Should I keep my video formats in .MOV or .MP4 for archiving?

I have converted old obsolete video codecs to H.265 a.k.a. HEVC video and AAC audio wrapped as .mp4 although .m4v is essentially the same, and also .mov should work just as well.

But I have also archived the old original movies because movie codecs are still evolving and better codecs might be available after 10-20 years.

Sadly movie metadata is still a nonstandard mess. I currently use "Keys" QuickTime tags because Apple's apps prefer them for date, location, title, author, description, and keywords.

marina28 wrote:

I think i'll convert to MOV 4K video. The "same as source" option seems to compress a lot, rendering smaller files and maybe lesser quality. Like a 300MB file goes down to 22MB. I don't feel very comfortable with that. Is that reduction normal?

I usually keep resolution and frame rate the same as in the original. The required bit rate and desired output file size varies much depending on the source quality and content. Talking heads HD resolution might be OK with as low as 1000 kb/s but footage with confetti, waves, poor lighting etc might need 10-20x or more for good output quality. Some encoders can keep the visual quality the same, for example in ffmpeg I often slightly overdo it with '-crf 18 -preset slow' while the default for H.265 is '-crf 28 -preset medium' with faster encoding and smaller output file sizes but then "difficult" footage might produce visual artifacts.