MultiSourceMediaFrameReader.TryAcquireLatestFrame Method
Definition
Important
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Attempts to obtain a MultiSourceMediaFrameReference object which provides access to the latest time-correlated frames from one or more MediaFrameSource objects.
public:
virtual MultiSourceMediaFrameReference ^ TryAcquireLatestFrame() = TryAcquireLatestFrame;MultiSourceMediaFrameReference TryAcquireLatestFrame();public MultiSourceMediaFrameReference TryAcquireLatestFrame();function tryAcquireLatestFrame()Public Function TryAcquireLatestFrame () As MultiSourceMediaFrameReferenceReturns
A MultiSourceMediaFrameReference providing access to the latest frames from the media frame sources.
Remarks
After getting an instance of MultiSourceMediaFrameReference, get the time-correlated media frame from a particular media frame source by calling MultiSourceMediaFrameReference.TryGetFrameReferenceBySourceId and passing in the value of the MediaFrameSourceInfo.Id property for the desired media frame source.
Each MultiSourceMediaFrameReader maintains a circular buffer of MediaFrameReference objects obtained from TryAcquireLatestFrame. After all of the MediaFrameReference objects in the buffer have been used, subsequent calls to TryAcquireLatestFrame will cause the system to call Close (or Dispose in C#) on the oldest buffer object in order to reuse it. Once the object has been disposed, you can no longer use it to access the frame data. For this reason, you should not store the MediaFrameReference object longer than you actually need to process the frame. If your app scenario requires you to keep a reference to the data for longer, you should use one of the APIs provided to get the underlying data. These methods include:
- BufferMediaFrame.Buffer
- VideoMediaFrame.SoftwareBitmap
- VideoMediaFrame.GetVideoFrame
- VideoMediaFrame.CameraIntrinsics
It is the responsibility of the app to call Close (or Dispose) on the objects returned by these APIs when they are no longer being used.
Important
If you access the SoftwareBitmap or Direct3DSurface objects provided by the VideoMediaFrame property of a MediaFrameReference, the system creates a strong reference to these objects, which means that they will not be disposed when you call Dispose on the containing MediaFrameReference. You must explicitly call the Dispose method of the SoftwareBitmap or Direct3DSurface directly for the objects to be immediately disposed. Otherwise, the garbage collector will eventually free the memory for these objects, but you can't know when this will occur, and if the number of allocated bitmaps or surfaces exceeds the maximum amount allowed by the system, the flow of new frames will stop.