public static extern PAErrorCode Pa_OpenDefaultStream(out IntPtr stream, int numInputChannels, int numOutputChannels, uint sampleFormat, double sampleRate, uint framesPerBuffer, StreamCallbackDelegate streamCallback, IntPtr userData);
public static extern PAErrorCode Pa_OpenStream(out IntPtr stream, ref PAStreamParameters inputParameters, IntPtr outputParameters, double sampleRate, uint framesPerBuffer, PAStreamFlags streamFlags, StreamCallbackDelegate streamCallback, IntPtr userData);