Re: core midi time stamping
Re: core midi time stamping
- Subject: Re: core midi time stamping
- From: Brian Willoughby <email@hidden>
- Date: Fri, 15 Jul 2005 04:40:42 -0700
Your marketing folks may be thinking specifically of USB MIDI interfaces.
The USB standard allows for 1ms polling at best. While I imagine that all
MIDI interfaces will be set to poll at the fastest rate, there is still no
absolute guarantee in the USB spec that an interrupt will be serviced during
its first time slice. Heavy loads could cause a interrupt service to be
delayed to a subsequent time slot. Therefore, USB-MIDI has a random latency
which averages .5ms at best, but really is not bounded.
A custom driver is required to get better MIDI latency performance than this
over USB.
I have no experience with the limitations of FireWire for MIDI time stamping.
At any rate, CoreMIDI will always provide MIDI time stamping features on both
input and output. However, the performance may vary depending upon the bus,
and custom drivers can significantly improve latency.
Brian Willoughby
Sound Consulting
Begin forwarded message:
From: david tay <email@hidden>
How is core midi time stamping done? Product marketing thinks that
some special code is required.
Would special drivers for MIDI interfaces be required to for midi
time stamping to work?
Thanks,
David
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