<!--
{
  "availability" : [
    "iOS: 2.0.0 -",
    "iPadOS: 2.0.0 -",
    "macCatalyst: 13.0.0 -",
    "macOS: 10.2.0 -",
    "tvOS: 9.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 3.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "CoreAudioTypes",
  "identifier" : "/documentation/CoreAudioTypes/AudioStreamPacketDescription/mStartOffset",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "Core Audio Types"
    ],
    "preciseIdentifier" : "c:@S@AudioStreamPacketDescription@FI@mStartOffset"
  },
  "title" : "mStartOffset"
}
-->

# mStartOffset

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

```
var mStartOffset: Int64
```

## 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.

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)