Re: [Linuxsampler-devel] Re: [Linuxsampler-devel] RAM sampler module proposal

[Phil K. <phi...@el...>]

The MIDI spec defines the bit pattern as one start bit, eight data bits
and one stop bit with a transfer rate of 31.25 (+/- 1%) Kbaud, hence 10
bits per message byte.

Although this speed is the official spec I've found that ALSA, and a
number of MIDI cards, do not seem to throttle data back to the spec and
will pass data though the interface at reception speed.  Although this
is a wider problem for me regarding DMIDI and hardware it's potentially
a good thing when we are dealing with software based D/MIDI applications
(10 Gbit MIDI :).  

So regarding MIDI timing I get the impression that PC host based
interfaces cannot guarantee the 31.25k rate, but testing is not
conclusive.

-P

On Fri, 2002-11-08 at 11:29, chr...@ep... wrote:
> >Further to this, serial MIDI only runs at 31.250 kbaud, which means that
> >the maximum resolution of a MIDI note on is 42 samples at 44.1kHz (30 bits
> >at 31250bits/s).
> >
> >Obviously things like OSC have greater time resolution, but it shows that
> >sample accurate note triggering isn't essential. It may something worth
> >droppping for efficiency.
> 
> I definitely agree with that, as notes will be triggered by pure MIDI
> devices in most cases anyway. And even if not, sample accurate triggering
> is just overkill.
> 
> I think doubling MIDIs frequency (in case of note on that would be
> 2*1067Hz = 2133Hz) would be enough for the internal rate. That way you
> preserve at least MIDIs resolution, no?
> 
> (BTW note on has 3 Bytes, what are the remaining 6 Bits for? CRC?)
> 
> 
> 
> 
> 
> 
> 
> 
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