[wdmaudiodev] Re: One Audio Driver Problem

  • From: æåæ <huengpei@xxxxxxxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Sat, 29 Jan 2005 23:38:45 +0800

Dear Sam Tertzakian:

>> When you say âserious delayâ do you mean that the audio is out of sync 
>> with the video?

Yes, this is my problem.



>> One of the filters use KxProxy which uses very small buffers. That is 
>> probably the one that works well.


>> The other filter uses the WaveAPI and uses big buffers. 

>> So what happens is that the video starts playing immediately while it takes 
>> a short time for audio buffer to fill up.

You mean that the filter within "Audio Capture Sources" folder which is based 
on WaveAPI filter, right?

 

>> If you are capturing audio/video to a file, it should not be a problem as 
>> both streams are time stamped. But if you are previewing audio/video, then 
>> it can be a problem >> to use the WaveAPI filter since the WaveAPI buffers 
>> are so large. And, you cannot time stamp the audio/video preview stream 
>> because then the video renderer will >> cause the video to start and stop. 
>> If you are using GraphEdit to build the graph, there is no solution (that I 
>> know of). But, if you write a program using direct show

>> (basically doing the same thing as GraphEdit), you can use the WaveAPI 
>> filter and you change the buffer size that it uses in the program. 

But, why the preview problem can't be happened for these USB Audio Class 
device. 

I can use the filter well (Just using GraphEdit only).



>> I have done this before and it works greatâbut, right now I cannot 
>> remember the exact details. If you need to know, let me know and I will post 
>> the information. From >> what I remember, there is no sample in the DDK that 
>> shows this. But the functions are documented somewhereâI just cannot 
>> remember the com interface name right >> nowâ I may have posted an answer 
>> similar to this in this forum, but I am not sure.

Dear Sam Tertzakian, Thank you very much. ^______________^

Can you get me more information about the problem?



Best Regards,

H.P.

  ----- Original Message ----- 
  From: Sam Tertzakian 
  To: wdmaudiodev@xxxxxxxxxxxxx 
  Sent: Saturday, January 29, 2005 11:16 PM
  Subject: [wdmaudiodev] Re: One Audio Driver Problem


  When you say âserious delayâ do you mean that the audio is out of sync 
with the video?

   

  One of the filters use KxProxy which uses very small buffers. That is 
probably the one that works well.

   

  The other filter uses the WaveAPI and uses big buffers. So what happens is 
that the video starts playing immediately while it takes a short time for audio 
buffer to fill up.

   

  If you are capturing audio/video to a file, it should not be a problem as 
both streams are time stamped. But if you are previewing audio/video, then it 
can be a problem to use the WaveAPI filter since the WaveAPI buffers are so 
large. And, you cannot time stamp the audio/video preview stream because then 
the video renderer will cause the video to start and stop.

   

  If you are using GraphEdit to build the graph, there is no solution (that I 
know of). But, if you write a program using direct show (basically doing the 
same thing as GraphEdit), you can use the WaveAPI filter and you change the 
buffer size that it uses in the program. I have done this before and it works 
greatâbut, right now I cannot remember the exact details. If you need to 
know, let me know and I will post the information. From what I remember, there 
is no sample in the DDK that shows this. But the functions are documented 
somewhereâI just cannot remember the com interface name right nowâ

   

  I may have posted an answer similar to this in this forum, but I am not sure.


------------------------------------------------------------------------------

  From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of ???
  Sent: Saturday, January 29, 2005 7:01 AM
  To: wdmaudiodev@xxxxxxxxxxxxx
  Subject: [wdmaudiodev] One Audio Driver Problem

   

  Dear All:

   

  I am developing an audio driver which is based on Streaming Minidriver 
framework.

  When I use the filter within "WDM Streaming Capture Devices" category, the 
audio stream (44100MHz) is listened well.

  However, when I use the filter of "Audio Capture Sources" folder, there is a 
serious delay (1 ~ 2 secs) which is happened.

  I don't know what's happened in this delay.

  The filter within "Audio Capture Sources" folder is a virtual filter, right?

  Why can't the MasterClock be offered from DirectShow manager for this filter?

  Can you help me to solve this problem?

   

  Best Regards,

  H.P.

   

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