[LAD] basic MIDI note-on/note-off questions

[Ralf Mardorf]

On Fri, 2010-06-25 at 14:38 +0200, Ralf Mardorf wrote:
> On Fri, 2010-06-25 at 08:29 -0400, Paul Davis wrote:
> > On Fri, Jun 25, 2010 at 6:55 AM, James Morris <james at jwm-art.net> wrote:
> > > Hi,
> > >
> > > I keep getting surprised at some of the most basic problems I run
> > > into... This time, processing order.
> > 
> > just remember that in "real" MIDI, nothing can be simultaneous. its a
> > serial protocol without timestamps. with traditional serial MIDI, the
> > time interval between bits and bytes is also fixed, creating a fixed
> > minimal interval between any two note on/off messages.
> 
> In addition, the UART gives information about being ready to send. It's
> not fixed to e.g. 1ms. There's a register giving this information.

Note, there's nothing fixed, the limitation is just for the max Baud
MIDI is able to do. Regarding to the term 'fixed' UART is for 'Universal
Asynchronous Receiver Transmitter', the important word is
'Asynchronous'. We are talking about microseconds, taking care about the
CTS and RTS registers. Regarding to all that MIDI jitter, I wonder if
ALSA seq, might has to do with it. I don't know, perhaps there are
issues for USB specifications, but maybe there's something bad for this
'timestamp' routs.

*?*

I programmed on Assembler directly using the UART and there never was
jitter.

Could this be a reason for MIDI jitter using Linux or has it nothing to
do with it? Because, at the other hand there's no jitter internal the
studio in the box.

*?*

Ralf