[music-dsp] sampler pops and clicks

[Daniel Werner]

adam wrote:

>
> An envelope that has imperceptibly fast attack and decay, more like 
> windowing function than an audible ADSR. I don't think you'd want a 
> low-pass filter applied all the time unless you have a really high 
> sample rate (high enough that you could use a filter with a cutoff 
> above 20kHz so as not to affect your instrument's frequency response) 
> and DSP cycles to burn. A ramp-in, ramp-out will provide a low-pass 
> effect that is localized to only a few samples (<1ms), so you don't 
> hear it, you just don't hear a click. Not all professional samplers do 
> this, however, or they do it to different degrees. My K2500 sounds 
> every different with samples that start with a non-zero sample, vs 
> ones that I pre-fade to zero over a few samples at each end using a 
> sound editor. The non-zero-starting samples have "snap" for lack of a 
> better description.
>
> -Adam

I think if the sample starts at a non-zero value you should not ramp it 
in unless the user has specified an envelope, so the "snap" you 
described is preserved (users may want this). What i'm wondering is when 
one note is playing and another cuts it off, there will be a transition 
between the current (non-zero) sample and the first (zero) sample. I 
think if a lot of hardware samplers do nothing to prevent this then I 
won't either, it really doesn't bother me. My problem with ramping is 
this: my program processes messages in blocks, and a note on message can 
be received by the sampler for the first sample of the block, and to 
have sample accurate timing it has to trigger the sample playing 
straight away, with no time to fade out and in again. I don't own a 
sampler but I know you can hear audible clicks in some SoundTracker 
.MODs when a new note is triggered on a channel where a note is already 
still playing.

- Daniel