private void ReleasePlayer()
 {
     if (player != null)
     {
         debugViewHelper.Stop();
         debugViewHelper = null;
         shouldAutoPlay  = player.PlayWhenReady;
         UpdateResumePosition();
         player.Release();
         player               = null;
         trackSelector        = null;
         trackSelectionHelper = null;
         eventLogger          = null;
     }
 }
        // Internal methods

        private void initializePlayer()
        {
            Intent intent        = Intent;
            bool   needNewPlayer = player == null;

            if (needNewPlayer)
            {
                var adaptiveTrackSelectionFactory =
                    new AdaptiveTrackSelection.Factory(BANDWIDTH_METER);
                trackSelector           = new DefaultTrackSelector(adaptiveTrackSelectionFactory);
                trackSelectionHelper    = new TrackSelectionHelper(trackSelector, adaptiveTrackSelectionFactory);
                lastSeenTrackGroupArray = null;
                eventLogger             = new EventLogger(trackSelector);

                var drmSchemeUuid = intent.HasExtra(DRM_SCHEME_UUID_EXTRA)
                                        ? UUID.FromString(intent.GetStringExtra(DRM_SCHEME_UUID_EXTRA)) : null;
                IDrmSessionManager drmSessionManager = null;
                if (drmSchemeUuid != null)
                {
                    var drmLicenseUrl             = intent.GetStringExtra(DRM_LICENSE_URL);
                    var keyRequestPropertiesArray = intent.GetStringArrayExtra(DRM_KEY_REQUEST_PROPERTIES);
                    int errorStringId             = Resource.String.error_drm_unknown;
                    if (Util.Util.SdkInt < 18)
                    {
                        errorStringId = Resource.String.error_drm_not_supported;
                    }
                    else
                    {
                        try
                        {
                            drmSessionManager = BuildDrmSessionManagerV18(drmSchemeUuid, drmLicenseUrl,
                                                                          keyRequestPropertiesArray);
                        }
                        catch (UnsupportedDrmException e)
                        {
                            errorStringId = e.Reason == UnsupportedDrmException.ReasonUnsupportedScheme
                                                                ? Resource.String.error_drm_unsupported_scheme : Resource.String.error_drm_unknown;
                        }
                    }
                    if (drmSessionManager == null)
                    {
                        ShowToast(errorStringId);
                        return;
                    }
                }

                var preferExtensionDecoders = intent.GetBooleanExtra(PREFER_EXTENSION_DECODERS, false);
                var extensionRendererMode   =
                    ((DemoApplication)Application).UseExtensionRenderers()
                                                ? (preferExtensionDecoders ? DefaultRenderersFactory.ExtensionRendererModePrefer
                                                : DefaultRenderersFactory.ExtensionRendererModeOn)
                                                : DefaultRenderersFactory.ExtensionRendererModeOff;
                var renderersFactory = new DefaultRenderersFactory(this,
                                                                   drmSessionManager, extensionRendererMode);

                player = ExoPlayerFactory.NewSimpleInstance(renderersFactory, trackSelector);
                player.AddListener(this);
                player.AddListener(eventLogger);
                player.SetAudioDebugListener(eventLogger);
                player.SetVideoDebugListener(eventLogger);
                player.SetMetadataOutput(eventLogger);

                simpleExoPlayerView.Player = player;
                player.PlayWhenReady       = shouldAutoPlay;
                debugViewHelper            = new DebugTextViewHelper(player, debugTextView);
                debugViewHelper.Start();
            }
            var action = intent.Action;

            Uri[]    uris;
            string[] extensions;
            if (ACTION_VIEW.Equals(action))
            {
                uris       = new Uri[] { intent.Data };
                extensions = new string[] { intent.GetStringExtra(EXTENSION_EXTRA) };
            }
            else if (ACTION_VIEW_LIST.Equals(action))
            {
                var uriStrings = intent.GetStringArrayExtra(URI_LIST_EXTRA);
                uris = new Uri[uriStrings.Length];
                for (int i = 0; i < uriStrings.Length; i++)
                {
                    uris[i] = Uri.Parse(uriStrings[i]);
                }
                extensions = intent.GetStringArrayExtra(EXTENSION_LIST_EXTRA);
                if (extensions == null)
                {
                    extensions = new string[uriStrings.Length];
                }
            }
            else
            {
                ShowToast(GetString(Resource.String.unexpected_intent_action, action));
                return;
            }
            if (Util.Util.MaybeRequestReadExternalStoragePermission(this, uris))
            {
                // The player will be reinitialized if the permission is granted.
                return;
            }
            var mediaSources = new IMediaSource[uris.Length];

            for (var i = 0; i < uris.Length; i++)
            {
                mediaSources[i] = BuildMediaSource(uris[i], extensions[i]);
            }
            var mediaSource = mediaSources.Length == 1 ? mediaSources[0]
                                : new ConcatenatingMediaSource(mediaSources);
            var adTagUriString = intent.GetStringExtra(AD_TAG_URI_EXTRA);

            if (adTagUriString != null)
            {
                Uri adTagUri = Uri.Parse(adTagUriString);
                if (!adTagUri.Equals(loadedAdTagUri))
                {
                    ReleaseAdsLoader();
                    loadedAdTagUri = adTagUri;
                }
                try
                {
                    mediaSource = CreateAdsMediaSource(mediaSource, Uri.Parse(adTagUriString));
                }
                catch (System.Exception)
                {
                    ShowToast(Resource.String.ima_not_loaded);
                }
            }
            else
            {
                ReleaseAdsLoader();
            }
            bool haveResumePosition = resumeWindow != C.IndexUnset;

            if (haveResumePosition)
            {
                player.SeekTo(resumeWindow, resumePosition);
            }
            player.Prepare(mediaSource, !haveResumePosition, false);
            inErrorState = false;
            UpdateButtonVisibilities();
        }