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# kVTCompressionPropertyKey_MoreFramesBeforeStart

A Boolean value that indicates whether and how a compression session concatenates frames with other compressed frames to form a longer series.

```
let kVTCompressionPropertyKey_MoreFramesBeforeStart: CFString
```

## Discussion

This value is `true` if frames compressed in a separate session will be concatenated before the beginning of the current session. The value is `false` if the current session is a stand-alone session, or if this session will encode the first segment of a multi-segment compression. The default value is `false`.

This information enables video encoders to ensure that compressed segments can be concatenated smoothly – for example, avoiding data rate spikes where segments are joined.

---

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