepped voltages. The end results is much the same, with quantisation error and infinite Nyquist images, but with a deterministic roll-off. The smoothing filter is then the low-pass filter 'at' Nyquist - which if (and all stages of sampling) ideal, would perfectly recreate the sampled function. ------------------------------------------------------------------------ flimflam's Profile: http://forums.slimdevices.com/member.php?userid=56891 View this thread: http://forums.slimdevices.com/showthread.php?t=99088 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
