[wdmaudiodev] Re: Question about APO and multichannel inputs

  • From: Arunasree_Swapna@xxxxxxxxxxxx
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Mon, 3 Aug 2009 09:53:53 -0700

I am faced with a similar problem with an LFX APO we have.
Why is the behavior different for different players and how do we use the
API  IsInputFormatSupported() and IsOutputFormatSupported() correctly, so
we can do the right thing?
Any code snippets?


Arunasree Swapna
Software Engineer
360-514-5760 (office)

             "Cheng-mean Liu                 <wdmaudiodev@xxxxxxxxxxxxx>
             (SOCCER)"                                                  cc
                                             [wdmaudiodev] Re: Question
                                             about APO and multichannel
             Sent by:                        inputs                    
             08/03/2009 09:47 AM                                       
                Please respond to                                      

When  running  with  different  players,  are you seeing different behavior
(call    parameters,    return    code)   in   your   APO's   handling   of

From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of
Sent: Monday, August 03, 2009 5:46 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Question about APO and multichannel inputs

Hi All,

I  am  developing  a  LFX APO to implement a stereo headphone with surround
effect. The APO includes a multi-channel to stereo virtualizer. The APO can
accept  both  stereo  input  and  multi-channel  input  and  output  stereo
virtualized  sound.  Now,  we  are  testing  our APO. If the test player is
Windows  Media player, the APO works fine. We can try a 2-channel songs and
then  a  6-channel music. The APO input channel number is changing with the
file content which is playing by WMP.

But,  it is not the case of other players. When we use WinAmp as player and
play a stereo music file and then drag a 6 channel file to play. The result
is  we  can  not  see  any  format change action in APO side. And the input
format  remain  unchanged  2  channel.  The 6 channel file is down mixed to
2-channel  to  be  received  by  APO.  Since  APO  did  not  get  the exact
multi-channel data, the virtualized result is not what we desired.

I tried another player; it has the same behaviors as WinAmp.

Does any one know why it happens?

Why WMP can void this problem?

I   am   trying   to   fix  the  input  format  to  6-channel(   by  change
IsInputFormatSupported() and IsOutputFormatSupported() ), but failed. Is it

Thanks in advance.

                    Software                                          Dept.
                    VIA      Technologies      (China)      Inc.,      Ltd.
                    E-mail:                          MikeLee@xxxxxxxxxxxxxx
                    Tele: 86-010-59852288 ext.3830

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