[PD] 0 latency

[Lao Yu]

Zero latency is a marketing slogan but it is physically impossible.  
the only way to have something close to that would be monitoring  
BEFORE the AD converter. even a stand-alone digital tape recorder has  
a few ms of latency simply caused by A/D and then D/A conversion.  
reducing the sample rate doesn't change the latency. but Frank said  
all that already.
you need to find latency in the settings of your interface. in pd you  
set the latency in the 'delay' value of the audio settings dialog or  
in the settings of jack (I don't know which you use). The default is  
50ms which is too high for my taste for life music. The lower your  
latency setting the higher the CPU load. Set it to a time value that  
you can accept without pulling too much power out of your machine.

Best
Jurgen

On Dec 28, 2008, at 12:11 AM, Frank Barknecht wrote:

> Hallo,
> Juan Felipe Mejia hat gesagt: // Juan Felipe Mejia wrote:
>
>> hi everyone, im a beggining to work with Puredata and a TD 9  
>> Roland v-
>> drums.
>> I'm using a MOTU ultralite mk3 as my in-out audio divice.
>> I work with a MacBook Pro, 2.5 Ghz Intel core duo, 4 GB of ram.
>>
>> Until now almost everything is working properly but the latency.
>> Does anyone now how to get the 0 latency en puredata?
>
> Zero latency is impossible in a computer software if you do some
> processing of the incoming data before sending it out again.
>
>> i've tried to reduce the sample rate to 30000 and even lower, the  
>> same
>> with the delay but there is still some latency.
>> Lower than 30000 works better but the sound quality is bad.
>
> Generally latency shrinks with higher samplerates and gets larger with
> lower rates, provided you have the same blocksize.
>
>> I tried AudioDesk (the software that comes with the MOTU) to make  
>> some
>> live recordings and there were no delay, no latency.
>
> Probably the soundcard is sending incoming data straight through,  
> so no
> processing is going on. Otherwise see above: Technically 0 latency is
> impossible.
>
> Ciao
> -- 
> Frank
>
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