On Mar 30, 2006, at 12:52 AM, linux-audio-dev- [EMAIL PROTECTED] wrote:
Maybe I haven't made myself clear. IMHO linear resampling sucks for audio. It is included in libsamplerate purely so I can show how bad it actually is.
"Vintage" gear from the first few decades of digital audio were largely implemented using linear resampling. As a result, the linear aliasing characteristics have become an "effect" that artists are actively looking for in some situations. Ditto drop-sample resampling (Ensoniq Mirage). So I think it makes sense to make it as fast as it can be, and present it as an option. "Bitcrusher" plug-ins are popular for a reason :-). This paper (sadly not available online): D. Rossum, ``Constraint based audio interpolators,'' Proceedings of the IEEE Workshop on Applications of Signal Processing to Audio and Acoustics, New Paltz, NY, 1993. Shows why linear sampling can often sound "good enough" in practice. Basically, in linear resampling some of the high-energy aliases are masked by the signal. The paper shows how this property isn't present for some of the resamplers that are higher-order than linear but lower-order than sync interpolators. So, if you can't afford to do a sync interpolator, you have to be careful what alternative you choose, or else you may end up with something that sounds worse than linear! --- John Lazzaro http://www.cs.berkeley.edu/~lazzaro lazzaro [at] cs [dot] berkeley [dot] edu ---