Rendering issue

First, I am not a professional, don’t shoot me if I say something silly

I am editing a 5 minute clip. I found that the rendered clip has unintended flickering occasionally. It is pretty random that it hit different places in different attempts. The issue occurs in both 1080 and 4K output. I tried to separate the video clips on one Samsung T5 SSD and output clip on a Sandisk Extreme Pro USB. It is better but still happens. Any idea?

My computer is 5 years+ old 2x8 cores Xeon E5-2630 2.4GHz, 128GB RAM and Vega 56.

We need to see the flicker.

I trimmed and uploaded the portion with issue.

When the word "flicker" is used, I think of rapid changes in brightness. The flicker we see here is a rapid movement of the entire scene.

Possibilities I can think of:
-- A wayward optical image stabilization in the lens/camera. You can exclude by reviewing the source footage.
-- DR optical image stablization went crazy. Exclude if you didn't use it.
-- A stray keyframe if you used the Edit pages Transform panel to pan.

The source is pretty clean. Here is the desktop recording of the playback using Resolve. Also transform is not used at all.

If you used a compressed format like h.264 or h.265, try a mezzanine format like DNxHR to see if this shows up.

If you used GPU-accelerated encoder, try Native.

OK.

I would call that more of a glitch than a flicker. Potential causes may be poor quality footage, from a cell phone for example. Or a frame rate mismatch somewhere in the pipeline.

I did a few experiments using different combinations. Now I am able to replicate the issue consistently.

The video clips were taken by Sony mirror-less camera, 4k/30fp/HLG and I believe it shouldn't be an issue. BTW, Resolve 16.x cannot process iPhone video clips in the moment, at least some of my samples. This is confirmed by the support team.

With similar number of clips on the timeline, when I set a video clip to reverse playback, the rendered video will 'shake'/'flicker'/glitch (whatever you would like to call it ). When I revert it to normal playback and render again, the rendered video becomes normal. I repeated the process a few time, the result is very consistent.

Any advice? Thanks.

One thing I've seen suggested is to use a free program called Shutter Encoder to transcode your cell phone footage to an editing codec like DNxHR or ProRes.

And transcoding compressed codecs to an editing codec may help with playing it in reverse. Maybe someone else has a better idea.

If you decide to try transcoding, please let us know how that works out.

Hi Michael, thanks for the suggestion, will try it later.

I have just quickly installed v15.3.1, recreated the entire project using same set of clip, reversed a few clips and render the video. Everything is good now.

I think I will stay with v15 as it works fine with iPhone clip too. The 'cut' page is great and performance of v16 is better but I can live without these as an non-professional user.

Tried 16.1.2, same issue.

Have you checked frame rate closely?

Tried 6.2, same issue.

Hello! Same issue. Did you find a solution of these?