After playing an HDR video on iPhone for a while, the HDR effect disappears and the screen brightness decrease

Question

Created 1w

Replies 4

Boosts 0

Participants 1

When i use AVPlayer to obtain the video frame CVPixelBufferRef of an HDR video, and use AVSampleBufferDisplayLayer to display it on the screen, after a period of time, the HDR video content and screen gradually darken, losing the HDR effect.

Steps to reproduce:

Create an AVPlayer to loop an HDR video, specify the video frame format as kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange
Create a timer to get the video frame CVPixelBufferRef at 30 frames per second
Use AVSampleBufferDisplayLayer to display CVPixelBufferRef on the screen
Don't operate the phone, wait for a period of time (such as 40 minutes), the HDR effect disappears and the screen darkens

Note:

You need to use an iPhone device, iOS 18.5 and below operating system
You need to ensure that the HDR video is played in a loop, that is, to ensure that the screen continues to display HDR content, wait for a period of time, depending on different devices, you need to wait for 20-40 minutes.
In the iPhone Photos app,the same problem will occur after playing HDR video in a loop for a long time

Expected Results:

When rendering HDR content for a long time, it is guaranteed that there is always an HDR effect, and the HDR content and screen will not be darkened.

Current Results:

After about 20-40 minutes, the HDR effect disappears and the screen darkens.

Boost

Answer 1

mengkeer OP

1w

Why does it work fine on iPad devices, such as iPad Pro 12.9-Inch 5G, but not on any iPhone?

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Answer 2

mengkeer OP

11h

I provided my test project in the bug report FB18502486.，

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Answer 3

mengkeer OP

11h

My question is why in my iPhone (eg iPhone15, iPhone 12 Pro, etc..), when i loop an HDR video in Photos APP or display HDR content on the screen via AVSampleBufferDisplayLayer, just wait after 20-40 minutes, the display will dim and the current EDRHeadroom will be reduced gradually, and the operating system will tonemap it to SDR. However, this issue does not occur on the iPad.

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Answer 4

mengkeer OP

11h

Note： the screen brightness don't decrease，but as as the current EDRHeadroom is reduced, the display will gradually dim, and the HDR content will eventually be tone-mapped to SDR by the operating system.

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