[wdmaudiodev] Re: Naive beginner with only a concept: front filter to use a VST plugin.
- From: "Mike Kemp" <mjk@xxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Thu, 9 May 2013 08:26:20 +0100
>The overarching mantra in the redesign of the Audio Engine in Vista was
>efficiency and low latency. <
>Microsoft has made it difficult to insert arbitrary helpful "filters" in the
>audio path, because... <
I thought it was DRC: i.e. make it impossible to intercept digital audio
between the codec and the analogue output (or encrypted digital output like
HDMI/HDCP) to prevent copying.
I discarded an idea a few years ago to intercept digital audio to feed to an
application (for rescheduling streaming radio programmes) on the understanding
that MS were continuing to make interception of the digital audio stream
increasingly difficult. If that was a correct understanding, even if a way to
get into that data path is available now, it may be closed off in future
Windows updates...
Mike
----- Original Message -----
From: Tim Roberts
To: wdmaudiodev@xxxxxxxxxxxxx
Sent: Wednesday, May 08, 2013 6:57 PM
Subject: [wdmaudiodev] Re: Naive beginner with only a concept: front filter
to use a VST plugin.
Don Gateley wrote:
>
> My reason for wanting a driver/device interface is not to do any low
> level kernel processing but simply to give a user a familiar way to
> direct output to a DSP filter via the "Windows Sound" control panel
> and to configure the plugin and real output device via it. Is there a
> path to such a driver interface that doesn't involve kernel mode
> (other than perhaps as a hidden bridge)? I clearly misdirected my
> query. Can you suggest a forum or list more appropriate?
I don't think you misdirected your query at all. The people who would
know how to do this live on this list.
One issue is that you're up against a philosophy problem. The
overarching mantra in the redesign of the Audio Engine in Vista was
efficiency and low latency. On a system with an HDAudio device (which
is most systems these days), audio traffic never passes through kernel
mode at all. The Audio Engine process writes directly to the board's
audio buffers.
Microsoft has made it difficult to insert arbitrary helpful "filters" in
the audio path, because that makes the path non-deterministic for
high-performance audio applications. What you are doing here is counter
to that trend. Instead of app to audio engine to device, you'll now
have app to kernel interceptor to user-mode VST host to VST graph to
audio engine to device. That's a lot of players.
I'm not saying this is impossible, just that this is a somewhat bigger
problem than you may realize. I see your concept, and I think it could
be made to work, but it's a big job.
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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