Introducing HDR Video on Reels

**Title: Bringing True HDR Video Support to Facebook and Instagram: Overcoming Technical Challenges**

**Differing Device Support for HDR: A Challenge**

The Transition to HDR Video: Unlocking a New Generation of Visuals

The rollout of HDR cameras and displays has presented a challenge in implementing end-to-end HDR video creation and delivery due to the varying capabilities of different devices. Enabling HDR video creation and upload is more than just supporting specific devices; it requires ensuring compatibility across a diverse range of devices.

Ensuring Compatibility Across Devices

HDR video standards have specific hardware requirements for creation and consumption, and not all devices support these standards. This means that some users may not be able to view HDR content, or they may experience a degraded version with incorrect colors, leading to a less satisfying viewing experience.

The Challenge of Different HDR Formats and Hardware Capabilities

Different HDR formats, such as HLG and PQ, can contain HDR10+ or Dolby Vision dynamic metadata. Additionally, different device manufacturers may implement their own standards, resulting in variations in luminosity range and color gamut support. Even the sensors used in different devices can affect the colors captured. All of these distinctions make it crucial to account for various characteristics to ensure consistent and accurate video playback across all devices.

The Need for Accurate Tone Mapping

As not all devices support HDR displays, providing backward compatibility with SDR representation is essential. Tone mapping, the process of scaling down the dynamic range and color space of an image or video, must preserve the original appearance while adapting it for SDR. Improper tone mapping can result in color shifts and videos that are too bright or too dark.

Automated Tone Mapping Solutions

In a professional studio, tone mapping is manually adjusted to achieve pleasing results. However, with billions of videos to process, automated solutions are necessary. Sophisticated algorithms can be used to preserve quality and minimize artifacts introduced during tone mapping. While objective visual quality metrics for tone mapping are still being researched, implementing popular tone mapping operators that closely resemble the original HDR video can yield satisfactory results.

Client-side Tone Mapping for HDR Content Upload

Initially, the media pipeline was not prepared to handle 10-bit colors when creators began uploading HDR video content. This resulted in overexposed colors and a dissatisfying experience. For iOS devices, we used Apple’s native tone mapping APIs to convert HDR videos to SDR color space on the device itself before uploading to the servers. This ensured consistent visual quality across all devices.

Addressing Android-Tailored Tone Mapping Challenges

Android devices presented a different set of challenges due to a lack of standardization for HDR in the early stages. We couldn’t rely on OS-level tone mapping alone to maintain a consistent appearance for HDR content. We developed custom tone mapping shaders to accurately convert both PQ and HLG HDR videos to accurate SDR representations. By determining the transfer function used and applying appropriate transformation matrices, we were able to overcome the issue of washed-out colors.

Tone Mapping on the Server: Enabling a Full HDR Experience

While client-side tone mapping resolved issues with visual quality degradation, the ultimate goal was to deliver a full HDR experience on newer devices with HDR displays. This required building robust end-to-end HDR support while ensuring a satisfying user experience on older devices without HDR support.

Conclusion:

Meta has successfully enabled the upload and playback of HDR videos on Facebook and Instagram’s Reels. Overcoming technical challenges related to differing device support and accurate tone mapping has allowed for a seamless transition to HDR video. This advancement in video technology brings users closer to true-to-life visuals, enhancing the viewer experience and setting the stage for future video advancements.