[wdmaudiodev] 答复: Re: Question about APO and multichannel inputs

  • From: <MikeLee@xxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Tue, 4 Aug 2009 11:00:56 +0800

None functions in APO, such as IsInputFormatSupported(), is called when the 
media is changing from 2ch to 6ch file by using WinAmp. From APO side, we can 
not detect any actions. 

But it is very strange that when we play 6ch file first and then the 2ch file. 
APO can be correctly informed and a format negotiate process will be perform by 
IsInputFormatSupported() and IsOutputFormatSupported(). It is hard to explain.

BTW, WinAmp is using DSound plug-in to output sound. It is OK when we just play 
2ch file or just play 6ch file and then close the WinAmp.





发件人: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] 
代表 Cheng-mean Liu (SOCCER)
发送时间: 2009年8月4日 0:47
收件人: wdmaudiodev@xxxxxxxxxxxxx
主题: [wdmaudiodev] Re: Question about APO and multichannel inputs


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



From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of MikeLee@xxxxxxxxxxxxxx
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 


Other related posts:

  • » [wdmaudiodev] 答复: Re: Question about APO and multichannel inputs - MikeLee