Does WebM Support HDR Video Profiles?

High Dynamic Range (HDR) video has become a standard for delivering rich colors and deep contrast, leaving many developers and creators wondering if the WebM container format supports it. Yes, the WebM specification fully supports HDR video profiles, primarily when utilizing the VP9 and AV1 video codecs alongside Matroska-based metadata. This article explores how WebM handles HDR data, the specific codecs required, and the current state of browser and platform compatibility for streaming WebM HDR content.

Codec Requirements for WebM HDR

The WebM container itself is a subset of the Matroska (MKV) format, which means it inherits the ability to carry block additions and metadata required for HDR. However, the container is only a wrapper; the actual support for HDR depends heavily on the video codec used inside it.

VP9 (Profile 2 and Profile 3): Standard VP9 (Profile 0) only supports 8-bit color. To achieve HDR, the WebM file must use VP9 Profile 2 (10-bit color) or Profile 3 (12-bit color). Profile 2 is the most widely adopted standard for VP9 HDR, utilizing \(YUV420\) color sampling.
AV1: As the successor to VP9, the AV1 codec natively supports 10-bit and 12-bit color depths across its main profiles, making it highly efficient for encoding high-quality HDR content within a WebM container.

Supported HDR Formats and Metadata

To display HDR correctly, the video file must pass specific color signaling metadata to the display hardware. WebM supports the essential elements required for major HDR formats:

HLG (Hybrid Log-Gamma): Well-supported for broadcast-style HDR streaming, relying on specific transfer functions signaled in the WebM track headers.
HDR10: WebM accommodates the static metadata required for HDR10, including Mastering Display Color Volume (MDCV) and Content Light Level (CLL) data.
Color Spaces: It supports wide color gamuts such as Rec. 2020 (\(BT.2020\)), alongside the SMPTE ST 2084 (PQ) transfer function.

Browser and Platform Compatibility

While the WebM specification technically supports HDR, actual playback depends on the browser, operating system, and hardware capabilities of the user’s device.

Browser / Platform	HDR WebM Support Status	Notes
Google Chrome	Full Support	Natively supports VP9/AV1 HDR on compatible OS and HDR monitors.
Microsoft Edge	Full Support	Inherits Chromium support; requires Windows HDR settings to be enabled.
Mozilla Firefox	Partial/Full Support	Supports VP9 and AV1 HDR, though performance can vary based on OS graphics pipelines.
Apple Safari	Limited	Historically prefers MP4/MOV (HEVC) for HDR, though modern versions have expanded AV1/WebM support on newer Apple Silicon hardware.

For successful deployment, web developers typically use the HTML5 <video> tag with appropriate source types, allowing the browser to fall back to alternative formats like MP4/HEVC if the user’s platform lacks native WebM HDR decoding capabilities.