Re: [linux-audio-user] Re: linux audio interface

From: Cesare Marilungo <cesare@email-addr-hidden>
Date: Fri May 05 2006 - 20:00:03 EEST

In fact I don't think you can achieve lower latency with an USB card.

Anyway if you play a softsynth (like the great ZynAddSubFx, or Om) with
a midi keyboard, the sum of the latency of the softsynth (that you can
adjust by setting the buffer size) plus the interface ->out latency
(~3ms with the UA-25), you'll have the same or even less delay (from
pressing the key to hearing the sound) that you'll get on an hardware
digital synth (6-8ms, AFAIK).

When you need to record an external source you can also use the direct
monitor (available on the UA-25).

cezar@email-addr-hidden wrote:

>I have 8ms on M-Audio FW 410 on windows, and It's ok ! for playin keys
>
>So the Ediroll board sounds ok (I guess) being portable also
>
>Florian Paul Schmidt <mista.tapas@email-addr-hidden> writes:
>
>
>
>>On Fri, 05 May 2006 00:51:49 +0000
>>Cesare Marilungo <cesare@email-addr-hidden> wrote:
>>
>>
>>
>>>>6. MIDI is necessary and also lowest latency possible. (which I don't know
>>>> what it is on linux)
>>>>
>>>>
>>>I'm really happy with my Edirol UA-25.
>>>
>>>http://www.roland.com/products/en/_support/dld.cfm?ln=en&dsp=0&iCncd=526
>>>
>>>Latency could be set as low as 5.8ms (2.9ms in +2.9ms out) if the CPU
>>>load of the session your're working on is not too heavy.
>>>
>>>
>>Just as a sidenote: On a -rt system, which is properly setup (irq and
>>app priorities) and a delta 44/66/1010 you can use periodsizes down to 8
>>frames. 8 frames at a samplerate of 48000 corresponds to a (roundtrip)
>>latency of
>>
>>2 * (8/48000) = 0.0003333. sec = 0.3333... ms
>>
>>While context switching overhead gets really huge it is in principle
>>possible to get ridicously low latency (you really don't want to use a
>>periodsize of 8 frames though. Even jack idle load is around 20-30% with
>>that setting -> ugh).
>>
>>Operation with 32 or 64 frames per period is possible without problems
>>at all.
>>
>>I don't think this is possible with USB hardware, and i have no idea
>>whether it's possible with firewire hardware.
>>
>>The delta card i use is a PCI card and i suppose in principle the same
>>should be possible with a pcmcia card (which is afaik just a pci bus in
>>disguise).
>>
>>Have fun,
>>Flo
>>
>>--
>>Palimm Palimm!
>>http://tapas.affenbande.org
>>
>>
>
>
>
>
>
c.

-- 
www.cesaremarilungo.com
Received on Fri May 5 20:15:02 2006

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