On Fri, 22 Feb 2008, Florian wrote: >> But the laptop is not running realtime linux is it? It has > sure it is... > >> loads of potential latencies and stuff demanding the system's >> attention-- page swapping, program swapping, etc. So why would >> you think that it would work on Linux without underruns? If >> you wnat 1ms latencies, your computer must be feading the >> beast at least every .1ms with no interruptions longer than >> 1ms. That is not many samples in your buffer. I have no idea >> if alsa can be made to work that way. > > basically we have that setup working on a workstation, so why > shouldn't it work on a laptop? Actually, my collegues here > "think" in guaranteed time slices in the microsecond or even > nanosecond range. For them, 1 millisecond is an eternity where A > LOT can be done on modern processors :) I agree with that. OK, so you are saying that you believe that the software side is under control-- from the system on up, and you want to know if there exists a card which itself on the hardware side does not itself introduce latencies in the msec range. I suspect few have tested the cards that way, so it may be up to you to do so. As I said I have liked the maudio transit (it is cheap, usb, and has very good sound reproduction) but I certainly have never tested its latency. Not sure how you would do so, since your ear certainly cannot hear time differences on the level of msec. More like 100ms. I suppose you could measure it-- eg a loopback with sound out going right back into the intput, -- or even setting up a feedback loop and seeing what freq it howls at. Never tried it. > > Later, > Florian > >>> >>> Thanks, Florian >>> >>> >>> >>> On 2/22/2008 1:48 AM, Bill Unruh wrote: >>>> On Fri, 22 Feb 2008, Florian wrote: >>>> >>>>> Hi, >>>>> >>>>> on our IBM/Lenovo T60 laptop, we want higher audio >>>>> quality than the built-in HD-Audio, especially low >>>>> latency - in the range of 1 millisecond or lower. >>>>> >>>>> Can anyone recommend a PCCard/Cardbus soundcard, or >>>>> possibly a USB card supported by alsa and which you've >>>>> been able to run with low latency? >>>> >>>> The usb audio maudio transit I have been quite pleased by, >>>> esp now that the alsa has stabilised for this card. >>>> Latency it sseems to me is more a matter of the buffer >>>> size that is used than anything else. At 1ms you can only >>>> have at most 20 samples in the buffer. That runs the >>>> danger of underruns, since something could distract the >>>> computer for that length of time. >>>> >>>> >>>>> >>>>> Thanks, Florian >>>>> >>>>> >>>>> >>>> >>> >>> >> > > -- William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324 UBC, Vancouver,BC | Program in Cosmology | unruh@xxxxxxxxxxxxxx Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/ ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
