[wdmaudiodev] Re: Normalized samples in Vista/Win 7 LFX/GFX

  • From: "Jose Catena" <jc1@xxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Sat, 1 May 2010 18:20:32 +0200

Quick answer: samples sent to the final renderer should not ever exceed the
-1...+1 range. Otherwise distortion may occur.
The more complex answer: behavior depends on the drivers downstream. In
theory they may allow values larger than nominal range and may contain fixed
or variable gain stages to correct improper input levels. There are a few
cases of pro audio hardware that do so. But in most cases samples outside of
-1...+1 are clipped.

Jose Catena
DIGIWAVES S.L.

Michael R. Preston wrote:
> I'm curious if anyone has the answer to this...  If the LFX of an APO 
> outputs samples that are outside the normal -1.0 -> 1.0 range, does this 
> cause any problems - even if the GFX ensures the audio is scaled back 
> down to the normal range in the end?  Is there some tolerance in the 
> Windows audio code for an LFX outputting samples that are slightly 
> outside the normal range, or is -1.0 -> 1.0 a hard limit?
> 
> Thanks,
> Mike Preston


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