Re: [Jack-Devel] Call for testing of MIDI Drivers in JACK 2

On Wed, Apr 6, 2011 at 9:24 PM, Devin Anderson <[hidden]> wrote:

> I did occasionally reference the ALSA raw driver when I was writing
> the 'alsarawmidi' driver; however, the code design is somewhat
> different, and the driver doesn't have the same problems with scaling
> and MIDI jitter that the ALSA raw and seq drivers have (with my
> hardware, MIDI jitter would become more and more apparent as more
> ports were used), or the problems with very low latencies and jitter
> that the ALSA seq driver has.  Of course, I've only tested the driver
> on my own hardware so far, which is one of the reasons I sent out this
> message in the first place.

the key thing is to have your own thread that does the i/o. and maybe
uses poll(2). most importantly is timestamping, which it sounds if you
are doing if you're handling jitter.

> Are you referring to:
>
>    http://trac.jackaudio.org/browser/trunk/jack/drivers/a2j

yes.

> ?  If so, I've looked at it.  IIRC, it handles MIDI input using a
> 'seq' interface, but doesn't handle MIDI output.  I don't remember if
> it interfaces with hardware ports, virtual ports, or both.  The
> 'alsarawmidi' driver only interfaces with hardware ports.

it interfaces with both h/w and virtual ports, but yes, via the seq
API. and yeah, right now, its input only but thats a detail because
the code is there to do both.

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