[LAD] MIDI jitter - Today for 4 of 4 tests my USB device did pass all tests with success

[Ralf Mardorf]

On Mon, 2010-07-05 at 10:47 +0200, Ralf Mardorf wrote:
> On Mon, 2010-07-05 at 10:33 +0200, Arnout Engelen wrote:
> > On Mon, Jul 05, 2010 at 10:25:23AM +0200, Ralf Mardorf wrote:
> > > So the visually test around 4 ms and ALSA MIDI latency test around 4 ms
> > > from today might be correct results for my computer 
> > 
> > That sounds pretty good then.
> > 
> > > and at least when I got 4 ms for the visually test, the audible result was 
> > > unusable for music, anyway, I still have got some hope.
> > 
> > You might have mentioned it before, but how exactly are you performing your 
> > test of the 'audible result'?
> > 
> > 
> > Arnout
> 
> The hardest test is to record a MIDI groove for kick, snare and hihat.
> 
> I then used my Alesis D4 drum module that don't cause audible jitter
> when using it with the C64 and Atari ST.
> 
> I did record the audio output of the Alesis D4 by Linux, but each
> instrument one after the other, each instrument two times.
> 
> The result:
> 
> Playing one recording of the two recordings for each instrument and the
> groove is broken. It doesn't matter if it's a beautiful McCoy Tyner or a
> stupid Madonna like groove.
> 
> Playing two recordings, but just of one instrument the phasing is not a
> constant phasing, but fluctuating. An early reflection similar effect
> usually isn't the result, but in the worst cases even this is possible.
> 
> Ralf

C64 synced by click and Atari ST synced by SMPTE and the recordings done
by a Yamaha MT44D 4-track cassette recorder a groove wasn't broken and
the phasing was fixed, absolutely constant. Using the same Alesis D4.