[LAU] Are RT-patches needed anymore? (Was Re: >= 2.6.27 RT ETA?)

Jörn Nettingsmeier nettings at folkwang-hochschule.de
Tue Jan 27 10:05:41 EST 2009


Svend-Erik Kjær Madsen wrote:
> On tir, 2009-01-27 at 15:03 +0100, Cassiel wrote:
> 
>> 5.3ms latencies: If you can't sense it... you don't need it
>>
>> r  
> 
> 
> Okay I allways learned that you should't be to proud to admit when your
> wrong. 
> 
> I just ran a few test with a keyboard playing both the keyboard's
> soundmodule and through midi and Qsynth, and I must admit that latency
> was down to 1.3 ms before the audible time differece disapeard.

to put things in perspective:

the speed of sound in air is around 340m/s. that means that in one
millisecond, the sound travels about 34 cm.

anything under a few ms total systems latency will not be noticeable in
a normal listening environment, because you don't stick your head into
the speakers. a drummer hitting a crash cymbal will have 3ms latency
before the sound reaches his/her ears.

a normal, 2m wide stereo triangle will introduce at least 6 ms latency.

most jazz players i know are perfectly comfortable playing live on stage
while being a few meters apart (true, bass and drums prefer to sit next
to each other, but that will still mean 6-12 ms one-way latency).




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