Hi Paul :)

[email protected] wrote:
> OK tried a few things as suggested by Ralf:
>
> jackd -- version produces: 103.0.6-etch1

This is a very outdate version, but anyway even this version shouldn't 
be the cause for this kind of latency you've got, but I guess this 
explains the reason why you only have a tab for JACK audio and ALSA MIDI 
for the QjackCtl connections.

> in synaptic (it complains that not all repositories are available) 
> jackd is marked for upgrade (if I'm reading this right) but the 
> current version matches the installed version.

I can imagine, but I'm not sure, that Debian stable isn't Etch any more, 
somebody else from the list should verify this and tell you what to do, 
e.g. to upgrade or not to upgrade jackd and by using what repositories.

> I tried another gig file and there does seem some improvement but 
> can't be entirely sure - there is still noticeable delay using the 
> piano file suggested.
>
> Should I be able to hear delay when 2 pianos are layered, one in LS 
> and 1 as outboard midi?

No there shouldn't be hearable delay. On my machine I'm not able to use 
external MIDI equipment, because of jitter. This means that I don't have 
just latency, but that the MIDI events send by my USB MIDInterface to 
external synth is
completely unusable, because MIDI events sometimes are to early and 
sometimes they are to late.

1. You could have some delay if you play the virtual synth and the 
external synth in unison, but you monitor the external synth by having 
it's output(s) connected to your sound card. If so, the normal latency 
of the soundcard for the virtual synth is only effected by the output 
latency, while the external synth is effected by the input + output latency.

If this should be the problem, try to decrease Frames/Period for JACK 
and for recordings correct the offset, e.g. Qtractor has got an offset 
option.

2. If you've got hearable MIDI jitter, than you have got the same 
problem I've got with Linux. If you need external synth and I bet you do 
so, because they've got a much better sound quality than all those 
virtual synth, try what I do at the moment. I try to make soundfonts of 
my external synth, because I'm short in time I didn't made any soundfont 
until now, by using an application called Swami. I fear that sound fonts 
aren't able to manage layered samples and that there's no GIG editor for 
Linux.

If like to see if there's MIDI jitter, record "four to the floor" at 120 
BPM, so that exactly every 500 msec a beat should start. Take a look to 
the recorded waveforms by using Audacity. There should be a short 
positive or negative delay, depends to the chosen latency correction, 
but there shouldn't be variations for any delay, the distance between 
two beats also must be 500 msecs.

Some kernels are known for MIDI jitter, you can try to get another 
real-time kernel and it might be that your mobo isn't optimal for Linux, 
so in addition you can try to get an upgrade for your BIOS.

I had bad luck with this and I know many people who had the same 
trouble, they are fine now, because they changed the OS for music. I 
still try to find a solution and keep on using Linux only, but because 
of this I'm unable to make the music I like to make.

Btw. this "four to the floor" test don't give any information about if 
Linux is usable or unusable. A little bit jitter is tolerable, but even 
if you don't hear jitter for "four to the floor", when e.g. playing the 
kick by a virtual synth and the hi hat by an external synth, the groove 
can be completely broken, because of jitter.

> If this is just how it is expected to be then that is different from 
> 'I have some sort of problem'. As always, thanks for you help.
>
> Paul

:)
Ralf
_______________________________________________
64studio-users mailing list
[email protected]
http://lists.64studio.com/mailman/listinfo/64studio-users

Reply via email to