cliveb;130937 Wrote: > As the terms are typically used, it's OVERSAMPLING rather than > UPSAMPLING that shifts aliasing higher up the frequency range and makes > life easier for the filters. Pretty much every DAC on the planet does > oversampling these days (with the exception of the niche NOS ones, > which some might consider to be out on the fringe). It's mathematically > sound. > > In contrast, upsampling (as the term is generally used) involves > INVENTING additional data (usually by interpolation) in the expectation > that it will deliver improved high frequency resolution. But this extra > data that's invented can't ever be known to be correct. Quite a lot of > the time, it'll be wrong. It doesn't "recreate" the high frequencies > that were discarded when the recording was sampled at whatever lower > frequency was used - that's impossible (as Sean pointed out earlier). > In other words, the additional high frequencies generated are NOISE > and/or DISTORTION. So how come people think upsampled digital audio > sounds better? Maybe for the same reason that they think that analogue > sounds better: that noise/distortion might actually be euphonic (if > it's audible at all).
I think you are inventing a distinction that doesn't really exist. Oversampling, as has been done for ages internally in CD players, also "invents" data, since the oversampled word stream is run through a digital FIR filter whose task it is to filter away, in the digital domain, mirror images above 20 kHz. Doing so allows the filter to be phase-linear, which is not possible in the analogue domain. (In the olden days an extremely steep analogue filter tried to remove anything above 20kHz, resulting in massive phase shift in the treble region.) -- P Floding ------------------------------------------------------------------------ P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=26685 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
