[wdmaudiodev] Question about APO and multichannel inputs

  • From: <MikeLee@xxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Mon, 3 Aug 2009 20:45:42 +0800

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 possible?


Thanks in advance.


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


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