Hi, does the official Videoplayback sample runs fine on the Nexus ?

Yes before adding this part every thing was fine nexus also.if i was playing video in main ui thread it was playing the video.but when i use async task toavoid heavy operation on main thread and shown a progress dialog, this issue comes.App is stoped unfortunatelly.

Sounds like a threading issue... perhaps the Nexus is the only one which shows the problem, but maybe you have a bug and it only shows up on the Nexus.

can you explain a bit better (or share code snippet) what you do with the AsyncTask ?

I am staring a new activity in which i am starting the relevent video in media player, i used asyn task to prepare media player and till then i am showing a progress bar and  dismiss when video is prepared.except it i am not doing anything in async task.

 protected String doInBackground(String... params)
        {
        // code to be executed in background thread

            holder = mPreview.getHolder();
            holder.addCallback(MediaPlayerDemo_Video.this);
            holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
            extras = getIntent().getExtras();

        return "Executed";
        }

I have dismiss progress dialog in onprepared method.I dont have nexus for now so i am unable to put logcat.

Are you properly using onProgressUpdate() and onPostExecute() as explained here:

http://developer.android.com/reference/android/os/AsyncTask.html

?

I have left codeless these methods like this.

        @Override
        protected void onPreExecute() {
                    }

        @Override
        protected void onProgressUpdate(Void... values) {
              }

sholud i do something there.? till then i am going througly your url for async task.

Usually you don't need to implement the onPreExecute();  however the onProgressUpdate() is meant to do things that are supposed to happen in the UI thread (for instance updating a progress bar is something that should be done in that method to ensure thread-safety)

Okay that's fine. But till now i didn't solution why the app is crashing in only google nexus in this activity. is it not allowing me to play video from async task or something else is wrong in this activity.?

Just wondering if you really need to do that in an AsyncTask; the MediaPlayer is already capable of working "in background", see how it is used in our VideoPlayback sample.

Other than that, I don(t have other hints in this case, but perhaps you might have better luck if  search about this topic (MediaPlayer with AsyncTask) in Android-specific forums, as this is probably not a Vuforia-specific issue.