Utility Functions
In addition to the functions described elsewhere in this tutorial, PortAudio provides a number of Utility functions which are useful in a variety of circumstances. You'll want to see the portaudio.h Doxygen page, which documents the entire V19 API for details, but we'll try to cover the basics here.
Version Information
PortAudio offers two functions to determine the PortAudio Version. This is most useful when you are using PortAudio as a dynamic library, but it may also be useful at other times.
int Pa_GetVersion (void) const char * Pa_GetVersionText (void)
Error Text
PortAudio allows you to get error text from an error number.
const char * Pa_GetErrorText (PaError errorCode)
Stream State
PortAudio Streams exist in 3 states: Active, Stopped, and Callback Stopped. If a stream is in callback stopped state, you'll need to stop it before you can start it again. If you need to query the state of a PortAudio stream, there are two functions for doing so:
PaError Pa_IsStreamStopped (PaStream *stream) PaError Pa_IsStreamActive (PaStream *stream)
Stream Info
If you need to retrieve info about a given stream, such as latency, and sample rate info, there's a function for that too:
const PaStreamInfo * Pa_GetStreamInfo (PaStream *stream)
Stream Time and CPU Usage
To determine how long the stream has been running or How much CPU is being used by the callback, use these:
PaTime Pa_GetStreamTime (PaStream *stream) double Pa_GetStreamCpuLoad (PaStream *stream)
Other utilities
These functions allow you to determine the size of a sample from its format and sleep for a given amount of time. The sleep function should not be used for precise timing or synchronization because it makes few guarantees about the exact length of time it waits. It is most useful for testing.
PaError Pa_GetSampleSize (PaSampleFormat format) void Pa_Sleep (long msec)
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