Tells the delegate that a new sample sequence is commencing.
- iOS 6.0+
- macOS 10.8+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
The output object that sent the message.
This method is called after any attempt to seek or change the playback direction of the item’s content. If you are maintaining any queued future samples, you can use your implementation of this method to discard those samples.