[LAT] To much latency

[Jeremy Jongepier]

On 10/30/2011 12:55 PM, Dave Stikkolorum wrote:
>
>
> On 30-10-11 12:25, Jeremy Jongepier wrote:
>> On 10/30/2011 12:02 PM, Dave Stikkolorum wrote:
>>> Hi,
>>>
>>> I am a musician and programmer.
>>>
>>> I use a laptop with an internal soundcard (intel)
>>> and ubuntu studo.
>>>
>>> When I see the qjack control settings window
>>> I always see a 46.6 ms latency.
>>>
>>> On a older Desktop computer with an internal ac97 soundcard
>>> or an pci sweex (cheap) I have the same problem.
>>>
>>> Reducing the sample period to 512 , reduces the latency, but
>>> always ends up with problems.
>>>
>>> My question is how to have a good studio setup
>>> for recording (and playing midi in the background)?
>>>
>>> Is it possible to better the performance with an external soundcard?
>>> What are your experiences?
>>>
>>> I also tried ccma an av linux, but the same problems.
>>>
>>> Anyone suggestions?
>>>
>>> Regards,
>>>
>>> Dave Stikkolorum
>>
>> Hello Dave,
>>
>> 46.4ms is the default JACK latency (1024 frames / 44100 sample rate *
>> 2 periods). You can try lowering it by reducing the number of frames.
>> But if you get xruns then (buffer errors) then you may need to
>> optimize your Ubuntu install. You might want to look here:
>> http://wiki.linuxmusicians.com/doku.php?id=system_configuration
> I certainly will read that, thnx!
>> And it's possible to get better performance with an external
>> soundcard, especially compared to onboard cards and specifically in
>> the case of ac97 soundcards. The latter just refuse to work at lower
>> latencies (at least for me). There are quite some soundcards available
>> that yield good performance and that are compatible with Linux:
>> http://wiki.linuxaudio.org/wiki/current_audio_gear
>>
> That sounds promising.
>
>> For starters could you run cat /proc/asound/cards in a terminal on the
>> laptop with the Intel soundcard?
>>
> cat /proc/asound/cards
> 0 [Intel ]: HDA-Intel - HDA Intel
> HDA Intel at 0xdb320000 irq 47
>

Oops, sorry, I meant cat /proc/asound/card*/codec* | grep -i codec
But thanks!

> How much does the processor has influence.
>

The lower the latency the more CPU that will consume.

> For example I have a 1,8 Ghz Pentium 4 upstairs.
>

That will work, I'm using JACK with a netbook which has a 1,2Ghz CPU. 
But then I quickly hit the limits of what this netbook is capable of. 
But I can run a simple session using my Edirol UA-25 USB soundcard with 
8ms of system latency.

> I would like to use both. (one portable studio and one upstairs)
>

That's possible, you're best choice would be USB then assuming not all 
your machines have a FireWire connection.

Best,

Jeremy