[wdmaudiodev] Re: AC3 over SPDIF -using WDM
- From: "Vargheese Baby" <vargheese.baby@xxxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Wed, 14 Jun 2006 20:56:40 +0530
Devendra,
I could resolve the issue which I was facing. Let me explain the scenario.
Earlier I was using VLC for AC3 play back. It is having AC3 decoder with it
; thus it convert AC3 to PCM and downstream to my driver. But my driver gets
the AC3 tag(0x92) and gets the stream through AC3 pin since it announce its
capability to play AC3 data.
I got two methods to resolve the issue.
1. Use a media player with AC3 pass through option ( I used PowerDVD)
2. Use an AC3 filter with AC3 pass through option.
By any of these I could get an AC3 pass through to my driver.
Now the issue has resolved.
The volume and mute buttons of my PowerDVD gets disabled as soon as I select
the SPDIF option. Could anyone tell about how can we control volume in case
of AC3 over SPDIF?
Thanks and Regards
Varghese
_____
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of BlazeAudio Developer
Sent: Wednesday, June 14, 2006 11:18 AM
To: wdmaudiodev@xxxxxxxxxxxxx; wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: AC3 over SPDIF -using WDM
Vargheese,
I do not understand your first point 2. (you have two point number 2s).
You say that it is a PCM wave output, not AC3 passthrough. Do you mean to sa
that VLC is decoding the AC-3 to PCM, doing a downmix to 2 channel PCM, and
sending you the 2 channel PCM?
Which pin is being instantiated - the PCM or AC3 pin? What's the data format
that comes along when VLC plays the AC-3 file?
Thanks.
Devendra.
At 06:19 PM 6/8/2006, Vargheese Baby wrote:
Hello Devendra,
I am using the sample driver comes along "Windows Server 2003 DDK" and
installed it on Windows XP. I need to develop a virtual driver with ac3
support using this. (Instead of sending the audio data to sound card I need
to send it to user space application). This driver implementation satisfies
all the steps given by the Microsoft article for Non PCM data format. But it
always gives a PCM wave corresponding to AC3.
The following things I observed with this driver.
1. The driver gives a PCM wave output(through the PCM pin of driver) while
playing an MP3 song using WinAmp\WMP\VLC. - It is the required behavior
2. While palying an AC3 file with VLC, the driver identify the non PCM
format and declare it is having non PCM support. And it delivers the stream
through the non-PCM pin of driver; but it is a PCM wave output(No AC3
passthough)
2. I installed a AC3 filter( got a free download from net) and set a option
AC3 passthrogh. The result is same. The only difference is I could play an
AC3 song using WMP earlier it could not.
By this could we make out some assumptions?
Regards
Vargheese
_____
From: wdmaudiodev-bounce@xxxxxxxxxxxxx [
<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx>
mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of BlazeAudio Developer
Sent: Thursday, June 08, 2006 2:31 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: AC3 over SPDIF -using WDM
Vargheese,
What applications are you trying to use to test sending an AC3 stream?
Different DVD players require this to be configured differently.
You might also want to verify that your pin is exposing the data ranges
correctly by examining the filter in KSStudio, and trying to instantiate the
AC-3 pin with a proper data format corresponding to AC3/SPDIF.
Thanks.
Devendra.
At 09:11 AM 6/8/2006, Vargheese Baby wrote:
Hello
I am using DDK sample driver [MSVAD\AC3] for achieving ac3 over SPDIF. But
my miniport driver gets a PCM streams converted from AC3 always. The sample
driver uses a wavecyclic port with AC3 pins. Its topology filter does not
have any AC3 pins\nodes (Microsoft document also recommend like this).
Any way to get AC3 pass through with this driver? Should I additionally use
any AC3 filter with SPDIF passthrough option to achieve this?
Anybody could give a solution please?
Thanks and Regards
Vargheese
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