---
title: "fileOutput(_:didStartRecordingTo:startPTS:from:)"
framework: avfoundation
role: symbol
role_heading: Instance Method
path: "avfoundation/avcapturefileoutputrecordingdelegate/fileoutput(_:didstartrecordingto:startpts:from:)"
---

# fileOutput(_:didStartRecordingTo:startPTS:from:)

## Declaration

```swift
optional func fileOutput(_ output: AVCaptureFileOutput, didStartRecordingTo fileURL: URL, startPTS: CMTime, from connections: [AVCaptureConnection])
```

## Parameters

- `output`: The capture file output that started writing the file.
- `fileURL`: The file URL of the file that is being written.
- `startPTS`: The timestamp of the first buffer written to the file, synced with AVCaptureSession.synchronizationClock
- `connections`: An array of AVCaptureConnection objects attached to the file output that provided the data that is being written to the file.

## Discussion

Discussion Informs the delegate when the output has started writing to a file. This method is called when the file output has started writing data to a file. If an error condition prevents any data from being written, this method may not be called. captureOutput:willFinishRecordingToOutputFileAtURL:fromConnections:error: and captureOutput:didFinishRecordingToOutputFileAtURL:fromConnections:error: will always be called, even if no data is written. If this method is implemented, the alternative delegate callback -captureOutput:didStartRecordingToOutputFileAtURL:fromConnections will not be called. Clients should not assume that this method will be called on a specific thread, and should also try to make this method as efficient as possible.

## See Also

### Delegate methods

- [fileOutput(_:didStartRecordingTo:from:)](avfoundation/avcapturefileoutputrecordingdelegate/fileoutput(_:didstartrecordingto:from:).md)
- [fileOutput(_:willFinishRecordingTo:from:error:)](avfoundation/avcapturefileoutputrecordingdelegate/fileoutput(_:willfinishrecordingto:from:error:).md)
- [fileOutput(_:didFinishRecordingTo:from:error:)](avfoundation/avcapturefileoutputrecordingdelegate/fileoutput(_:didfinishrecordingto:from:error:).md)
- [fileOutput(_:didPauseRecordingTo:from:)](avfoundation/avcapturefileoutputrecordingdelegate/fileoutput(_:didpauserecordingto:from:).md)
- [fileOutput(_:didResumeRecordingTo:from:)](avfoundation/avcapturefileoutputrecordingdelegate/fileoutput(_:didresumerecordingto:from:).md)