# AVSampleCursor An object that provides information about the media sample at the cursor’s current position. ``` class AVSampleCursor ``` ## Overview You position a sample cursor at a specific media sample in a sequence of samples contained in a higher-level object, like an [`AVAssetTrack`](/documentation/AVFoundation/AVAssetTrack). You can move it to a new position in that sequence either backwards or forwards, either in decode order or in presentation order. You can also request moving it according to a count of samples or a delta in time. Use a sample cursor to get information about the media sample such as its duration, timestamps, dependency information, and so on. You can also use them to synchronously to perform I/O in order to load media data of one or more media samples into memory. ## Topics ### Navigating samples [`step(byDecodeTime:wasPinned:)`](/documentation/AVFoundation/AVSampleCursor/step(byDecodeTime:wasPinned:)) Moves the cursor by a given delta time on the decode timeline. [`step(byPresentationTime:wasPinned:)`](/documentation/AVFoundation/AVSampleCursor/step(byPresentationTime:wasPinned:)) Moves the cursor by a given delta time on the presentation timeline. [`stepInDecodeOrder(byCount:)`](/documentation/AVFoundation/AVSampleCursor/stepInDecodeOrder(byCount:)) Moves the cursor a given number of samples in decode order. [`stepInPresentationOrder(byCount:)`](/documentation/AVFoundation/AVSampleCursor/stepInPresentationOrder(byCount:)) Moves the cursor a given number of samples in presentation order. ### Getting timestamps [`decodeTimeStamp`](/documentation/AVFoundation/AVSampleCursor/decodeTimeStamp) The decode timestamp of the sample at the current position of the cursor. [`presentationTimeStamp`](/documentation/AVFoundation/AVSampleCursor/presentationTimeStamp) The presentation timestamp of the sample at the current position of the cursor. ### Getting sample information [`currentChunkInfo`](/documentation/AVFoundation/AVSampleCursor/currentChunkInfo) A value that provides information about the chunk of samples to which the current sample belongs. [`AVSampleCursorChunkInfo`](/documentation/AVFoundation/AVSampleCursorChunkInfo) A value that provides information about a chunk of media samples. [`currentChunkStorageRange`](/documentation/AVFoundation/AVSampleCursor/currentChunkStorageRange) The sample range in the storage container to load together with the current sample as a chunk. [`AVSampleCursorStorageRange`](/documentation/AVFoundation/AVSampleCursorStorageRange) A structure that indicates the offset and length of storage for a media sample or its chunk. [`currentChunkStorageURL`](/documentation/AVFoundation/AVSampleCursor/currentChunkStorageURL) The URL of the storage container of the current sample and other samples to load in the same operation as a chunk. [`currentSampleDependencyInfo`](/documentation/AVFoundation/AVSampleCursor/currentSampleDependencyInfo) The dependency information that describes relationships between a media sample and other media samples in the same sample sequence. [`AVSampleCursorDependencyInfo`](/documentation/AVFoundation/AVSampleCursorDependencyInfo) A value for describing dependencies between a media sample and other media samples in the same sample sequence. [`currentSampleDuration`](/documentation/AVFoundation/AVSampleCursor/currentSampleDuration) The decode duration of the sample at the cursor’s current position. [`currentSampleIndexInChunk`](/documentation/AVFoundation/AVSampleCursor/currentSampleIndexInChunk) The index of the current sample within the chunk to which it belongs. [`currentSampleStorageRange`](/documentation/AVFoundation/AVSampleCursor/currentSampleStorageRange) The offset and length of the current sample in the current chunk storage URL. [`currentSampleSyncInfo`](/documentation/AVFoundation/AVSampleCursor/currentSampleSyncInfo) The synchronization information for the current sample for consideration when resynchronizing a decoder. [`AVSampleCursorSyncInfo`](/documentation/AVFoundation/AVSampleCursorSyncInfo) A structure that describes the attributes of media samples to consider when resynchronizing a decoder. [`copyCurrentSampleFormatDescription()`](/documentation/AVFoundation/AVSampleCursor/copyCurrentSampleFormatDescription()) Returns the format description of the sample at the cursor’s current position. [`currentSampleAudioDependencyInfo`](/documentation/AVFoundation/AVSampleCursor/currentSampleAudioDependencyInfo) The independent decodability information for the audio sample. [`currentSampleDependencyAttachments`](/documentation/AVFoundation/AVSampleCursor/currentSampleDependencyAttachments) A dictionary of dependency-related sample buffer attachments. ### Accessing samples [`maySamplesWithEarlierDecodeTimeStampsHavePresentationTimeStamps(laterThan:)`](/documentation/AVFoundation/AVSampleCursor/maySamplesWithEarlierDecodeTimeStampsHavePresentationTimeStamps(laterThan:)) Determines whether a sample earlier in decode order can have a presentation timestamp later than that of the specified sample cursor. [`maySamplesWithLaterDecodeTimeStampsHavePresentationTimeStamps(earlierThan:)`](/documentation/AVFoundation/AVSampleCursor/maySamplesWithLaterDecodeTimeStampsHavePresentationTimeStamps(earlierThan:)) Determines whether a sample later in decode order can have a presentation timestamp earlier than that of the specified sample cursor. [`samplesRequiredForDecoderRefresh`](/documentation/AVFoundation/AVSampleCursor/samplesRequiredForDecoderRefresh) The number of samples prior to the current sample, in decode order, the decoder requires to achieve a coherent output at the current decode time. ### Comparing sample cursors [`comparePositionInDecodeOrder(withPositionOf:)`](/documentation/AVFoundation/AVSampleCursor/comparePositionInDecodeOrder(withPositionOf:)) Compares the relative positions of two sample cursors and returns their relative positions. --- 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)