Re: [LAU] jack/oversampling

On Sun, Mar 16, 2014 at 05:45:22PM +0100, tim wrote: You should not have any non-linearities, except those introduced on purpose, i.e. distortion plugins and the like. And then it all depends on how these are designed. If done well, they will not add any aliased components. One way to avoid that is using higher sample rates internally, but it's not the only one. Fractional delays are possible at any rate, to any precision. The only limit is that you can't have very short ones (as the output would depend on future samples). Assuming the filter is _tuned_ correctly (e.g. the centre frequency for a parametric is corrected for warping), there will be a difference in the actual shape of the FR. But there is _no_ reason to assume that the original 'analog' shape is any better (or worse) than the warped one. No. If a filter requires double precision to avoid problems then you made a bad choice of filter architecture. Lots of plugins, (usually using 'textbook' biquads) fail in this way. It's perfectly possible to create audio filters that work perfectly even in 16-bit fixed point format (with a higher precision multiply). A lot of research went into this in the early years of digital audio - just look up the AES journals from the 1970s. The solution is to understand the problem and use the correct filter architecture, not the brute force method of using doubles blindly. Only if you use 'primitive' algorithms. Unfortunately there's a lot of those around. In summary, 96 or 192 kHz will allow you to use simpler algorithms. That may be a good reason for higher sampler rates, but it doesn't mean you can't have the same performance at 48 kHz. Another good reason for higher sampling rates is that the antialising filters in the converters can have a much wider transition band (assuming you don't actually use the higher bandwidth), leading to much reduced latency. It's the reason why 'digital snakes' used in PA system usually work at 96 kHz. By starting the transition band at 24 kHz or so they can use very short filters, a fraction of a millisecond for some. The same matter makes all the difference between 44.1 and 48 kHz. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow)