Re: [LAU] Value of low-latency in audio?

From: Jonathan E. Brickman <jeb@email-addr-hidden>
Date: Sat Dec 12 2009 - 19:05:06 EET

Just wondering. Without an RT kernel here, my 2 laptops seem to run my 
simple audio needs pretty well at 64msec latency. At least, it's never 
bothered my playing along with computer-generated audio.

I don't do any heavy-duty audio work here. Once I tried Jackrack, put 
one effect in it (that worked) or one amplifer (that worked) but trying 
to use both didn't. But I don't know if that had so much to do with 
latency or lack of RT kernel as with a smallish amount of memory and an 
underpowered processor driving the whole thing. Now that I''ve upgraded 
the memory on both laptops, perhaps it would work? On musicbox, with 
512MB, using a single good quality (larger) soundfont was enough to 
cause problems. With 768MB in it, it works without problems.

I see people on the list running much lower latencies than 64msec, and 
seemingly trying to get even lower ...

So, just wondering.
  

Depends entirely on specifically what you're trying to do.  I'm using my setup as a live-gig MIDI module, in the sense that when I play a note on my keyboard, it sends noteon/noteoff via MIDI to the box, which either (a) puts out that note as close to zero-latency as possible or (b) delays everything, which hurts live cohesion in many ways, not the least being my fellow band-members taking cues from the positions my fingers are in. 

It's true that RAM and CPU are both needed if you're going to use your laptop for effects.  A good sound system can ease the CPU needs some, but not much in the effects zone.  Apart from MIDI event processing, soundfonts are actually perhaps the least resource-intensive music-generation task in my current experience, as long as your sound system is reasonably tweaked, except some simple sound synthesis tasks in well-written code, e.g., some organ-only simulators.  Sophisticated sound synthesis will eat your CPU alive (that's why I bought this AMD X4), as will anything but the simplest effects setup.

Which brings me to a 'hmmm'.  CPU.  GPU?  :-)  Not yet, but we can pray for it :-)

J.E.B.

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Received on Sat Dec 12 20:15:03 2009