[wdmaudiodev] Re: Where is the latency in the USB audio stack ?
- From: "Jerry J. Trantow" <Jerry.Trantow@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 19 Apr 2004 10:26:56 -0500
Why not go asio? I've worked with Markus Medau at
http://www.usb-audio.com/
He provides very low latency asio usb drivers for the Sound Device USBPre as
well as other products. His driver was designed for asio but also functions
as a Windows audio device.
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry Evans
Sent: Monday, April 19, 2004 10:14 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Where is the latency in the USB audio stack ?
Hi all.
We have some custom input only hardware running over USB 1 at 6 * 16 * 48K.
Most happily the stock WinXP SP1 USB audio driver works properly when
accessed in KS mode from our own user-mode app(s). The downside of this
arrangement is that we need to sync 2 KS devices to enable low-latency
playback. Measurements indicate that having 2 USB devices plugged into a
single USB 2 hub (theoretically optimal configuration) gives us a minimum
practical latency of ~45 ms. This leads me onto the core issue: Given that
there is at least 10ms latency in the USB audio stack (as posted by DJS
sometime last year in this list) we were wondering if a suitable USB driver
could be made to supplant the stock USB stack, i.e. the user could opt to
install the high performance driver. Question is how much of a win we might
get: is the latency all in usbaudio.sys or is it further down the stack ?
We'd be most happy if we could get the overall latency down below 20ms. Any
tips would be greatly appreciated.
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