Andy De George
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title, ms.date, helpviewer_keywords, ms.assetid
| title | ms.date | helpviewer_keywords | ms.assetid | ||
|---|---|---|---|---|---|
| Multimedia Overview | 03/30/2017 |
|
feb25b15-d741-4ac3-818f-1b19f63a3562 |
Multimedia Overview
The multimedia features in [!INCLUDETLA#tla_winclient] enable you to integrate audio and video into your applications to enhance the user experience. This topic introduces the multimedia features of [!INCLUDETLA2#tla_winclient].
Media API
The xref:System.Windows.Controls.MediaElement and xref:System.Windows.Media.MediaPlayer classes are used to present audio or video content. These classes can be controlled interactively or by a clock. These classes can use on the Microsoft Windows Media Player 10 control for media playback. Which class you use, depends on the scenario.
xref:System.Windows.Controls.MediaElement is a xref:System.Windows.UIElement that is supported by the Layout and can be consumed as the content of many controls. It is also usable in [!INCLUDETLA#tla_xaml] as well as code. xref:System.Windows.Media.MediaPlayer, on the other hand, is designed for xref:System.Windows.Media.Drawing objects and lacks layout support. Media loaded using a xref:System.Windows.Media.MediaPlayer can only be presented using a xref:System.Windows.Media.VideoDrawing or by directly interacting with a xref:System.Windows.Media.DrawingContext. xref:System.Windows.Media.MediaPlayer cannot be used in XAML.
For more information about drawing objects and drawing context, see Drawing Objects Overview.
Note
When distributing media with your application, you cannot use a media file as a project resource. In your project file, you must instead set the media type to
Contentand setCopyToOutputDirectorytoPreserveNewestorAlways.
Media Playback Modes
Note
Both xref:System.Windows.Controls.MediaElement and xref:System.Windows.Media.MediaPlayer have similar members. The links in this section refer to the xref:System.Windows.Controls.MediaElement class members. Unless specifically noted, members linked to in the xref:System.Windows.Controls.MediaElement class can also be found in the xref:System.Windows.Media.MediaPlayer class.
To understand media playback in [!INCLUDETLA#tla_winclient], an understanding of the different modes in which media can be played is required. Both xref:System.Windows.Controls.MediaElement and xref:System.Windows.Media.MediaPlayer can be used in two different media modes, independent mode and clock mode. The media mode is determined by the xref:System.Windows.Controls.MediaElement.Clock%2A property. When xref:System.Windows.Controls.MediaElement.Clock%2A is null, the media object is in independent mode. When the xref:System.Windows.Controls.MediaElement.Clock%2A is non-null, the media object is in clock mode. By default, media objects are in independent mode.
Independent Mode
In independent mode, the media content drives media playback. Independent mode enables the following options:
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Media's xref:System.Uri can be directly specified.
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Media playback can be directly controlled.
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Media's xref:System.Windows.Controls.MediaElement.Position%2A and xref:System.Windows.Controls.MediaElement.SpeedRatio%2A properties can be modified.
Media is loaded by either setting the xref:System.Windows.Controls.MediaElement object's xref:System.Windows.Controls.MediaElement.Source%2A property or by calling the xref:System.Windows.Media.MediaPlayer object's xref:System.Windows.Media.MediaPlayer.Open%2A method.
To control media playback in independent mode, the media object's control methods can be used. The control methods available are xref:System.Windows.Controls.MediaElement.Play%2A, xref:System.Windows.Controls.MediaElement.Pause%2A, xref:System.Windows.Controls.MediaElement.Close%2A, and xref:System.Windows.Controls.MediaElement.Stop%2A. For xref:System.Windows.Controls.MediaElement, interactive control using these methods is only available when the xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A is set to xref:System.Windows.Controls.MediaState.Manual. These methods are unavailable when the media object is in clock mode.
See Control a MediaElement (Play, Pause, Stop, Volume, and Speed) for an example of independent mode.
Clock Mode
In clock mode, a xref:System.Windows.Media.MediaTimeline drives media playback. Clock mode has the following characteristics:
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Media's xref:System.Uri is indirectly set through a xref:System.Windows.Media.MediaTimeline.
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Media playback can be controlled by the clock. The media object's control methods cannot be used.
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Media is loaded by setting a xref:System.Windows.Media.MediaTimeline object's xref:System.Windows.Media.MediaTimeline.Source%2A property, creating the clock from the timeline, and assigning the clock to the media object. Media is also loaded this way when a xref:System.Windows.Media.MediaTimeline inside a xref:System.Windows.Media.Animation.Storyboard targets a xref:System.Windows.Controls.MediaElement.
To control media playback in clock mode, the xref:System.Windows.Media.Animation.ClockController control methods must be used. A xref:System.Windows.Media.Animation.ClockController is obtained from the xref:System.Windows.Media.Animation.ClockController property of the xref:System.Windows.Media.MediaClock. If you attempt to use the control methods of either a xref:System.Windows.Controls.MediaElement or xref:System.Windows.Media.MediaPlayer object while in clock mode, an xref:System.InvalidOperationException will be thrown.
See the Animation Overview for more information about clocks and timelines.
See Control a MediaElement by Using a Storyboard for an example of clock mode.
MediaElement Class
Adding media to an application is as simple as adding a xref:System.Windows.Controls.MediaElement control to the [!INCLUDETLA#tla_ui] of the application and providing a xref:System.Uri to the media you wish to include. All media types supported by Microsoft Windows Media Player 10 are supported in [!INCLUDETLA#tla_winclient]. The following example shows a simple usage of the xref:System.Windows.Controls.MediaElement in [!INCLUDETLA#tla_xaml].
[!code-xamlMediaElement_snip#SimpleMediaElementUsageWholePage]
In this sample, media is played automatically as soon as it is loaded. Once the media has finished playing, the media is closed and all media resources are release (including video memory). This is the default behavior of the xref:System.Windows.Controls.MediaElement object and is controlled by the xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A and xref:System.Windows.Controls.MediaElement.UnloadedBehavior%2A properties.
Controlling a MediaElement
The xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A and xref:System.Windows.Controls.MediaElement.UnloadedBehavior%2A properties control the behavior of the xref:System.Windows.Controls.MediaElement when xref:System.Windows.FrameworkElement.IsLoaded%2A is true or false, respectively. The xref:System.Windows.Controls.MediaState the properties are set to affect the media playback behavior. For example, the default xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A is xref:System.Windows.Controls.MediaState.Play and the default xref:System.Windows.Controls.MediaElement.UnloadedBehavior%2A is xref:System.Windows.Controls.MediaState.Close. This means that as soon as the xref:System.Windows.Controls.MediaElement is loaded and the preroll is complete, the media begins to play. Once playback is complete, media is closed and all media resources are released.
The xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A and xref:System.Windows.Controls.MediaElement.UnloadedBehavior%2A properties are not the only way to control media playback. In clock mode, the clock can control the xref:System.Windows.Controls.MediaElement and the interactive control methods have control when the xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A is xref:System.Windows.Controls.MediaState.Manual. xref:System.Windows.Controls.MediaElement handles this competition for control by evaluating the following priorities.
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xref:System.Windows.Controls.MediaElement.UnloadedBehavior%2A. In place when media is unloaded. This ensures that all media resources are released by default, even when a xref:System.Windows.Media.MediaClock is associated with the xref:System.Windows.Controls.MediaElement.
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xref:System.Windows.Media.MediaClock. In place when media has a xref:System.Windows.Controls.MediaElement.Clock%2A. If media is unloaded, the xref:System.Windows.Media.MediaClock will take effect as long as the xref:System.Windows.Controls.MediaElement.UnloadedBehavior%2A is xref:System.Windows.Controls.MediaState.Manual. Clock mode always overrides the loaded behavior of the xref:System.Windows.Controls.MediaElement.
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xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A. In place when media is loaded.
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Interactive control methods. In place when xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A is xref:System.Windows.Controls.MediaState.Manual. The control methods available are xref:System.Windows.Controls.MediaElement.Play%2A, xref:System.Windows.Controls.MediaElement.Pause%2A, xref:System.Windows.Controls.MediaElement.Close%2A, and xref:System.Windows.Controls.MediaElement.Stop%2A.
Displaying a MediaElement
To display a xref:System.Windows.Controls.MediaElement it must have content to render and it will have its xref:System.Windows.FrameworkElement.ActualWidth%2A and xref:System.Windows.FrameworkElement.ActualHeight%2A properties set to zero until content is loaded. For audio only content, these properties are always zero. For video content, once the xref:System.Windows.Controls.MediaElement.MediaOpened event has been raised the xref:System.Windows.FrameworkElement.ActualWidth%2A and xref:System.Windows.FrameworkElement.ActualHeight%2A will report the size of the loaded media. This means that until media is loaded, the xref:System.Windows.Controls.MediaElement will not take up any physical space in the [!INCLUDETLA#tla_ui] unless the xref:System.Windows.FrameworkElement.Width%2A or xref:System.Windows.FrameworkElement.Height%2A properties are set.
Setting both the xref:System.Windows.FrameworkElement.Width%2A and xref:System.Windows.FrameworkElement.Height%2A properties will cause the media to stretch to fill the area provided for the xref:System.Windows.Controls.MediaElement. To preserve the media's original aspect ratio, either the xref:System.Windows.FrameworkElement.Width%2A or xref:System.Windows.FrameworkElement.Height%2A property should be set but not both. Setting both the xref:System.Windows.FrameworkElement.Width%2A and xref:System.Windows.FrameworkElement.Height%2A properties will cause the media to present in a fixed element size that may not be desirable.
To avoid having a fixed size element which, [!INCLUDETLA#tla_winclient] can preroll the media. This is done by setting the xref:System.Windows.Controls.MediaElement.LoadedBehavior%2A to either xref:System.Windows.Controls.MediaState.Play or xref:System.Windows.Controls.MediaState.Pause. In a xref:System.Windows.Controls.MediaState.Pause state, the media will preroll and will present the first frame. In a xref:System.Windows.Controls.MediaState.Play state, the media will preroll and begin to play.
MediaPlayer Class
Where as the xref:System.Windows.Controls.MediaElement class is a framework element, the xref:System.Windows.Media.MediaPlayer class is designed to be used in xref:System.Windows.Media.Drawing objects. Drawing objects are used when you can sacrifice framework level features to gain performance benefits or when you need xref:System.Windows.Freezable features. xref:System.Windows.Media.MediaPlayer enables you to take advantage of these features while providing media content in your applications. Like xref:System.Windows.Controls.MediaElement, xref:System.Windows.Media.MediaPlayer can be used in independent or clock mode but does not have the xref:System.Windows.Controls.MediaElement object's unloaded and loaded states. This reduces the playback control complexity of the xref:System.Windows.Media.MediaPlayer.
Controlling MediaPlayer
Because xref:System.Windows.Media.MediaPlayer is stateless, there are only two ways to control media playback.
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Interactive control methods. In place when in independent mode (
nullxref:System.Windows.Media.MediaPlayer.Clock%2A property). -
xref:System.Windows.Media.MediaClock. In place when media has a xref:System.Windows.Media.MediaPlayer.Clock%2A.
Displaying a MediaPlayer
Technically, a xref:System.Windows.Media.MediaPlayer cannot be displayed since it has no physical representation. However, it can be used to present media in a xref:System.Windows.Media.Drawing using the xref:System.Windows.Media.VideoDrawing class. The following example demonstrates the use of a xref:System.Windows.Media.VideoDrawing to display media.
[!code-csharpDrawingMiscSnippets_snip#VideoDrawingExampleInline]
See the Drawing Objects Overview for more information about xref:System.Windows.Media.Drawing objects.