Hello wdmaudiodev!
I am developing an APO Driver, specifically an "LFX" APO (I need to be
compatible with Win7). The key points of this APO are:
-
- I am using WDK 10.1.17.110
- My APO is registered with APO_FLAG_FRAMESPERSECOND_MUST_MATCH |
APO_FLAG_BITSPERSAMPLE_MUST_MATCH
- DSP processing of multiple channels in to produce 2 out.
- I make calls to a DSP library which runs at 44.1k or 48k
- The USB heaphone I am targetting runs at 96k
I am finding unusual behaviours in relation to IsInputFormatSupported()
compared to what I have read in the MS documentation. Simply put, I have
implemented IsInputFormatSupported() as follows:
- I return S_FALSE if the input channel count is not what I suuprt, and
I suggest 2
- I return S_FALSE if the input sample rate is not 44.1k or 48k, and I
suggest 48k
According to the documentation, given that my output format is 96k, I would
expect to be presented with 96k to start with and then, after I reject that
and suggest 48k I would expect to be offered 48k, which I would accept and
then we'd all happily move to LockForProcess().
However, what I am finding (on my Win 10 PC) is that Windows repeatedly
offers me 96k and then, after I reject it, gives up, disabling my APO.
I have 2 questions:
1. Does anyone have any tips or observations on my scenario as described
above
2. I override IsOutputFormatSupported() in my APO but note that it is
never called - is this expected and, if so, can I just get rid of the
overrride?
Thanks!
Culann
