---
title: StartIO
framework: audiodriverkit
role: symbol
role_heading: Instance Method
path: audiodriverkit/iouseraudiostream/startio
---

# StartIO

Tells the stream to start I/O.

## Declaration

```occ
virtual kern_return_t StartIO(IOUserAudioStartStopFlags in_flags);
```

## Parameters

- `in_flags`: A IOUserAudioStartStopFlag to indicate I/O startup behavior.

## Return Value

Return Value kIOReturnSuccess on success, or another value if an error occurs. For a list of error codes, see Error Codes.

## Discussion

Discussion The default implementation always returns kIOReturnSuccess. Subclass and override this method to handle hardware-specific tasks during I/O startup, then call the superclass to update the I/O state. The framework expects this call to always succeed or fail. The hardware can take as long as it needs in this call, provided it always either succeeds or fails.

## See Also

### Performing I/O

- [StopIO](audiodriverkit/iouseraudiostream/stopio.md)
- [IOUserAudioStartStopFlags](audiodriverkit/audiodriverkit/iouseraudiostartstopflags.md)