Mediaplayer - Pausing video

[Pinox]

Pausing the media player and then moving to another view and returning back to media player view causes the media player freeze. (unable to restart the media player)

Running latest version VS2017 and latest version Template studio

[crutkas]

@Pinox can you provide a repro?

What framework did you pick?
what navigation pattern? (pivot, navview)

[mrlacey]

With the latest preview releases (VS & WTS)
If selecting a Tabs&Pivot project type, The first time you go to the media player tab the video will start automatically. If you switch to another tab it will pause the video. On returning to the media player tab the video will not restart automatically but will require you to press the play button for it to resume.

This works as intended for me.

[Pinox]

plse find attached the repo. Not using preview version, so just reporting the issue that I see.
Can't restart the player after moving to another page. (with / without pause before moving to another page)

MediaPlayerFreeze.zip

[mrlacey]

Repro

Create a new app (with WTS v1.6.17355.2)

• ProjectType: Navigation View
• Framework: MVVM Light
• Add one MediaPlayer page
• Run generated app.
• Switch to MediaPlayer page > video starts automatically
• press back
• Switch to MediaPlayer page again

Expected
Video to start automatically.
Can open and close the media player page as many times as like and play video each time.

Actual
The video doesn't auto-play and the play button is disabled.
Only possible to play the video the first time the page is loaded.

[mrlacey]

I'm able to reproduce inconsistently with the v1.7 pre-release version.

Unable to reproduce with MVVMBasic.

[ralarcon]

@mrlacey, @dgomezc can have a look on this too... just to be sure that the changes introduced for the Pivot does not have a side effect here (I don't think so, but just to double check).

[mrlacey]

The issue is that the ViewModelLocator (VML) only ever creates a single instance of the MediaPlayer view model and this persistence holds a reference that stops multiple MediaPlayer instances from working correctly.

workaround

The simplest solution is to force the VML to always provide a new instance of the ViewModel by requesting it with a unique key each time. Modifying the VML code to match the below will do it.

public MediaPlayerViewModel MediaPlayerViewModel => ServiceLocator.Current.GetInstance<MediaPlayerViewModel>(Guid.NewGuid().ToString());

There are potentially negative sided effects to doing this, depending on what else the code is modified to do.
If we use this as a solution and change the templates to reflect the above this will make the way the VML handles this VM differently to all the others. Do you think that a comment explaining that and why the VM lifetime is different will be sufficient?

This does not impact the use of the media player page in a pivot app as that manages page (and VM) life-times differently.

I've verified the other frameworks and this only impacts MVVMLight.