Multimedia

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Multimedia

• Rujchai Ung-arunyawee
• Department of Computer Engineering
• Khon Kaen University

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Multimedia

• Image
• Sound
• Videos

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The Image
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The SoundPlayer

• Appeared in .NET 2.0
• The easiest, most lightweight way to add audio to
  an application
• Only play audio WAV files
• Doesnt support playing more than one sound at
  once
• Doesnt provide the ability to control

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Case 1 The audio is present in the same
directory as the compiled application
Case 2 if you add the ding.wav audio file with
the resource name Ding
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The SoundPlayerAction

• New feature that WPF introduces to make it more
  convenient to use the SoundPlayer class
• Allows you to use it in response to any event
• Uses a single property, Source
• Cannot play the audio in an embedded resource

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System Sounds

• Based on the MessageBeep Win32 API
• Provides access only to the following generic
  system sounds
• Asterisk
• Beep
• Exclamation
• Hand
• Question
• For example, to sound a beep in your code

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The MediaPlayer

• Not only play WAV audio, but also play MP3 audio
  or MPEG video

• Note
• The MediaPlayer is created outside the event
  handler
• You supply the location of your file as a URI.
• Theres no exception handling code

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Using these members, you could build a basic but
full-featured media player. However, WPF
programmers usually use another quite similar
element, which is defined in the next section
the MediaElement class.
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The MediaElement

• Wraps all the functionality of the MediaPlayer
  class.
• Used as audio or video player
• Placed a tag directly in your user interface
• Declaratively supported.

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Simple Audio Player

• Adding this markup to your user interface, the
  test.mp3 audio will be played as soon as its
  loaded (which is more or less as soon as the
  window is loaded).

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Playing Audio Programmatically

• To play audio programmatically, you must begin by
  changing the LoadedBehavior
• Interact with the media element in code
• Generally, interaction consists of the
  straightforward Play(), Pause(), and Stop()
  methods

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Handling Errors
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Control media declaratively

• By using the Trigger, Storyboard and
  MediaTimeline
• The following markup demonstrates a simple
  example. It uses the BeginStoryboard action to
  begin playing a sound when the mouse clicks a
  button

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Controlling playback
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Playing Multiple Sounds
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Synchronizing an Animation with Audio

• Simpler way is to segment the audio into
  separate files
• The other way is to use key frame animation by
  wrapping this key frame animation and your
  MediaTimeline into a single storyboard
• When using key frame animation, its important to
  set the Storyboard.SlipBehavior property to Slip
• See text for example.

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Playing Video

• MediaElement class supports all the video formats
  that are supported by Windows Media Player
• Most important, the Stretch and StretchDirection
  properties determine how the video window is
  scaled to fit its container

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Video Effects

• You can use a MediaElement as the content inside
  a content control, such as a button.
• You can also combine video with transformations
  through the LayoutTransform or RenderTransform
  property. This allows you to move your video
  window, stretch it, skew it, or rotate it.
• You can set the Clipping property of the
  MediaElement to cut down the video window to a
  specific shape or path
• You can set the Opacity property to allow other
  content to show through behind your video window

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Video Effects (Cont.)

• You can use an animation to change a property of
  the MediaElement (or one of its transforms)
  dynamically.
• You can copy the current content of the video
  window to another place in your user interface
  using a VisualBrush, which allows you to create
  specific effects like reflection.
• You can place a video window on a 3-D surface and
  use an animation to move it as the video is being
  played

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See text for the code
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Speech Synthesis

• A feature that generates spoken audio based on
  text you supply
• Speech synthesis isnt built into WPFinstead,
  its a Windows accessibility feature.
• Narrator use speech synthesis to help blind users
  to navigate basic dialog boxes
• More generally, speech synthesis can be used to
  create audio tutorials and spoken instructions
• All you need to do is create an instance of the
  SpeechSynthesizer class from the
  System.Speech.Synthesis namespace and call its
  Speak() method with a string of text

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Use PromptBuilder for more controlable
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Speech Recognition

• A feature that translates user-spoken audio into
  text
• As with speech synthesis, speech recognition is a
  feature of the Windows operating system.
• Allows users with disabilities to interact with
  common controls by voice
• Allows hands-free computer use, which is useful
  in certain environments.

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To use speech recognition

• The most straightforward way to use speech
  recognition is
• Create an instance of the SpeechRecognizer class
  from the System.Speech.Recognition namespace
• Then attach an event handler to the
  SpeechRecognized event, which is fired whenever
  spoken words are successfully converted to text
• Retrieve the text in the event handler from the
  SpeechRecognizedEvent-Args.Result property

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