> 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.
the beauty (and the whole idea of using real-time audio for showcasing realtime systems) is that you WILL hear if there is an i/o problem anywhere in the path from user app to hardware: even 4 samples "missing" (i.e. an underrun) will cause a very sharp transient in the outgoing signal, which is audible as a click. You can try that with any ALSA app that lets you set the buffer size to arbitrary values. And, as you suggest, the signal's frequency spectrum will contain very high frequencies, so we've created a tool to automatically detect underruns from the recorded audio output of the soundcard, (and to correlate that with the underruns reported by ALSA). Later, Florian > 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 >>>>>> >>>>>> >>>>>> >>>>> >>>> >>>> >>> >> >> > -- Florian Bomers Bome Software ------------------------------------------------------- Music Software, Development Tools: http://www.bome.com Java Sound extensions, plugins: http://www.tritonus.org The Java Sound Resources: http://www.jsresources.org ------------------------------------------------------- Please quote this email in your reply. Thanks! ------------------------------------------------------------------------- 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@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
