[PD] accuracy of signal/message-objects

[martin.peach at sympatico.ca]

> Frank Barknecht wrote:
> Hallo,
> martin.peach at sympatico.ca hat gesagt: // martin.peach at sympatico.ca wrote:
> 
> > [metro] is very accurate over time, it just has a jitter as the
> > bangs have to happen in between sample blocks
> 
> What do you mean by this "bangs have to happen in between sample
> blocks"? The bangs from metro AFAIK happen independent from the sample
> blocks.

I think the bangs are independent but they don't get processed until any pending samples have been dealt with.
That was the impression I got when testing [comport] by setting the DTR pin using [metro]: there is always a jitter of a few milliseconds. Maybe it's the OS that causes the jitter, but it was about the same on WinXP and linux.
Also looking at the pd code, as far as I could follow it, the control signals seem to be processed in between signal blocks, so that, for instance, a metro bang that happens in the middle of a signal block will not be processed until after that block, so yes, the metro can tick whenever it wants but the bang won't occur until after the current sample block has been processed. If it happens to tick in between sample blocks then the bang will happen at the correct time.

Martin