[drewtato]

This depends on how much time you want to spend. If you want the transcode to take less time than the playtime of your videos, it'll probably be best to just use the best hardware encoder you have with high quality settings.

If you have more time, then AV1 is good. Read through the trac page [1] and do test encodes with 5-10 seconds of video to determine what settings give you your desired quality. Note that low `-cpu-used` or `-preset` values will give great quality but take incredibly long. Then, encode a few minutes of video with various settings to determine what settings give you your desired file size.

For human time usage, keep track of the commands and options you use and how those affect the output. If the job will take more than a few hours, write your script to be cancellable and resumable.

[1]: https://trac.ffmpeg.org/wiki/Encode/AV1