---
title: kCMSampleAttachmentKey_NotSync
framework: coremedia
role: symbol
role_heading: Global Variable
path: coremedia/kcmsampleattachmentkey_notsync
---

# kCMSampleAttachmentKey_NotSync

Indicates whether the sample is a sync sample (type CFBoolean, default false).

## Declaration

```swift
let kCMSampleAttachmentKey_NotSync: CFString
```

## Discussion

Discussion A sync sample, also known as a key frame or IDR (Instantaneous Decoding Refresh), can be decoded without requiring any previous samples to have been decoded. Samples following a sync sample also do not require samples prior to the sync sample to have been decoded. Samples are assumed to be sync samples by default — set the value for this key to kCFBooleanTrue for samples which should not be treated as sync samples. This attachment is read from and written to media files.

## See Also

### Sample Keys

- [kCMSampleAttachmentKey_PartialSync](coremedia/kcmsampleattachmentkey_partialsync.md)
- [kCMSampleAttachmentKey_DependsOnOthers](coremedia/kcmsampleattachmentkey_dependsonothers.md)
- [kCMSampleAttachmentKey_IsDependedOnByOthers](coremedia/kcmsampleattachmentkey_isdependedonbyothers.md)
- [kCMSampleAttachmentKey_DisplayImmediately](coremedia/kcmsampleattachmentkey_displayimmediately.md)
- [kCMSampleAttachmentKey_DoNotDisplay](coremedia/kcmsampleattachmentkey_donotdisplay.md)
- [kCMSampleAttachmentKey_EarlierDisplayTimesAllowed](coremedia/kcmsampleattachmentkey_earlierdisplaytimesallowed.md)
- [kCMSampleAttachmentKey_HasRedundantCoding](coremedia/kcmsampleattachmentkey_hasredundantcoding.md)
- [kCMSampleAttachmentKey_PostDecodeProcessingMetadata](coremedia/kcmsampleattachmentkey_postdecodeprocessingmetadata.md)