linuxaudio.org

On 05/03/2012 10:43 AM, Joel Roth wrote:

quoted text
> On Thu, May 03, 2012 at 10:21:16AM +0200, Robin Gareus wrote:

>> Capture latency in above message is a wrong. It was reported a while

>> back: check jack-devel archive Dec 2010:

>

> Thanks

>

>> with jack2, there's also the difference of sync (jackd --sync .. -d alsa

>> ...) vs. async mode. The latter adds 1 period of output latency.

>

> I'll need to read about this. --sync is listed in --help,

> but not in the man page.

http://www.grame.fr/~letz/jackdmp.html
> I hope the difference shows up in get_jack_port_latency_range()!
It does. The output latency is one period longer in async mode.
>> see also:

quoted text
>>   http://wiki.linuxaudio.org/wiki/jack_latency_tests

>

> And again. This is very helpful.

> 

This wiki-page is a bit outdated (it's from before the new latency API

was introduced) but item (2) under

http://wiki.linuxaudio.org/wiki/jack_latency_tests#interpretation_and_an...

describes the same bug that you stumbled over.
(1) was actually solved: The additional latency for USB devices comes

from ALSA's USB driver implementation. Clemens explained the details in

the same thread on jack-devel "Re: Differences in latency between USB

and internal audio interfaces"  December 9, 2010.
ciao,

robin
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