Hey there! Your request to build a partial-screen menu app that overlays on top of Android TV's background video playback (from Live Channels) is totally achievable—you don't need to reinvent any video playback logic, just hook into Android TV's existing media stack and configure your app properly.

Here's a breakdown of the key APIs and steps to make this work:

1. Configure Your Activity's Transparent, Partial-Screen Theme #

The first critical step is to set up your app's main Activity so it doesn't block the background video. Add these settings to your Activity in AndroidManifest.xml:

<activity
    android:name=".YourMenuActivity"
    android:theme="@style/TransparentLeanbackTheme"
    android:launchMode="singleTop"
    android:excludeFromRecents="true">
</activity>

Then define the transparent theme in styles.xml—optimized for Android TV:

<style name="TransparentLeanbackTheme" parent="Theme.Leanback">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:backgroundDimEnabled">false</item>
</style>

This ensures your Activity's window is transparent and won't obscure the background video.

2. Avoid Interrupting Background Media Playback #

To keep the Live Channels video playing in the background, your app must not steal media focus:

• If your menu has no audio: Skip requesting audio focus entirely. This lets the background media continue playing uninterrupted.
• If you need menu sounds: Request transient ducking focus so background audio lowers temporarily instead of pausing:

AudioManager audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
int result = audioManager.requestAudioFocus(
    null,
    AudioManager.STREAM_MUSIC,
    AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK
);

3. Design Your Partial-Screen Menu Layout #

Build your menu UI to occupy only a portion of the screen (e.g., left sidebar) using standard Android layout tools. For example, with ConstraintLayout:

<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/transparent">

    <!-- Menu container - takes only 300dp width on the left -->
    <LinearLayout
        android:id="@+id/menu_container"
        android:layout_width="300dp"
        android:layout_height="match_parent"
        android:background="@color/your_menu_background"
        app:layout_constraintStart_toStartOf="parent"
        android:orientation="vertical">

        <!-- Add your menu items here (buttons, text, etc.) -->

    </LinearLayout>

    <!-- The rest of the screen stays transparent, showing the background video -->
</androidx.constraintlayout.widget.ConstraintLayout>

4. Keep the Screen Active #

Since the background video requires the screen to stay on, add this flag in your Activity's onCreate method:

getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

Key Reminders #

• You do not need to develop any video playback functionality—this relies entirely on Android TV's native ability to keep Live Channels playing in the background when another app launches.
• Never use fullscreen flags (like FLAG_FULLSCREEN) as this will hide the background video.
• Test thoroughly: Launch Live Channels, press Home, then open your app to confirm the video continues playing behind your menu.

Content of the question comes from stack exchange, question author Fez Vrasta