LowLagPhotoSequenceCapture class

Applies to Windows and Windows Phone

Provides methods for taking a rapid sequence of low shutter lag photos.

Syntax


/* For information about creating or accessing this object, see Remarks. */

Attributes

[DualApiPartition()]
[MarshalingBehavior(Standard)]
[Threading(MTA)]
[Version(0x06030000)]

Members

The LowLagPhotoSequenceCapture class has these types of members:

Events

The LowLagPhotoSequenceCapture class has these events.

EventDescription
PhotoCaptured Occurs when a photo has been captured.

 

Methods

The LowLagPhotoSequenceCapture class has these methods. With C#, Visual Basic, and C++, it also inherits methods from the Object class.

MethodDescription
FinishAsync Asynchronously releases the LowLagPhotoSequenceCapture object and resources used by the photo sequence capture operation.
StartAsync Asynchronously starts capturing photos.
StopAsync Asynchronously stops capturing photos.

 

Remarks

Photo sequence mode takes a rapid sequence of photos. A key scenario for photo sequence is getting photos in the past, that is prior to when the user takes a photo.

You can access the LowLagPhotoSequenceControl for the capture device through MediaCapture.VideoDeviceController. LowLagPhotoSequenceControl is used to manage settings related to the photo sequence session.

You can find out if the device supports photo sequence mode by checking LowLagPhotoSequenceControl.Supported.

Use MediaCapture.PrepareLowLagPhotoSequenceCaptureAsync to initialize the photo sequence capture. This is an asynchronous call which returns a LowLagPhotoSequenceCapture object when it is finished. This must be called before StartAsync.

To start capturing photos, call StartAsync. The app will continue to receive photos from the device until the operation is stopped.

StopAsync stops the operation, which can be restarted with StartAsync.

Add a handler to the PhotoCaptured event in order to get the captured photos in the sequence. PhotoCapturedEventArgs provides the data for the captured frames. PhotoCapturedEventArgs.Frame contains the captured photo and PhotoCapturedEventArgs.Thumbnail contains the thumbnail.

FinishAsync stops the photo sequence capture operation and releases the LowLagPhotoSequenceCapture object and resources used by the photo sequence operation. If you want to restart the photo sequence operation after calling FinishAsync, you must call MediaCapture.PrepareLowLagPhotoSequenceCaptureAsync to initialize a new LowLagPhotoSequenceCapture object.

If the media type is changed or an effect is added, you must call MediaCapture.PrepareLowLagPhotoSequenceCaptureAsync to create a new LowLagPhotoCapture object.

LowLagPhotoSequenceControl.GetCurrentFrameRate specifies the frame rate at which the photos are taken.

PhotoCapturedEventArgs.CaptureTimeOffset can be used to tell whether a frame was in the future, greater than 0, or in the past, less than 0.

If the app wants to limit how many frames it gets per second, it can use LowLagPhotoSequenceControl.PhotosPerSecondLimit. This can be useful in situations where the sensor on the device can handle 30fps, but the app only needs 4fps.

To enable thumbnails, set LowLagPhotoSequenceControl.ThumbnailEnabled to true.

You can set the desired thumbnail size through LowLagPhotoSequenceControl.DesiredThumbnailSize and set the thumbnail format through LowLagPhotoSequenceControl.ThumbnailFormat.

The number of past photos cannot be more than LowLagPhotoSequenceControl.MaxPastPhotos, which is the maximum number of past photos that is supported by the driver. The number of past photos returned will be the smaller of the following values: LowLagPhotoSequenceControl.PastPhotoLimit, LowLagPhotoSequenceControl.MaxPastPhotos, or the current number of available past photos.

Requirements

Minimum supported client

Windows 8.1 [Windows Store apps, desktop apps]

Minimum supported server

Windows Server 2012 R2 [Windows Store apps, desktop apps]

Minimum supported phone

Windows Phone 8.1 [Windows Phone Silverlight 8.1 and Windows Runtime apps]

Namespace

Windows.Media.Capture
Windows::Media::Capture [C++]

Metadata

Windows.winmd

See also

Object
MediaCapture.PrepareLowLagPhotoSequenceCaptureAsync
LowLagPhotoSequenceControl
MediaControl.VideoDeviceController
LowLagPhotoCapture

 

 

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