[wdmaudiodev] Re: Asynchronous input and output
- From: "Jeff Pages" <barefeet@xxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 8 May 2006 22:25:06 +1000
Hi Hauke,
Yes, if the input and output rates are set the same then you'd expect them
to be synchronised, and my own experience with applications that pass input
through to output is that that is the case, at least with the sound cards
we've used. I'm wondering if you might be experiencing buffer underruns. Are
you using multiple buffers, and are your buffers large enough to cover
latencies in the system?
Jeff
----- Original Message -----
From: "Audiodev" <audiodev@xxxxxxxxxxxxxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Monday, May 08, 2006 10:04 PM
Subject: [wdmaudiodev] Re: Asynchronous input and output
Hi Jeff,
thank you for the response. I have understood that with sample rate
conversion in XP I wont find the
exact right sample rate, e.g. 31995 instead of 32000 Hz.
What I still do not understand is why there is a difference in samplerates
between input and output even if both have been setup for the same rate.
If both directions apply the same rate conversion the rates should also be
identical, not exactly at the right sample rate but at
least equal. Are input and output treated in different ways?
Is there a sample rate that demands no rate conversion, maybe the maximum
rate available?
Is there a way that an application finds this "native" sample rate in
kernel streaming?
In that case there should be no drift for the maximum samplerate...
Best Regards,
Hauke
Jeff Pages wrote:
The sampling rate converter in Windows XP and earlier appears to round
all conversion ratios to the nearest factor of 160. For example 44.1/48
is 147/160, which is exact, but 32/48 is rounded to 107/160 which is a
little bit off. This is really annoying, but it looks like it's been
fixed in Vista.
Jeff Pages
Innes Corporation Pty Ltd
----- Original Message ----- From: "Audiodev"
<audiodev@xxxxxxxxxxxxxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Friday, May 05, 2006 6:02 PM
Subject: [wdmaudiodev] Asynchronous input and output
Hello Community,
I have a question which one of the driver developers who read this EMail
may be able to answer.
We have measured with directX and kernel Streaming that with the same
audio device the input and the output
run at different samplerates. The difference is rather small, approx.
less than 10 Hz in most cases but it exists.
I would expect this behavior when using two devices but not for one
device and especially when using kernel streaming.
From my point of view soundcards should have one chip for AD/DA
conversion running at one fixed clock.
What is the reason that an application has to deal with this problem?
Best Regards,
Hauke
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