How to check whether HDR video is really playing in HDR on your Mac

HDR can be hard to diagnose by eye. A bright picture is not proof that HDR is active, and a restrained picture is not proof that it is broken. The source may be SDR, the display may have limited headroom, or the player may be interpreting incomplete metadata.

1. Confirm the source is HDR

Inspect the file rather than relying on its name or a streaming-service badge. Look for an HDR transfer function such as PQ (also called SMPTE ST 2084) or HLG, and check the colour primaries and bit depth. BT.2020 primaries are common in HDR, but by themselves do not prove that a video is HDR. Metadata can also be missing or wrong, especially in files that have been remuxed or converted.

2. Check the display you are using

Verify that your built-in screen or external monitor supports HDR and that macOS is using the intended display mode. A window moved to another monitor may have a different amount of highlight headroom. Compare results on one screen at a time and leave its picture settings unchanged.

3. Read the player’s detected colour information

A useful playback inspector should show the detected transfer, primaries, matrix, and range. It should also make clear when a value was inferred rather than read from the file. If the player reports SDR for a known HDR source, or has to infer several key tags, investigate the file and player support before adjusting your display.

Stoic’s playback features include a live inspector for source colour and playback details. Supported transfers include PQ and HLG, alongside SDR formats.

4. Check playback stability separately

HDR colour and smooth motion are separate questions. Check the source frame rate, the display refresh rate, and whether frames are being dropped. A colour mismatch will not be fixed by changing refresh rate; dropped frames will not be fixed by changing the transfer function.

Stoic’s benchmark page shows one documented test setup and its limits. Results vary with the file, Mac, display, and player version, so treat any single benchmark as evidence for that setup rather than a universal ranking.

5. Compare a known frame before changing anything

Pause a scene you know well and compare the exact same frame in each player. Keep display settings and window size fixed. Look for highlight detail and shadow gradation, not simply which image appears brighter. If a change makes the image brighter but erases detail, it may be a different tone-mapping choice rather than more accurate HDR.

When HDR still looks wrong

• Re-check the file’s tags and profile; a filename is not a format report.
• Try a second known HDR sample to separate file issues from player issues.
• Make sure the display has not changed modes between comparisons.
• Record the Mac, macOS version, player version, display, and file details.

The most useful diagnosis is specific: “this file reports PQ, BT.2020, 10-bit on this display, but the player reports SDR.” That gives you something concrete to investigate instead of another round of random brightness adjustments.