[wdmaudiodev] Re: AW: DirectSound and XXDVD Strange behavior

  • From: david lee <davidlioncity@xxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Mon, 18 Oct 2004 09:11:06 +0800 (CST)

Dear Nick,
Yes, I do agree with what you said. Okay, It is better to  give an example to 
clarify the situation what I met. Basically, I get one SPDIF package, for 
example, 6144bytes for AC3 data, by call GetMapping. However, by following 
GetMapping call, I get all zero data and there is no any SPDIF header for these 
data. Thus:
1) These data are sent by Applications. But it looks like impossible because 
all data sent by application will be packaged, which means that I will get 
SPDIF Header.
2) DSound insert these data. But I really cannot understand why DSound will 
insert these data. According to DDK documents, if portclass do not have enough 
data send to miniport driver, it will
repeat the buffer which it holds. Therefore, I should not get all these zero
data while the repeated buffer.
BTW Can any application guys or Microsfot guys give comments?

Nick Gorohov <engkosha2001@xxxxxxxxx> wrote:
Dear David!

I am Audio Filter designer at Sonic ( www.sonic.com ).
Yes, we do that with SPDIF: the beginning is real portion
of the spdif data ( the real amount is in data header),
the rest filled with 0's. The trick is that a whole pack
of data has the same number of audiosamples that
unencrypted ( PCM ) pack will have. So, can ignore all
these 0's.


Nick Gorokhov 

--- david lee wrote:

> Dear Stephan,
> In fact, I set theConnectionInterface.Id =NULL, then what is the default
> value.
> According to what you say, as long as I update the position, the port class
> will send more valid data to me. Am I correct?
> Thanks
> Stephan Kappertz wrote:
> You should check the pins ConnectionInterface.Id when the pin is created.
> Most likely the ConnectionInterface is KSINTERFACE_STANDARD_LOOPED_STREAMING.
> This means that your driver receives just one valid circular buffer when
> playback starts. It is supposed to loop through this buffer until playback
> stops. The current DMA position that your driver reports will be used to
> update the portion of the circular buffer with new data that is currently NOT
> played. 
> Stephan 
> -----Ursprüngliche Nachricht-----
> Von: wdmaudiodev-bounce@xxxxxxxxxxxxx
> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] Im Auftrag von david lee
> Gesendet: Monday, October 11, 2004 11:35 AM
> An: wdmaudiodev@xxxxxxxxxxxxx
> Betreff: [wdmaudiodev] DirectSound and PowerDVD/WinDVD Strange behavior
> Dear all,
> When I use PowerDVD/WinDVD SPDIF pass through and select direct sound audio
> render, I always get a lot of zero data with a few valid data in the
> beginning of playback. Due to use driver to decode the AC3/DTS data, I am not
> sure how to handle these zero data. Any suggestion? (Treat them as data need
> to be decoded or as rubbish and discarded)
> BTW, if I select waveout audio render, All the data at the beginning are
> useful valid data,which I can decode.
> Thanks in advance
> David 
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