Slow/choppy playback with "30fps" sources from phone

(resolve 20 beta on Windows PC -- ARM laptop. Details in the link below)

I've been having trouble getting the editing page to provide reasonable playback in DR20 for one of my projects in particular. posted about that here:

viewtopic.php?f=40&t=218945

I've NARROWED THIS DOWN to a specific circumstance and wanted to ask if this is generally a known problem and/or whether you agree with ChatGPT's advice.

My project is set to 29.97fps for all timelines-- and the terrible perf is happening on any "30fps" source files shot on a Pixel phone (H265 Main L51)-- regardless of proxy type. Apparently pixel phones sometimes shoot variable frame rate and there's no way to force a constant frame rate in the phone camera. This does NOT happen for 29.97 source files.

I've tried this with:
- no proxies
- H264 proxies (full / half size)
- DNxRHQX (full / half size)
- DNxHR LB (full and half size)
- Optimized media (same as above)

No matter the proxy type-- bad stuttering occurs with these sources. Other sources are fine.

I asked ChatGPT if it's possible to set Resolve to some setting that forces the proxy FPS to 29.97 ... but it says you can't do that ... and it suggested that I re-encode all the source files to 29.97 with FFMPEG.

Do folks have thoughts/advice on this?
- is it a known problem in general that variable frame-rate soures are problematic in Resolve? (I don't recall hitting this in V19)
- do you folks know of a way to solve with proxies?
- do you think it's reasonable advice to re-encode with FFMPG?

thanks!

Variable frame rates are known to be a problem in Resolve. Lots of posts about it here. Surprised though that it still has a problem when using proxies.

It would be useful to know if reencoding at constant frame rate fixes it. Likely yes I’d think.

Slow/choppy playback with "30fps" sources from phone

What if you used a 3rd party program to convert the H.265 smartphone material to a constant-speed file format like ProRes 422 or DNxHR SQX? We've done it many times with iPhones and Androids, and it works fine. No editing program works well with variable-framerate source material.

Thanks ... I wasn't sure if re-encode OUTSIDE RESOLVE was known/recommended as the best/only solution and you all seem to be making clear that it does.

I did re-install Resolve v19 and confirmed that the bad stuttering happens there as well.

Question/suggestion: I think Resolve should handle the case of 'unusable' variable-frame-rate source clips, especially given that these are pretty common with modern smartphones.

Two options:

1) enable an option for proxy-generation as follows...

[x] Re-encode variable frame rate source clips to constant frame rate proxy files

2) Give an error/warning if proxy-generation encounters varianble frame-rate sources and suggest stopping the proxy-generation process.

It seems like it's at least somewhat common and would help editors/creators to normalize their content when they take the step to create proxies... kind of a bummer to spend the time creating proxies that are KNOWN to NOT PLAYBACK reasonably in Resolve. Especially since the phone camera apps *don't let you turn this off!*



thx

PS - I've posted sample media that exhibits the problem here: viewtopic.php?f=40&t=219373

Since most smartphones (all?) do variable frame rate, it would be great if Resolve could somehow deal with these clips.

For 'simple' videocreation you do not need a separate camera anymore. A good smartphone will do great. (a lot of potential users) Unfortunately smartphones do vfr.