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# VTFrameSiloCallFunctionForEachSampleBuffer(_:in:refcon:callback:)

Retrieves sample buffers from a frame silo object.

```
func VTFrameSiloCallFunctionForEachSampleBuffer(_ silo: VTFrameSilo, in timeRange: CMTimeRange, refcon: UnsafeMutableRawPointer?, callback: (UnsafeMutableRawPointer?, CMSampleBuffer) -> OSStatus) -> OSStatus
```

## Parameters

`silo`

The frame silo object.

`timeRange`

The decode time range of the sample buffers to retrieve. Pass `kCMTimeRangeInvalid` to retrieve all sample buffers from the `VTFrameSilo.`

`refcon`

A reference value.

`callback`

A function to be called, in decode order, with each sample buffer that was added. To abort iteration early, return a nonzero status. The `VTFrameSilo` object may write sample buffers and data to the backing file between addition and retrieval;  do not expect to get identical object pointers back.

## Return Value

`kVTFrameSiloInvalidTimeRangeErr` if any time ranges are non-numeric, overlap, or are not in ascending order. Returns any nonzero status returned by the callback function.

## Discussion

You call this function to retrieve sample buffers at the end of a multipass compression session.

---

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