There's no doubt that things can get a bit confusing regarding non-integer frame rates -- a decimal-specific frames-per-second count isn't exactly an intuitive aspect of video. Of course, beginners can't learn such distinctions if they're going unspecified -- a fact Vimeo has recently (and finally) addressed in updating their compression guidelines. Even more importantly, Vimeo is slowly but surely raising the quality ceiling in its encoding of your media -- albeit in audio-only, in this case.
Get Specific With Specs
The worst thing for someone still learning the ropes of digital video is when the video services around them glaze over the specs -- 24 is different than 23.976 -- and if you want the best possible control over the quality of your media (which you probably do), understanding such details is important. As ProVideoCoalition points out, Vimeo's compression documentation now includes the non-integer cousins of actual whole-number frame rates. Both types were always supported in its encoding ("same as source"), but in a world of potentially confusing number-letter combinations, being specific is healthy. It also avoids rounding (i.e. referring to 23.976 as 23.98), thankfully -- the less confusing this stuff has to be, the better -- and just calling it what is simplifies everything.
The guidelines now properly state support for 23.976/24, 25, and 29.97/30 frames per second. Videos of higher frame rates are recommended to be halved in encoding -- for instance, 60p would be encoded at 30 frames per second.
Up the Audio Ante... Above CD-Quality (Finally)
Bizarrely (and kind of horrifyingly), Vimeo indicated 44.1 kHz as the sample rate at which to encode your audio. 'Bizarre' because 44.1 kHz is the sample rate of the 30-year-old Compact Disc audio spec, and at this point, virtually no other surviving tech. When your cellphone can accurately sample a far greater frequency range than any CD you own, it may be about time to get with the program. Says PVC:
At first, I had hoped that Vimeo’s recommendation for 44.1 kHz was (like the non-integer framerate explained above) just a question of mis-documentation, but in the case of the audio sampling, that was not the case. Vimeo was unnecessarily resampling 48 kHz down to 44.1 kHz, which made me cringe. Fortunately both issues were quietly fixed. Now Vimeo is recommending 48 kHz, and only recommends uploading a lower sampling rate in case the original source is (for some reason) lower. Thank you Vimeo!
Amen to that. A higher fidelity allowed doesn't mean your media necessarily sounds better, unfortunately -- but being limited to ancient numbers is akin to shooting yourself in the foot before you even put your shoes on. I too, Vimeo, thank you for this update -- though I am a little sad for every video uploaded before it, which I can only assume will retain the old sample rate.