---
title: mStartOffset
framework: coreaudiotypes
role: symbol
role_heading: Instance Property
path: coreaudiotypes/audiostreampacketdescription/mstartoffset
---

# mStartOffset

The number of bytes from the start of the buffer to the beginning of the packet.

## Declaration

```swift
var mStartOffset: Int64
```

## Discussion

Discussion For example, if the data buffer contains 5 bytes of data, with one byte per packet, then the start offset for the last packet is 4. There are 4 bytes in the buffer before the start of the last packet.

## See Also

### Inspecting an audio stream packet description

- [mDataByteSize](coreaudiotypes/audiostreampacketdescription/mdatabytesize.md)
- [mVariableFramesInPacket](coreaudiotypes/audiostreampacketdescription/mvariableframesinpacket.md)