Custom Audio Effects in Windows Vista Custom Audio Effects in Windows Vista

How to Implement a Custom sAPO

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  An sAPO can have one input and one output connection. This connection is an audio buffer and can be multichannel.
  
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  An sAPO must be real-time compatible. This means:
  
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  All buffers that are processed by the sAPO must be nonpageable.
  
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  All code and data in the process path must be nonpageable.
  
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  All methods that are members of real-time interfaces must be implemented as nonblocking. They should not block, use paged memory, or call any blocking system routines. Note that most system routines are blocking. Real-time interfaces are identified by an “RT” at the end of their name, such as IAudioProcessingObjectRT.
  
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  Real-time compatible sAPOs can be used in contexts that do not require real-time processing.
  
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  An sAPO can modify only the audio data that is passed to it through its IAudioProcessingObjectRT::APOProcess routine. It cannot change the settings of the underlying logical device, including its KS topology.
  
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  GFX sAPOs must process data by using a format with a fixed frame size. The frame size is specified by the advertised supported format. The format is static for both input and output.
  
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  GFX sAPOs should avoid introducing more than 10 ms of latency into the audio processing chain. An sAPO reports this latency through the IAudioProcessingObject::GetLatency API.