[linux-audio-dev] XAP: Some thoughts on control ramping

Steve Harris S.W.Harris at ecs.soton.ac.uk
Mon Jan 20 10:23:02 UTC 2003


On Mon, Jan 20, 2003 at 04:13:17 +0100, David Olofson wrote:
> 	5) A more serious issue is that if control events are not
> 	   allowed while ramping, except at the time of the aim
> 	   point, there is no way to avoid sending one RAMP event
> 	   for each block while ramping. You can't aim further
> 	   ahead than the first frame of the next block, or you
> 	   might have to break in and adjust the aim before you
> 	   hit the aim point.

I dont see why there is a restriction on aiming further ahead than the
current block, this seems like a mistake. It forces the plugins to be
closed to linear than is desirable.
 
> Questions:
> 
> 	A) Is it necessary to require that aim points are
> 	   within the current block, to avoid "re-aiming"?

I dont see why, the obvoius inner loop for ramp aiming should deal with
this perfectly well, it will just replace the delta_control number.
 
> 	B) Is STOP useful enough to be in XAP?

I'd argue for it not be be there. Its hard to see when it would be
useful ,ad its one more thing to handle.

SET /could/ be done with a ramp with target time of 0, not optimally efficeint,
but the cases I can think of it wont hurt:

notched switches: will always jump to the target value anyway, so wont
have to do any interpolation.

continuous controls: SET operations will be quite unusual, and the
overhead is not that big.

- Steve, minimalist ;)



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