Multimedia Engine in QuickTime for Java

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Multimedia Engine in QuickTime for Java
Academic Developers Conference 2001

• Dhammika Ruberu Phillip McKerrow
• University of Wollongong

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Introduction

• Why ?
• Design of the application
• Examine the MMBuilder
• Implementation details
• Why did we use certain methods?
• Interesting findings and pitfalls

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Why develop another multimedia engine?

• Easy to use for non programmers
• Identify the minimum feature set for a useful
  multimedia engine
• Be able to extend to meet the changing needs

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Design
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Linking of Screens
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Structure of the editor (MMBuilder)

• Consists of 4 separate windows
• Media catalogue
• Editor window
• Object inspector
• Screen manager

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MMBuilder

• Media Catalogue
• Can import any media
• type supported by
• QuickTime

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Editor window

• Operate in two modes
• Editor mode
• Run mode
• Layout media elements
• Set QuickTime attributes

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Editor window - Cont.

• Setting QuickTime movie attributes

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Object inspector

• Change object properties
• Create a hot object

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Screen manager
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Implementation details
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Background to QuickTime for Java API

• Not very Java like
• QTJ object is a handle to an underlying QuickTime
  object
• Refer to original QuickTime documentation

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Main QTJ building blocks

• QTCanvas
• DirctGroup
• Compositor

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Structure of mmScreen
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Highlighting the selected object

• Make a compositor of the same size as the
  selected object
• Create an image of the selected object
• Create a QuickDraw graphic of the one pixel
  outline
• Add the outline and the image to the compositor
• Replace the selected object with the composite
  image
• Add DragAction to drag the created composite image

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Matrix manipulation

• Object inspector is implemented using matrix
  manipulation
• Matrix operations are additive, but we wanted
  them to be absolute
• m.setIdentity ()
• m.translate ((float) x, (float) y)
• m.scale (scale, scale, x, y)
• m.rotate (rotation, (float) x, (float) y)

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Object serialisation

• Project is saved using Java object serialisation
• class mmScreen extends Component implements
  Serializable
• static final long serialVersionUID
  -123456789012345L
• private transient DirectGroup dg
• private transient Compositor cm
• private LayerManager lm

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Object serialisation - Cont.

• When writing data
• private void writeObject (ObjectOutputStream
  out)
• throws IOException
• removeHilight ()
• out.defaultWriteObject ()

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Object serialisation - Cont.

• When reading data
• private void readObject (ObjectInputStream in)
• throws IOException, ClassNotFoundException
• in.defaultReadObject ()
• initScreen ()
• lm.setDirectGroup (dg)
• lm.setCompositor (cm)
• lm.restoreScreen ()

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Making a movies background transparent

• Done using QuickTime ink effects
• //Make it transparent
• GraphicsMode gm new GraphicsMode
  (QDConstants.transparent, QDColor.black)
• cm.getMemberSprite (qtObj).setGraphicsMode (gm)
• //Revert to normal by applying an empty
  GraphicsMode
• GraphicsMode gm new GraphicsMode ()
• cm.getMemberSprite (qtObj).setGraphicsMode (gm)

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Porting to OS X

• Done using the Project Builder
• Minimal changes were needed
• File name mismatch with class name
• Changes to the file IO

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QA