[wdmaudiodev] Re: - How to capture HDMI audio output data? Whether is sAPO a choice for it?

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Fri, 21 Oct 2011 09:54:44 -0700

Jun Jiang wrote:
> Thank you very much. Your solution gave me big help. The loopback
> capture works well to capture HDMI audio output data.

This may be picking at details, but it bothers me.  You should stop
thinking about this as "HDMI audio output data".  HDMI is a video cable
standard that happens to include audio signals.  The data you are
capturing has nothing to do with your audio hardware.  You are capturing
the current audio output stream.  Whether it goes to an HD audio board,
or a USB audio board, or an old Creative Labs sound card is not
relevant.  You are capturing your main audio output stream.

> I play a song and ran slience.exe as your suggesion but there was
> still AUDCLNT_BUFFERFLAGS_DATA_DISCONTINUITY happened sometimes just
> like following cases in your blog:
> ... IAudioCaptureClient::GetBuffer set flags to 0x00000001 on pass
> 5381 after 1088829 frames...
> Could you please show me some suggstion on it?

It could be something as simple as a slight clocking mismatch.  My guess
is that it is not important.  Do you get that more than once?

> I have another question: How much delay will be added for loopback
> capture?

The latency varies based on system configuration..  It is something you
will probably have to measure yourself, and you may need to do it each
time you start up your algorithm.

Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.

Other related posts: