[PD] midi latency pd -> alsa / jackd

Simon Wise simonzwise at gmail.com
Thu Jul 19 05:11:26 CEST 2012

On 19/07/12 00:40, Rob Bothof wrote:
> thanx for your response Simon,
> I've been tweeking with the usb endpoints on my device and have already gotten a
> faster and steadier performance with alsa-midi via jack.
> but it is a balance of how many bytes you can send at the same time and at what
> speed, as usb midi also support a bulk mode..you can
> send up to 64bytes of midi messages at a single call but without a speed request.
> but for my purpose right now it works best with 4bytes at 1ms interrupt...as
> usbmidi is 4bytes i can send 1 message at the time
> if wanted to use 8 so i can always send the platter info and another
> midi-message at the same time but then i need to adjust the speed already
> for it to work properly
> though connecting Pd directly to /dev/midi1 has no problem with all this.....i
> believe jack alsa-midi does a tme sync for midi with the audio.
> i'm going to see if i can write a simple jackd wrapper for oss /dev/midi from
> one of the jack simple midi examples, or perhaps someone already did..
> it seems a bit useless as the oss usb device is probably an emulation of alsa
> who is really driving the device, but maybe it works

well, let us know how it goes ... I've been meaning to explore this area a bit 
more and how you get things working will be interesting.


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