Re: [Qtractor-devel] System lock-up on MIDI clocking

[Ralf M. <ral...@al...>]

On Mon, 2014-08-11 at 16:54 +0000, oli_kester wrote:

> What solved this for me was setting the queue timer resolution to
> "system timer (1000Hz)". When I switch to "HR timer (1000000000Hz)" ,
> which I presume is the default, the system locks up after a short play
> time - even in the first bar! I'm not surprised this is what was
> causing issues - a billion Hz is gigantic! Surprised any computer can
> send MIDI signals that fast.

On the quick an inaccurate explanation.

The resolution has nothing to do with MIDI data transmission speed and
those ticks are also another thing, than those ticks that are the
minimal selected sequencer quantisation, IOW the quantisation you get,
if you don't quantise.

The timer resolution is important for sync precision of the hardware,
since the IRQs are more flexible, the more ticks there are.

The best choice by theory would be instead of many ticks, to use "full"
tickless, but it could cause issues.

I get less MIDI jitter when using 1000000000Hz instead of 1000Hz. I
heard the pre-build kernels now tend to provide hr timer loaded by
default, but no 1000Hz, just 250Hz or whatever is a common value.