Re: low-latency audio I/O for Windows (Satrajit Ghosh )


Subject: Re: low-latency audio I/O for Windows
From:    Satrajit Ghosh  <satrajit.ghosh@xxxxxxxx>
Date:    Thu, 4 Oct 2007 00:20:01 -0400
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

We have used the M-Audio Delta 44 in ASIO mode with measured input to output latency being approximately 5ms at 48KHz sampling rate. I believe this can be brought down further (perhaps to less than 4ms) using the 96KHz sampling rate. Cheers, satra -- Satrajit Ghosh Research Scientist Speech Communications Group Research Lab of Electronics @xxxxxxxx MIT On 10/3/07, Kelly Fitz <kelly_fitz@xxxxxxxx> wrote: > I believe that RME still makes the lowest latency sound cards, but that > they do not really approach the latency you require. The Hammerfall > claims 1.5ms, but that is not throughput latency, it is the hardware > latency. For simulating hearing aid algorithms, you need to pay that > twice, once going in, and once going out. > > Moreover, most audio APIs that I know of use some kind of buffering, and > you will therefore have those latencies on top of the sound card > hardware latency. Other software systems like Max or Pd may impose > additional buffering latencies. > > I am told that at the last IHCON, Giso Grimm (University of Oldenburg) > demonstrated a system that achieved latency as low as 7ms, using a linux > PC with ASIO drivers and the Hammerfall card. I think the system itself > is described in > > Giso Grimm, Tobias Herzke, Daniel Berg, and Volker Hohmann. The Master > Hearing Aid – a pc-based platform for algorithm development and > evaluation. Accepted 2006 Acustica united with acta acustica, April 2006. > > I have never heard of a low-latency USB or 1394 interface, and I don't > know enough about those protocols to know whether it is even achievable, > but it is a reasonable question to ask. The low-latency RME cards are > PCI or cardbus. > > If anyone can come up with a PC-and-soundcard-based system that has > reliable and demonstrable <4 ms throughput latency, I'd love to know > about it. > > HTH, > Kelly > > Freed, Dan wrote: > > Dear Auditory List Members: > > > > I'm looking for a low-latency audio interface device for use with > > Windows computers. The goal is to perform real-time signal processing > > on the PC for the purpose of developing and testing hearing aid DSP > > algorithms. Consequently I need to keep the hardware-related signal > > delay to a minimum. > > > > Unfortunately, manufacturers generally don't include latency in their > > specifications, and tech support and sales people don't seem to have > > latency information either. So I'm hoping that people on this list can > > point me at some acceptable devices. > > > > My target is a total input-to-PC-to-output delay <= 3 ms at 48 kHz. I'd > > prefer an external device (USB or FireWire). Other desirable features > > include a mic input, a headphone output, analog I/O level controls, and > > support for a wide range of sampling rates (16, 24, and 32 kHz would be > > nice). But the critical feature is the low latency; I can work around > > other limitations. > > > > Any suggestions will be greatly appreciated. Thank you! > > > > Dan Freed > > Senior Engineer > > Dept. of Human Communication Sciences & Devices > > House Ear Institute > > 2100 W. Third St. > > Los Angeles, CA 90057 USA > > Phone: +1-213-353-7084 > > Fax: +1-213-413-0950 > > Email: dfreed@xxxxxxxx > > > > -- > Kelly Fitz, DSP Research Engineer > Starkey Hearing Research Center >


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