Sample for refresh rate switching during playback

MainActivity.kt

/* Copyright 2021 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */

// Determine whether the transition will be seamless.
// Non-seamless transitions may cause a 1-2 second black screen.
val refreshRates = display?.mode?.alternativeRefreshRates
val willBeSeamless = Arrays.asList<FloatArray>(refreshRates).contains(newRefreshRate)
if (willBeSeamless) {
    // Set the frame rate, but only if the transition will be seamless.
    surface.setFrameRate(newRefreshRate,
                         FRAME_RATE_COMPATIBILITY_FIXED_SOURCE,
                         CHANGE_FRAME_RATE_ONLY_IF_SEAMLESS)
} else {
    val prefersNonSeamless = (getSystemService(Context.DISPLAY_SERVICE) as DisplayManager)
            .getMatchContentFrameRateUserPreference() == MATCH_CONTENT_FRAMERATE_ALWAYS)
    if (prefersNonSeamless) {
        // Show UX to inform the user that a switch is about to occur
        showUxForNonSeamlessSwitchWithDelay();
        // Set the frame rate if the user has requested it to match content
        surface.setFrameRate(newRefreshRate,
                             FRAME_RATE_COMPATIBILITY_FIXED_SOURCE,
                             CHANGE_FRAME_RATE_ALWAYS)
    }
}