Windows phone 7 - unable to play audio under lock screen - windows-phone-7

Question

I am developing an app for windows phone 7. There is a media element which plays video from a url. When i lock the phone, the audio and video stops playing. I have tried disabling ApplicationIdleDetetction and i have handled Rootframe Obscured and Unobscured. I just couldn't figure out how to continue playing the audio when the phone is locked.
Any help on this is greatly appreciated !!
thanks
graham

Answer 1

Use the AudioPlayerAgent to keep the music playing even when the phone gets locked!
Check the "Background Audio Player Sample" on the Windows Phone Code Samples.

Answer 2

Video will automatically stop playing when the screen is locked - that is a built-in system feature. Think of it as a fail-safe for applications that will drain the device battery by playing video in the background, which is an unnecessary task anyway - who watches the content? ApplicationIdleDetection won't help with this task at all.
If you have a separate audio stream, you could use AudioPlayerAgent, that can be used to play both local and remote audio streams.
Read this:
Background Audio Overview for Windows Phone
How to: Play Background Audio for Windows Phone
Streaming Audio in Windows Phone

Answer 3

You can do this with a dispatcher timer. Here is an example of how I do it in my app Searchler (This feature not yet in marketplace, update coming very soon!) using the MMP Player Framework available # http://smf.codeplex.com/
namespace Searchler.Views
{
public partial class PlayerView : PhoneApplicationPage
{
bool appUnderLock = false;
DispatcherTimer dispatcherTimer = new DispatcherTimer();
}
public PlayerView()
{
InitializeComponent();
//Hack to enable play under lock screen
UIThread.Invoke(() => VideoPlayer.PlayStateChanged += VideoPlayer_PlayStateChanged);
UIThread.Invoke(() => (Application.Current as App).RootFrame.Obscured += RootFrame_Obscured);
UIThread.Invoke(() => (Application.Current as App).RootFrame.Unobscured += RootFrame_Unobscured);
dispatcherTimer.Tick += dispatcherTimer_Tick;
dispatcherTimer.Interval = new TimeSpan(0, 0, 3);
}
void dispatcherTimer_Tick(object sender, EventArgs e)
{
if( VideoPlayer.PlaybackPosition == VideoPlayer.EndPosition)
((PlayerViewModel)DataContext).Next(); //Custom GetNext Video Method
}
void RootFrame_Unobscured(object sender, EventArgs e)
{
dispatcherTimer.Stop();
appUnderLock = false;
}
void RootFrame_Obscured(object sender, ObscuredEventArgs e)
{
dispatcherTimer.Start();
appUnderLock = true;
}
}