# Daydream Media App Template ![](https://developers.google.com/static/vr/images/PlaybackControls.png) The Media App Template demonstrates best practices for building media-viewing apps on Daydream. The template can be used out-of-the-box to view media content that is stored locally on a user's device. The template can also be customized to fit your desired style or adapted to view streamed content from a server. [Download on GitHub](https://github.com/googlevr/media-app-template) This template includes the following features, all of which are fully customizable or removable depending on your specific use case: - **Permissions Flow**: This feature lets users leave VR temporarily to grant required permissions. - **File Selector**: This feature uses paginated scrolling to allow users to navigate their file system to select media files. - **Media Player**: The player or set of players used to display selected media. - **Playback Controls**: The set of controls used to manipulate the media player. - **Storyboard**: The preview window that shows a given frame when the user hovers over the video scrubber. - **Screen Manipulation**: This feature lets users move the media player to allow for various viewing positions. - **Screen Lighting**: This feature lights the screen, increasing the sense of realism. - **Controller Idling**: This feature hides the controller when it's idling. - **Media Format Detection**: The feature that automatically detects the stereoscopic and projection format of a selected media file and lets you match it to a proper media player. > [!NOTE] > **Note:** The Media App Template includes a modified version of the GVRVideoPlayer. As a result, the Media App Template has a modified version of the file GvrVideoPlayerTexture.cs located in MediaAppTemplate/Scripts/GvrVideo. If you choose to use a version of the GVR SDK for Unity other than the one included with the Media App Template, you must delete the version of GvrVideoPlayerTexture.cs that comes with the SDK. ## Permissions Flow To view sideloaded content the user must grant the app READ_EXTERNAL_STORAGE permission, which requires the user to exit VR. The media template app handles this by using `PermissionsFlowController`, a script attached to the `PermissionsFlow` prefab. The flow works as follows: - Upon launching, PermissionsFlowController checks if READ_EXTERNAL_STORAGE permissions need to be granted by using GvrPermissionsRequestor, included with the Google VR SDK for Unity. - If permissions are required, a message is displayed in VR informing the user that they need to grant permissions to continue. The message provides a button that the user needs to press to proceed. Both these UI elements are child objects of the `PermissionsFlow` prefab. - Upon pressing the button, the user is instructed to remove their phone from the headset. After removing the phone, the user is prompted to grant the needed permission. After permissions are granted, the user is returned to VR. - When PermissionsFlowController detects that permissions have been granted, it destroys itself and instatiates a prefab specifed through serialization to kickoff the next flow. In this case, that's File Selector. ## File Selector ![](https://developers.google.com/static/vr/images/FileSelector.png) The File Selector is a UI that uses paginated scrolling to navigate the file system to select files (In this case, videos and photos). It can also be modified to navigate videos and photos coming from sources other than the file system. The UI includes a breadcrumb trail used to show where the user is in the folder hierarchy and allow navigation back up the file hierarchy. The UI is managed by the class `FileSelectorPageProvider`. This class is also responsible for setting the breadcrumb trail. A `Breadcrumb` is a clickable UI element for a particular piece of `BreadcrumbData`. When clicked, `FileSelectorPageProvider` registers the event and updates the UI and the `BreadcrumbTrail` accordingly. ## Media Player The Media App Template supports having a variety of media players that play a variety of types of media. The out-of-the-box media player is a basic implementation that will display videos and photos. The player also detects whether a video or photo is spherical or stereoscopic and display it in the proper format. it will The basic media player is managed by the class `BaseMediaPlayer`. The concrete implementation of the media players is hidden behind abstract classes. You can easily replace the implementation with custom media players by creating custom subclasses of `BaseMediaPlayer`. When a file is selected by the File Selector, the `MediaSelector` class will create the correct type of media player based on the file that was selected. ## Playback Controls Playback controls are the UI elements used to control the media player, such as the skip forward, skip backward, pause, and restart buttons. Some of them work with all types of media while some of them only work with videos or photos. Playback controls that are not compatible with the current media player are automatically hidden and the layout is adjusted accordingly. `PlaybackControlsManager` is responsible for toggling the playback controls on/off when a click occurs and when the controls have been idle for several seconds. `PlaybackControls` is responsible for setting up all of the `IPlaybackControl` implementations that are on children of the `PlaybackControls`. ## Storyboard When the user hovers over the video scrubber, a small preview window pops up above the pointer, displaying a frame close to that point in the video. We call that preview window the Storyboard and the individual frames Storyboard frames. The class `PlaybackScrubber` instantiates a prefab of type `BaseVideoPlayerStoryBoard` when the pointer begins hovering over the `PlaybackScrubber`. The Media App Template comes with one implementation of `BaseVideoPlayerStoryboard` called `LocalVideoPlayerStoryboard`. This implementation uses an android plugin to grab keyframes of local video files and stores them in an LRU cache. It divides the video into 50 segments and displays the closest keyframe for each segment. > [!NOTE] > **Note:** If providing videos from a server, we recommended you preprocess the video into a series of storyboard frames on the server and create a custom implementation of `BaseVideoPlayerStoryboard` to download those frames. ## Screen Manipulation Screen manipulation functionality allows the user to reposition and resize the screen. This makes the media app usable in multiple positions, such as lying in bed When switching between videos and photos, the screen's position and scale are maintained so that you don't need to re-adjust it every time you enter a new video. The file selector can be similarly repositioned. The class `MediaScreenController` is used to reposition the screen when drag events occur and to resize the screen when scroll events occur. `MediaScreenController` must be placed on the same game object as the screen itself. ## Screen Light Real screens emit light which in turn affects the ambient light around them. The media app template mimics this effect by using the class `AverageColorCalculator` to determine the average color emitted by the media. The screen light is then used in conjuction with a Unity light to render the light with the correct intensity and color from th e screen. These scripts are used in the `FlatVideoScreen` and `FlatPhotoScreen` prefabs. ## Controller Idling To prevent the controller UI from distracting the user while they are watching a video, the controller goes into an idle state when it hasn't been moved for a few seconds as determined by the `ControllerIdleCondition` class. The class `HideOnConditions` is used to hide the laser and the reticle after the appropriate idle time. This class can react to a number of conditions using the `ConditionsManager` singleton. Each condition is an implementation of `BaseCondition`, which registers itself with `ConditionsManager` when enabled. Example implementation of `BaseCondition` include `PointerHoveringCondition`, `ControllerIdleCondition`, and `PlaybackControlsOpenCondition`. ## Media Format Detection There is a current lack of standardization for detecting the stereo or projection format of videos and photos. Media App Template can detect format in three ways: - By checking what format was used the last time the file was played. - By analyzing the video metadata. - By analyzing the image itself. Additionally there is a menu accessible when the playback controls are open that allows the user to manually change the format in case the detected format is incorrect. Each manner of detection is handled by a projection detector that inherits from the class `BaseStereoProjectionDetector`. The drojection detectors are stored in a prioritized list by the media player, and the media file will play in the format detected by the highest priority detector that was able to successfully find a format. If no format is detected, it will default to flat and mono. This is the list of project detectors in order of priority: - `SavedStereoProjectionDetector` - Most recently used format the last time the file was used. - Stores the format in-between sessions in the persistentDataPath. - `VideoMetadataProjectionDetector` - Attempts to determine the format based on the [metadata format specified here](https://github.com/google/spatial-media/blob/master/docs/spherical-video-v2-rfc.md). - Depends on the [Google VR Video Plugin](https://developers.google.com/vr/video/video-overview). - `ImageBasedProjectionDetector` - Attempts to detect the format by analyzing an image. For videos, takes a frame one quarter of the way through the video.