---
title: expectsMediaDataInRealTime
framework: avfoundation
role: symbol
role_heading: Instance Property
path: avfoundation/avassetwriterinput/expectsmediadatainrealtime
---

# expectsMediaDataInRealTime

A Boolean value that indicates whether the input tailors its processing for real-time sources.

## Declaration

```swift
var expectsMediaDataInRealTime: Bool { get set }
```

## Discussion

Discussion Set this value to true if your app appends media data to the input from a real-time source, such as an AVCaptureOutput. Setting a true value optimizes the input for real-time usage so it accurately calculates the state of its isReadyForMoreMediaData property value. You can’t set this value after writing starts. important: To ensure optimal behavior, don’t set the value of this property and performsMultiPassEncodingIfSupported to true at the same time.

## See Also

### Appending media samples

- [isReadyForMoreMediaData](avfoundation/avassetwriterinput/isreadyformoremediadata.md)
- [requestMediaDataWhenReady(on:using:)](avfoundation/avassetwriterinput/requestmediadatawhenready(on:using:).md)
- [append(_:)](avfoundation/avassetwriterinput/append(_:).md)
- [markAsFinished()](avfoundation/avassetwriterinput/markasfinished().md)
- [AVAssetWriterInput.SampleBufferReceiver](avfoundation/avassetwriterinput/samplebufferreceiver.md)
- [AVAssetWriterInput.PixelBufferReceiver](avfoundation/avassetwriterinput/pixelbufferreceiver.md)
- [AVAssetWriterInput.TaggedPixelBufferGroupReceiver](avfoundation/avassetwriterinput/taggedpixelbuffergroupreceiver.md)
- [AVAssetWriterInput.MetadataReceiver](avfoundation/avassetwriterinput/metadatareceiver.md)
- [AVAssetWriterInput.CaptionReceiver](avfoundation/avassetwriterinput/captionreceiver.md)