After-Render, Playback in Quicktime at Lightning speed

Hello everyone.
Having rendering output issues here.

After I Render, and I want to see it in Quicktime, my 30-second video plays in 3.4 seconds!
WAY TOO FAST.

What happened? It was working fine yesterday. Kept my mac on all night, opened up my project, and now I cannot see the results after a new render because the resulting output of both .mov and .mp4 formats play SUPER FAST in Quicktime.

I checked the Master Settings and all is set to Automatic. (I have never touched that area)
I am using the standard Youtube settings for rendering- I did not change any defaults. All I did was a few minor edits this morning, and now I cannot use the file.

Hardware:
2020 Imac, running latest OS: Mac OS Big Sur 11.4
3.6 GHz 10-Core Intel Core i9
Graphics card: MD Radeon Pro 5700 XT 16 GB

Project info:
Default Youtube Render (made no changes - I usually always leave this alone, and it renders beautifully - except for today.)
Project frame rate: 24
Format (either .mov or .mp4)
Codec: H.264

I tried to attach the final output video .mp4 file so you can see what I mean, but it appears that I cannot attach the file because it is too large. ,:(

Is there something I am missing? Is it Quicktime? No clue. Wondering if you see the same results as me.
Thank you so much in advance for your help.
- Edie

I have seen some wierness like that before.
Close Resolve and then try and play the clip.
In my case that solved it. So some sort of GPU driver thingy wierness.

[Peter Chamberlain]

Moved to Resolve forum

QuickTime and Windows Media Player are two of the worst media players out there.

Try VLC instead. Report back.

QuickTime and Windows Media Player are two of the worst media players out there.

Try VLC instead. Report back.

VLC WORKED. omg, thank you.

I have seen some wierness like that before.
Close Resolve and then try and play the clip.
In my case that solved it. So some sort of GPU driver thingy wierness.

I used VLC instead of Quicktime to fix the problem. Thank you so much for your suggestion.

https://9to5mac.com/2019/07/29/macos-fa ... iod-video/