Regarding the need to convert older personal videos in Photos app before doing an OS upgrade

There is every need to do it before upgrading from Mojave to Catalina . Some videos need older 32-bit frameworks, that are no longer included in macOS 10.15 Catalina or later. Once we are running Catalina, we will need third-party software to be able to convert legacy media, that are no longer supported on Catalina.

Some potentially problematic video codecs are listed here: About incompatible media in iMovie for macOS - Apple Support

Greetings Snickers513, 

In the Photos app on Mac, in the side bar under the Albums heading should be folder called Videos. Do you see that there? If so, it should have all your videos in one place. You can then convert what you’re wanting/needing.

You should be able to see a screenshot in the following link where it shows, in the side bar, Albums, then a subsection for Media Types and then an option for Videos. What are albums in Photos on Mac?

Can you tell us more about what format you're wanting to convert the videos to prior to installing a macOS upgrade?

Thanks. 

Snickers513,

It looks like the direction in the above article is for after you upgrade to Mojave. There wouldn't be a need to convert before upgrading since you'll be able to see what videos need to be converted once you've already upgraded to Mojave. Once converted in Mojave, they'll stay relevant for future upgrades.

We do suggest ensuring you have a backup of your data before upgrading your software. Here's how to back up: Back up your Mac with Time Machine. You can find the link to upgrade to Mojave here: How to download macOS.

Cheers!

I tested my videos by importing them into a new Photos Library.

• Export all videos from Photos with File > Export > Export unmodified original
• Then drag them in small groups into new Photos Library. Any problematic Video will give a warning.
• Remove it from your main library, then reimport the converted version.

My biggest problem are the older versions of videos embedded in Keynote an PowerPoint presentations. They are much more difficult to search and to check. I have kept an older Mac on Mojave, so I can fix old lecture notes on my old Mac, when I come across embedded videos that no longer are able to play.

I have converted all movies that either failed to play on various versions of iPhoto/Photos. Or failed to sync to an iPad Pro (1st generation 2016. At one point movies without an audio track failed to sync but that has been fixed now) or fail to play correctly there (many old cell phone movies with obsolete codecs or .avi wrapper. 10-bit HDR/HLG movies must be converted to SDR on that oldish iPad).

Yes, Mojave does warn about incompatible media and Monterey insists H.265/HEVC to have Codec ID hvc1 instead hev1 (can be fixed losslessly with ffmpeg) but it does not anymore complain about Chroma subsampling 4:2:2 (Bit depth 10 bits) like Big Sur did.

I checked all those issues practically one-by-one by saving Photos-to-iPad sync error logs or noticing which movie macOS or iOS complained. I often also used Invisor to filter out similar movie/audio codecs or exiftool to filter out similar devices which had captured those movies.

https://www.invisorapp.com/

https://exiftool.org/

What a nightmare. 😲

You're welcome, Snickers513 😊