Latency in Audio

Karl MacMillan karlmac at
Fri Mar 2 04:15:40 CET 2001


You are not going to do very well trying to get better results out of
Windows ME / 2000 until PD supports something like ASIO.  Even then, I
don't think that the results are going to be that good.  In some tests
that I did recently the best full-duplex performance I could get out of
Windows ME was 73ms and Windows 2000 was 120ms - this was using a minimal
'ideal' application with the MME interface.  This was on a 700mhz PIII and
a 933mhz PIII respectively.

Many companies have been advertising much better results under Windows and
I have to say it seems that either a) these results represent something
other than real world performance or b) the app runs almost entirely as a
kernel driver (gigasampler being the best example of this).  If you really
want good latency you should try Linux or Irix.  For the same test that I
mentioned above I got latencies below 3ms using Linux 2.4.1 and Alsa -
this is using standard programming interfaces and the same computer as the
Windows 2000 test.  If you have to use windows, I would suggest
downgrading to windows 98 as it is slightly better.


> Hi,
>        I've some problems with the latency in PD's Audio in/out.
>     I use PD under Windows ME and Win2000 and works very well (in Win2K midi timing is more stable), but I've some problems to use it for my works in real time. I must use it for very little patch (filtering, ring modulation ...), but the latency is about 300ms.
>     I run it on a Athlon Th. 800 Mhz, 256 Ram, HD IBM 30Gb, audioCard SBLive.
>     How can I reduce the latency? I will buy a Terratec 24/96, so I hope to reduce the latency time.
>     Can someone give me some councils?
> With my best regards
> Claudio Scozzafava

| Karl W. MacMillan                                 |
| Computer Music Department                         |
| Peabody Institute of the Johns Hopkins University |
| karlmac at                           |
|                      |

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