[LAT] To much latency

[Dave Stikkolorum]

On 30-10-11 13:03, Jeremy Jongepier wrote:
> 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!

cat /proc/asound/card*/codec* | grep -i codec

Codec: Analog Devices AD1984A
Codec: LSI ID 1040



>
>> 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
>
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