[LAU] Jack transport - was - Ardour/Muse Jack tempo lock

[Fons Adriaensen]

On Wed, Aug 13, 2014 at 06:48:12AM +0200, Robin Gareus wrote:

> While the user-experience may improve, technically that mechanism only
> makes sense if it is automated (eg a MMC slave or similar).
> 
> A user pressing a button and that event jumping all the fences and hoops
> until it finally reaches jack has a random delay to begin with.

If we can use MIDI and stil play in sync with other musicians
then surely a START command can be propagated to wherever it
needs to arrive with acceptable delay. 

Pro tape decks could start in a few tens of ms at most. That
was perfectly acceptable. And surely we can do better than
that.


> With a modern SSDs the seek and pre-buffer time until the transport is
> ready to roll is likely shorter than the time it takes for a mouse-click
> to be processed by the application on most systems.

Only pre-filling play buffers when a START command arrives is against
all rules of sane RT design. Even when your disk systems are very fast.
And it's easy enough to do it right. 

And yes, some bloated GUI systems can be sluggish but if you want 
your app to be responsive (e.g. for visual editing) you'll have to
do something about that anyway. Nor should it be assumed that a
START command is always given by a mouse click.

Ciao,

-- 
FA

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