Hi David, David F. Place wrote:
> I heard > some acoustical artifacts that I hadn't noticed when I was working in > front of my computer listening through speakers. This extra "buzzing" > sound is quite annoying. It's hard to imagine how my patches are making > it. Does anyone have any wisdom about how to track down and fix these > kind of problems? Are there any usual things you check first? I know you said you checked what happens when you increase the sampling rate, but I would double check and make sure that what you are hearing isn't aliasing. I've found the difference between using an oversampled or otherwise bandwidth-limited oscillator and the normal [phasor~] or a square wave derived from [phasor~] and [expr~ $v1 > 0.5] to be the difference between day and night (or Stockhausen and Donkey Kong). Check 3.audio.examples/J07.oversampling.pd for one anti-aliasing strategy, or better yet compare a normal, ugly, aliased [phasor~] with the anti-aliased one in that example. List archives will turn up loads when you search for "bandwidth limited" as well. Remember that once aliasing gets into a digital signal, no amount of filtering can remove it! If aliasing isn't the problem, then you'd do best to tap a [dac~] into each section of your patch one by one and see where the problem is. I don't think anyone on this list is so psychic they can figure out it long-distance ;-) Other things I would check, however, from experience: 1) Any Amplitude Modulation, Frequency Modulation or other changes in frequency or gain are done with audio signals, or via [pack 0 0] and [line~] with enough interpolation time set on the [pack] to get rid of any "stepping" or "zipper noise". 2) If you are using samples, that you haven't loaded such a large file into a table that the precision drops. You might have to go fishing in the archives to find out exactly how many samples it takes to do this, I can't remember offhand... 3) That you aren't clipping your final levels. Open the file up in a wave editor and see if the peaks hit 0dB. For some CD players even this is too hot, and you might want to aim for something more like -1dB or -3dB. Scout around on the internets for tips on mixing and mastering for CD to get an idea of where people tend to peak their levels. best, Derek -- derek holzer ::: http://www.umatic.nl ::: http://blog.myspace.com/macumbista ---Oblique Strategy # 156: "The tape is now the music" _______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
