This document discusses using Miracast and the Android secondary display API to output content from an Android device to an external display. It provides an overview of Miracast technology, explains how to use the Android secondary display API to control output to multiple displays since API level 17, and provides examples of code for setting up a presentation on an external display. It also suggests some potential use cases for applications to take advantage of these capabilities, such as using an external display during browsing or turning an Android device into a home office PC.

2. A new application paradigm: Using the 2nd
screen API with Miracast
• Who we are: short recap of LG's Android highlights
• What is Miracast and how can I use it?
• Android API Level 17: The 2nd Screen API hands-on
• Usage Scenarios – what can I do with it?

3. LIFE’S GOOD
WHEN YOU MAKE
THE MOST OF IT!

4. NEXUS 4
Nexus 4 is the new smartphone from Google.
Developed by LG.
With cutting edge hardware, your favorite Google Apps,
and the latest version of Android, Nexus 4
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7. Wi-Fi Miracast

8. What is Miracast?
• Wireless Replacement for HDMI
• Based on existing standards
• Using existing device capabilities
• Open for the industry
• Compliance-tested by Wi-Fi Alliance

9. Miracast Concept
SOURCE SINK
Display frames

Audio samples Render
Synchronized
Render
Video encode Audio encode Video decode Audio decode
Packetize Packetize Depacketize Depacketize
Link content encryption (Optional) Link content decrypt (Optional)
AV mux AV Demux
Transport Transport
LLC LLC
Wi-Fi MAC (direct link) Wi-Fi MAC (direct link)
Wi-Fi PHY Wi-Fi PHY

10. Miracast Logical Block diagram
Game content
UI content
Composited Display
Composition LCD
display surface controller
Video content
Display
capture
Encoded video
Encode
bit-stream
MPEG-2 TS
MPEG-2 RTP
PCM audio Audio/Video Wi-Fi
packeting Transport
mux

11. Sounds Great! Can I Use It Now?
Yes! It is commercially available!
Miracast Source Miracast Display
(e.g. Nexus4, LG Optimus G) (e.g. LG BlueRay Player,
HomeCinema, SmartTV,
Monitor)

12. Android 4.2
Secondary Displays

13. What's the secondary display API?
From 4.2 (API Level 17), Android supports output to multiple displays in
a hardware-agnostic way, which means:
You can implement support for multiple displays in your applications
without having to worry about the way those displays are connected!
You can control the output on this displays independently of the phones
screen!

14. Presentation Class
associated with android.view.Display
Before showing a Presentation it's important to choose
the Display on which it will appear. There are two main
ways to choose a Display:
1. Using the MediaRouter – System will decide
2. Using the DisplayManager – Enumeration of Displays

15. Code Example - How to get a display
protected Display getDisplay() {
if(mUseMediaRouter){
//Use the MediaRouter that supports live video
MediaRouter.RouteInfo route =
mMediaRouter.getSelectedRoute(MediaRouter.ROUTE_TYPE_LIVE_VIDEO);
mCurrentDisplay = route.getPresentationDisplay();
}
else {
// Get all available displays using the DisplayManager
Display[] displays =
mDisplayManager.getDisplays(
DisplayManager.DISPLAY_CATEGORY_PRESENTATION);
// Keep an object to the first available external display
mCurrentDisplay = displays[0];
}
return mCurrentDisplay;
}

16. Getting the displays metrics
You can obtain the metrics with getMetrics() of the external Display in
order to use the proper resources for the external display
Keep in mind that screens
connected to the users device
often have a larger screen size
and likely a different screen
density. Because the screen
characteristics may differ, you
should provide resources that are
optimized specifically for such
larger displays.

17. Simple Example: Presentation
public class TextDemoPresentation extends Presentation {
private TextView mText;
public TextDemoPresentation(Context context, Display
display) {
super(context, display);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Inflate the layout.
setContentView(
R.layout.presentation_text); Hello droidcon!
// Find the TextView field
mText = (TextView)
findViewById(R.id.demoText);
}
}

18. Lifecycle
A presentation is canceled when the display to which it is attached is
removed.
An activity should take care of pausing and resuming whatever content
is playing within the presentation whenever the activity itself is paused
or resumed.
If you use OpenGL in the Presentation the OpenGL context will get lost
on pausing. The only way to keep the context during pause/resume is
to call onPause() and onResume() manually on the GLSurfaceView in
the pause and resume callbacks of your activity.
public void onPause() {
mGLSurfaceView.onPause();
}
public void onResume() {
mGLSurfaceView.onResume();
}

19. Developer Options
Android provides an easy on-device method to test your app using the
secondary display API in the developer option. You can select several
resolutions and once activated you get an overlay emulating the
secondary screen(s)

20. Secondary Displays
A new application
paradigm

21. Use cases - Ideas
Add external Display support to your existing
app in order to utilize other (bigger) displays
when available, e.g. a browser could render
content with the external displays resolution

22. Use cases - Ideas
Add a special mode to your existing application
to show the content on the external display
when available and provide special input mode
on the phone, e.g. just browser input fields and
moving controls

23. Use cases - Ideas
Dedicated apps which work ONLY with external
displays, e.g. a Home Office App to utilize your
phone as PC replacement together with mouse
and keyboard

24. Summary
Miracast is
• a method to transmit audio/video from a mobile
device to external display(s)
• OPEN, STANDARDIZED and COMMERCIALLY
AVAILABLE
Secondary Display API is
• introduced with Android API Level 17
• adds methods to control the content on multiple
displays
Exciting new use cases for applications!!!

25. http://developer.lge.com
Thank you.
Don’t miss the
demo at our www.lgworld.com
booth!