ATV4K HDR Metadata Max CLL/FALL

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ATV4K HDR Metadata Max CLL/FALL

I use the ATV4K 3rd gen as a streaming box. I noticed that some shows look very washed out (Andor on Disney+ is a good example). In troubleshooting I found that when content doesn't define HDR metadata, the ATV4K defaults to outputting HDR metadata of 4000/1000 Max CLL/FALL (definitions below). The problem with this is that 4000/1000 is a ridiculously high value. This causes the display to think that it is dealing with incredibly bright content, and it therefore lowers its brightness output to compensate.

Has anybody has found a fix or workaround for this issue?

MaxFALL (Maximum Frame Average Light Level) indicates the maximum value of the frame average light level (in cd/m2 or nits) of the entire playback sequence. MaxFALL is calculated by averaging the decoded luminance values of all the pixels within a frame. MaxFALL is usually much lower than MaxCLL.

MaxCLL (Maximum Content Light Level) indicates the maximum light level of any single pixel (in cd/m2 or nits) of the entire playback sequence. MaxCLL is usually measured off the final delivered content after mastering. If one uses the full light level of the HDR mastering display and adds a hard clip at its maximum value, MaxCLL would be equal to the peak luminance of the mastering monitor.

Posted on Dec 29, 2022 9:03 AM

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Answer 1

Top-ranking reply

justinjas

Level 1

9 points

Jan 15, 2023 8:52 AM in response to AppleFan7512

For what it’s worth this has been an issue ever since the AppleTV first started supporting HDR. For some reason some TVs handle it better than others. For example my LG OLEDs display this HDR content bright enough. But the recent mini LED LG I just got (qned85) is struggling with showing an extremely dim image from HDR content on the Apple TV. The only work around I have for it is to set the Apple TV to be forced into Dolby Vision which renders correctly. I also have a projector that used to struggle with this metadata but they later added a feature to do tone mapping on the projector and ignore the metadata all together which fixed it. I really wish like you said that Apple would fix this by nulling out these values or going with more reasonable baselines or heaven forbid give us an option to set defaults.

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Answer 2

TammyW_03

Community Specialist

Dec 30, 2022 11:53 AM in response to AppleFan7512

Hey AppleFan7512,

In your troubleshooting did you recalibrate the display to see if that helps with the issue you're having? Those steps and other tips can be found here: Adjust video and audio settings on Apple TV - Apple Support

Adjust video settings

You can adjust video settings, such as format, frame rate matching, or test your HDMI connection for any problems.

1. Open Settings on Apple TV.

2. Go to Video and Audio.

3. Do any of the following:

• Set the video output format: Select Format, then choose the resolution, frame rate, and dynamic range settings for video playback.

• Turn on dynamic range matching: Apple TV can automatically switch the dynamic range setting during playback to match the dynamic range of the video content. Select Match Content, then turn on Match Dynamic Range.

• Check your HDMI connection: Apple TV can run a test to see if there are any problems with your HDMI connection. Select Check HDMI Connection, then follow the onscreen instructions.

• Recalibrate your display: If you’re having display issues, you can select Reset Video Settings to recalibrate your TV display.

Thanks and take care!

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Answer 3

AppleFan7512 Author

Level 1

12 points

Dec 30, 2022 12:09 PM in response to TammyW_03

Thanks for the suggestions, but my display has no bearing on this issue other than its reaction to the information it is being fed. This info is encoded in the Metadata that the ATV4K sends to the display. This will be consistent across displays and is reproducible on demand.

The issue is 2-fold.

The studio is not properly including the HDR metadata, specifically MAX CLL/FALL, in their stream info.
The ATV4K is applying a default MAX CLL/FALL of 4000/1000 to content with no MAX CLL/FALL metadata, which is way too high. Most content is going to be in the 1000/250 range.

Viewing the same content (such as Andor on Disney Plus) on an Nvidia Shield Pro 2019 will show you - -/- -, aka no value.

The issue is how Apple is handling HDR content that lacks metadata. It either needs to pass a null value or a default value more in line with a reasonless baseline.

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ATV4K HDR Metadata Max CLL/FALL

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