peek_audio_format
Description:
Gets a CallAudioFormat object specifying the audio format used by the audio port if call audio is routed via the host.
Warning: 
      
        
    
    The returned value is only valid until the property changes so it is only safe to use this function on the thread where this was constructed. Use get_audio_format if on another thread.
Parameters:
| this | A Call. | 
Returns:
| A CallAudioFormat. Do not free the returned value, it belongs to this. |