Background and Problem Statement

HDR brightness in playback remains to be the top challenge to address. What are the common HDR brightness problems reported by our UGC partners?

The "flash bang" effect

This problem happens when scrolling full-screen short-form clips in mixed video formats (SDR vs HDR). When switching from HDR-to-SDR or SDR-to-HDR, there is a short brightness ramp period between the videos. Particularly when scrolling between HDR and SDR video in a dark environment and with the device display brightness setting at any level above 0%, the sudden brightness change between HDR and SDR often lead to user complaints known as the "flash bang" effect. 

Mixing SDR and HDR

There are few problems could happen when mixing SDR and HDR.

• Dimmed SDR overlays: This happens when adding SDR overlays as another UI layer on top of HDR video. In this case, Android will boost display brightness due to the existence of HDR video, making the SDR overlays in another UI layer dimmed and often affecting its readability if not managed correctly.
• Incorrect color: This happens when adding SDR UI elements like graphics or text in the same UI layer as HDR video frames or adding SDR frames in between HDR frames. If the SDR UI elements or frames are not correctly converted to HDR, the color of SDR would be incorrect and sometime appear as "washed out".

SDR tone-mapping

This problem happens when displaying HDR on a SDR-only device or mixed video formats (SDR vs HDR) in grid views. When displaying SDR and HDR videos in a grid view, the thumbnail of HDR video could be much brighter than SDR in a browsing grid. And HDR video would also be too bright when playback in a floating front window while user browsing SDR videos in the background.

HDR brightness management solutions in Android

This article provides an overview about potential solutions for Android app developers to address the HDR brightness problems. Note that we only present methods for managing brightness - it’s up to you to adjust the desired HDR content brightness.

Android 15 and newer

With the release of Android 15, Google introduced the capability of manage HDR headroom at the application level by using setDesiredHdrHeadroom method. This method allows app developer control HDR video brightness during playback by setting a desired ratio of targetHDRPeakBrightnessInNits / targetSDRWhitePointInNits. If this method is not used, the HDR brightness will be determined based on default values defined by the OEM.

Below is a sample code demonstrating how to use setDesiredHdrHeadroom.

surfaceView = itemView.findViewById(R.id.surfaceView);
 
public void surfaceCreated(SurfaceHolder holder) {
    ...
    surfaceView.setDesiredHdrHeadroom(desiredHdrRatio);
    ...
}

Android 14

In Android 14, there are two approaches for managing HDR brightness depending on whether the device is based on a Display Processing Unit (DPU) or a Graphics Processing Unit (GPU). The simplest way to determine whether a device is DPU-based or GPU-based is by checking the name of the decoder implemented on the device.

More details about DPU and GPU solutions, as well as how to identify which solution a device is based on, can be found in the Dolby Vision Editor project documentation.

DPU-based Dolby Vision devices

On DPU based devices, to manage the HDR boost ratio at the application level you can use the setExtendedRangeBrightness method in SurfaceControl.Transaction.

Below is an example of how to properly use setExtendedRangeBrightness to set the desired brightness level for HDR content.

Step 1: Set up the SurfaceControl

Create a SurfaceControl instance and connect it to your SurfaceView. This assumes your application is using SurfaceView for video rendering.

SurfaceControl newParentSurfaceControl = surfaceView.getSurfaceControl();
SurfaceControl surfaceControl = new SurfaceControl.Builder()
					.setName(SURFACE_CONTROL_NAME)
					.setParent(newParentSurfaceControl)
					.build();

Step 2: Configure HDR ratio

Create a transaction to manage surface properties, then set the desired HDR ratio for your video content.

Note: For rendering HLG or PQ contnet, the currentHdrRatio must be set to 1.0f. For reference, see the Android API documentation. See setExtendedRangeBrightness Android API documentation.

int dataSpace = DataSpace.pack(DataSpace.STANDART_BT2020,DataSpace.TRANSFER_HLG, DataSpace.RANGE_LIMITED);

SurfaceControl.Transaction transaction = new SurfaceControl.Transaction();
transaction.setDataSpace(surfaceControl, dataspace)
   .setExtendedRangeBrightness(surfaceControl, 1.0f, desiredHdrRatio)
   .setVisibility(surfaceControl, true)
   .setBufferSize(surfaceControl, video_width, video_height)
   .apply();

Step 3: Submit video buffer

Use the transaction instance to submit the video buffer to the surface.

// HardwareBuffer output is the video buffer
Consumer<SyncFence> releaseCallback =
        syncFence -> {
            // Handle the release of the SyncFence
            if (syncFence != null) {
                syncFence.awaitForever();
                syncFence.close();
 
                output.close();
            }
        };

transaction.setBuffer(surfaceControl, output, null, releaseCallback).apply();

GPU-based Dolby Vision devices

There is no good solution today for GPU based devices. On majority of devices, the setExtendedRangeBrightness method does not work. There is also no alternative method that would provide proper brightness management and deliver consistent results across these devices.

Android 13 and older

Based on our limited test, HDR brightness issue does not seem relevant to this devices running Android 13 and older.