# Sample Attachment Keys Keys that specify attachments to individual samples in a buffer. ## Discussion You can get and set sample-level attachments in a sample buffer using the [`CMSampleBufferGetSampleAttachmentsArray(_:createIfNecessary:)`](/documentation/CoreMedia/CMSampleBufferGetSampleAttachmentsArray(_:createIfNecessary:)) function. ## Topics ### Sample Keys [`kCMSampleAttachmentKey_NotSync`](/documentation/CoreMedia/kCMSampleAttachmentKey_NotSync) Indicates whether the sample is a sync sample (type `CFBoolean`, default false). [`kCMSampleAttachmentKey_PartialSync`](/documentation/CoreMedia/kCMSampleAttachmentKey_PartialSync) Indicates whether the sample is a partial sync sample (type `CFBoolean`, default false). [`kCMSampleAttachmentKey_DependsOnOthers`](/documentation/CoreMedia/kCMSampleAttachmentKey_DependsOnOthers) Indicates whether the sample depends on other samples for decoding (type `CFBoolean`). [`kCMSampleAttachmentKey_IsDependedOnByOthers`](/documentation/CoreMedia/kCMSampleAttachmentKey_IsDependedOnByOthers) Indicates whether other samples depend on this sample for decoding (type `CFBoolean`). [`kCMSampleAttachmentKey_DisplayImmediately`](/documentation/CoreMedia/kCMSampleAttachmentKey_DisplayImmediately) Indicates whether the sample should be displayed immediately (type `CFBoolean`, default false). [`kCMSampleAttachmentKey_DoNotDisplay`](/documentation/CoreMedia/kCMSampleAttachmentKey_DoNotDisplay) Indicates whether the sample should be decoded but not displayed (type `CFBoolean`, default false). [`kCMSampleAttachmentKey_EarlierDisplayTimesAllowed`](/documentation/CoreMedia/kCMSampleAttachmentKey_EarlierDisplayTimesAllowed) Indicates whether later samples may have earlier display times (type `CFBoolean`). [`kCMSampleAttachmentKey_HasRedundantCoding`](/documentation/CoreMedia/kCMSampleAttachmentKey_HasRedundantCoding) Indicates whether the sample has redundant coding (type `CFBoolean`). [`kCMSampleAttachmentKey_PostDecodeProcessingMetadata`](/documentation/CoreMedia/kCMSampleAttachmentKey_PostDecodeProcessingMetadata) ### Sample Buffer Keys [`kCMSampleBufferAttachmentKey_DisplayEmptyMediaImmediately`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_DisplayEmptyMediaImmediately) Tells that the empty marker should be dequeued immediately regardless of its timestamp (type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_DrainAfterDecoding`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_DrainAfterDecoding) Indicates whether the sample buffer should be drained after decoding type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_DroppedFrameReason`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_DroppedFrameReason) Indicates the reason the current video frame was dropped (type `CFString`). [`kCMSampleBufferDroppedFrameReason_FrameWasLate`](/documentation/CoreMedia/kCMSampleBufferDroppedFrameReason_FrameWasLate) The frame was dropped because it was late. [`kCMSampleBufferDroppedFrameReason_OutOfBuffers`](/documentation/CoreMedia/kCMSampleBufferDroppedFrameReason_OutOfBuffers) The frame was dropped because the module providing frames is out of buffers. [`kCMSampleBufferDroppedFrameReason_Discontinuity`](/documentation/CoreMedia/kCMSampleBufferDroppedFrameReason_Discontinuity) An unknown number of frames were dropped. [`kCMSampleBufferAttachmentKey_DroppedFrameReasonInfo`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_DroppedFrameReasonInfo) Indicates additional information regarding the dropped video frame (type `CFString`). [`kCMSampleBufferDroppedFrameReasonInfo_CameraModeSwitch`](/documentation/CoreMedia/kCMSampleBufferDroppedFrameReasonInfo_CameraModeSwitch) A discontinuity was caused by a camera mode switch. [`kCMSampleBufferAttachmentKey_EmptyMedia`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_EmptyMedia) Marks an intentionally empty interval in the sequence of samples (type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_EndsPreviousSampleDuration`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_EndsPreviousSampleDuration) Indicates that sample buffer’s decode timestamp may be used to define the previous sample buffer’s duration (type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_FillDiscontinuitiesWithSilence`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_FillDiscontinuitiesWithSilence) Fill the difference between discontiguous sample buffers with silence (type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_ForceKeyFrame`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_ForceKeyFrame) Indicates that the current or next video sample buffer should be forced to be encoded as a key frame. [`kCMSampleBufferAttachmentKey_GradualDecoderRefresh`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_GradualDecoderRefresh) Indicates the decoder refresh count (type `CFNumber`). [`kCMSampleBufferAttachmentKey_PermanentEmptyMedia`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_PermanentEmptyMedia) Marks the end of the sequence of samples (type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_PostNotificationWhenConsumed`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_PostNotificationWhenConsumed) If present, indicates that decode pipelines should post a notification when consuming the sample buffer(type `CFDictionary`). [`kCMSampleBufferAttachmentKey_ResetDecoderBeforeDecoding`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_ResetDecoderBeforeDecoding) Indicates whether the sample buffer should be reset before decoding (type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_ResumeOutput`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_ResumeOutput) If present, indicates that output should be resumed following a discontinuity `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_Reverse`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_Reverse) Indicates that the decoded contents of the sample buffer should be reversed (type `CFBoolean`, default false). [`kCMSampleBufferAttachmentKey_SampleReferenceByteOffset`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_SampleReferenceByteOffset) Indicates the byte offset at which the sample data begins (type `CFNumber`). [`kCMSampleBufferAttachmentKey_SampleReferenceURL`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_SampleReferenceURL) Indicates the URL where the sample data is (type `CFURL`). [`kCMSampleBufferAttachmentKey_SpeedMultiplier`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_SpeedMultiplier) The factor by which the sample buffer’s presentation should be accelerated (type `CFNumber`, default 1.0). [`kCMSampleBufferAttachmentKey_StillImageLensStabilizationInfo`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_StillImageLensStabilizationInfo) Indicates information about the lens stabilization applied to the current still image buffer. [`kCMSampleBufferLensStabilizationInfo_Active`](/documentation/CoreMedia/kCMSampleBufferLensStabilizationInfo_Active) The lens stabilization module was active for the duration this buffer. [`kCMSampleBufferLensStabilizationInfo_OutOfRange`](/documentation/CoreMedia/kCMSampleBufferLensStabilizationInfo_OutOfRange) The motion of the device or duration of the capture was outside of what the stabilization mechanism could support. [`kCMSampleBufferLensStabilizationInfo_Unavailable`](/documentation/CoreMedia/kCMSampleBufferLensStabilizationInfo_Unavailable) The lens stabilization module was unavailable for use. [`kCMSampleBufferLensStabilizationInfo_Off`](/documentation/CoreMedia/kCMSampleBufferLensStabilizationInfo_Off) The lens stabilization module was not used during this capture. [`kCMSampleBufferAttachmentKey_TransitionID`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_TransitionID) Marks a transition from one source of buffers to another. [`kCMSampleBufferAttachmentKey_TrimDurationAtEnd`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_TrimDurationAtEnd) The duration that should be removed at the end of the sample buffer, after decoding. [`kCMSampleBufferAttachmentKey_TrimDurationAtStart`](/documentation/CoreMedia/kCMSampleBufferAttachmentKey_TrimDurationAtStart) The duration that should be removed at the beginning of the sample buffer, after decoding. --- Copyright © 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)