Flickering problem on the video screen after using RIFE frame interpolation

[qingchunyy]

When using RIFE frame interpolation (with 3x interpolation factor), every 3rd frame appears brighter, causing noticeable flickering during playback. It seems these brighter frames might be the original video frames. What's causing this phenomenon?

[k4yt3x]

Is your video HDR by chance?

[qingchunyy]

No, my video is BDMV

ID : 4113 (0x1011)
Menu ID : 1 (0x1)
Format : AVC
Format/Info : Advanced Video Codec
Format profile : [email protected]
Format settings : CABAC / 4 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 4 frames
Format settings, Slice count : 4 slices per frame
Codec ID : 27
Duration : 1 min 32 s
Bit rate mode : Variable
Bit rate : 36.4 Mb/s
Maximum bit rate : 40.0 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.732
Time code of first frame : 00:59:59:00
Stream size : 399 MiB (90%)

[qingchunyy]

[k4yt3x]

@wondent please add your information here.

[cosmito-lab]

I also get the same kind of flickering on one video (not HDR) when using 2x interpolation, model 4.26

[lossless-debug]

Reasons/ideas how to fix? e.g. First part of video is well, second part has flickering (fully black frame, well frame, ...).
Edit: 4.25 Lite has no flickering on same video, but 4.6, 4.25, 4.26 have.
Edit 2: 4.25 Lite has flickering too, but rarely. 4.26 has less flickering than 4.25 or 4.6
PS: I suspect that the 'Scene Detection Threshold' parameter somehow affects the flickering.

[avan06]

I saw a similar issue in the ECCV2022-RIFE project.
The author of the RIFE model believes that the algorithm itself does not have a strong tendency for color shifts.
It might be related to video frame reading and writing.
I'm not sure if this brighter frames issue is caused by the same reason.
You may also refer to it for further insights.

hzwer/ECCV2022-RIFE#350
hzwer/Practical-RIFE#120