[sdiy] USAMO

[Nantonos]

Hello Neil,

Thursday, March 26, 2015, 3:36:09 PM, you wrote:

>> That page says
>>
>>   "Because the MIDI signals are generated and transported as audio,
>>   they are guaranteed to be sample-accurately synced with your audio,
>>   and free of the jitter often associated with computer-generated
>>   MIDI."
>>
>> this seems to be an inaccurate claim. It would be possible to do this,
>> but the same box would need to either have several channels of audio
>> in and out (plus preamps, etc) to be sample-accurate *with*, or
>> alternatively some digital in-out, for example ADAT, plus a wordclock
>> source so that some other box could be kept aligned to a granularity
>> of one sample.
>>
>> As a standalone box, its not sample-accurate with anything else.

> I think the point here is that, by being sample-accurate to itself
> (which is all it can be) it removes the OS timing jitter that would
> otherwise get with a direct MIDI out.

I agree that it is likely to improve things over the latency and jitter
you would get from MIDI-over-DIN on your audio interface, or
MIDI-over-USB (with faster transmission speed but several ms of
latency from USB packet assembly and dispatch).

> Not to mention the fact that a single MIDI event in a DAW may be
> time-accurate to within +/-21us (@48kHz), but considering most common
> MIDI messages are 3 bytes long it will take ~960us before the
> receiving MIDI instrument has enough information to do something.

Yes. I just felt that "sample accurate" was promising way more than
could actually be delivered.

I occasionally wonder whether a MIDI over serial (but using something
like single drop, full duplex RS485 at 1Mbit/s) would be a worthwhile
improvement

-- 
Best regards,
 Nantonos                            mailto:nantonos at epona.net