[linux-audio-dev] Re: [MusE] More ideas :) [Track freeze] - Alsa Sequencer

Jay Vaughan seclorum at mac.com
Tue Jun 17 05:01:00 UTC 2003

>you are right that for good real-time 'play-ability' one wants the latency
>as low as possible, but I believe that you didn't get my point that the low
>latency should not be achieved at the expense of high jitter. Running a soft
>synth with a latency of 10ms would work perfectly OK, though if that same soft
>synth had a 10ms jitter it would far for easy be audible.

Hi Frank,

Yes, I guess I did miss your point about jitter ... I was under the 
impression you were saying that with regards to soft-synths, people 
don't care about lag as long as the sound quality is good.  I 
apologize for any harshness that came through in my attitude... I 
consider LAD to be prime pioneer territory for new audio hackers, and 
I do get a little zealous in my misguided reproaches, especially when 
de-cloaking from lurk mode.  Bad habit.

It is a fine line.  Nobody knows that better than us, and we work 
hard to make sure we account for factors such as were discussed here!

>Especially during a live performance the low jitter is important. Musicians
>are used to perform with small latency... think about the time it takes
>before the sound emitted from a speaker arrives at the ear.

Well, sure, but I measure latency in terms of "processing-time -> 
audio output", not "audio output -> to my ears".  The latency of 
sound is a constant which nobody can change - not the case with the 
latency of a synthesizer.

>If you are talking about extremely high latency like 200ms or more I agree
>with you. But if recording engineers are whining that a latency of 10ms is
>too high for them to make a mix they better find a new job...

Heh heh.

>I feel amost sorry <grin> for those musicians that are playing electric
>guitars are are a few meters away from their amps. Not to mention those
>realy poor sound engineers doing the live mix for the FOH (front of house)
>PA system of an open air concert (distance from mixing desk to FOH for
>example 50m; causing a whopping 150ms of latency). Despite all of this,
>those magicians do manage to make great sounding music without any concerns
>about the latency.

Sure, operating in that environment is what makes them a professional.

>I noticed that you are working for Access, and have a vague clue where the
>misunderstanding might come from. I presume the Virus DSPs are running the
>algoritms blockless, ie. rendering one sample and streaming it to the DACs.

Our technique is a trade secret which I have no say over, so I can't 
really go into it ... but the assumption is not 100% accurate. 
Christoph has implemented a very innovative approach to solving these 
sorts of problems, lets just say that, and I am yet to see a similar 
implementation outside of extreme academia ...



Jay Vaughan
r&d>>music:technology:synthesizers - www.access-music.de/

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