Gets the current position of the sources associated with this playing ID, obtained from PostEvent(). Notes:
You need to pass AK_EnableGetSourcePlayPosition to PostEvent() in order to use this function, otherwise it returns AK_Fail, even if the playing ID is valid.
The source's position is updated at every audio frame, and the time at which this occurs is stored. When you call this function from your thread, you therefore query the position that was updated in the previous audio frame. If in_bExtrapolate is true (default), the returned position is extrapolated using the elapsed time since last sound engine update and the source's playback rate.
If 0 is passed in for the number of entries (*in_pcPositions == 0) then only the number of positions will be returned and the position array (out_puPositions) will not be updated.
The io_pcPositions pointer must be non-NULL. out_puPositions may be NULL if *io_pcPositions == 0, otherwise it must be non-NULL.
AK_Success if successful.
AK_InvalidParameter if the provided pointer is not valid.
AK_PlayingIDNotFound if the playing ID is invalid (not playing yet, or finished playing).