herein2021
Well-Known Member
I think all of the online platforms re-encode everything. In most cases, they encode several different copies with different data rates and resolutions, then match them to the bandwidth they sense going to the viewer system. That’s why it’s so important to upload as lightly compresses a version as your upload bandwidth will allow. I usually upload a 25Mbit h.264 file to Vimeo or YouTube, but occasionally, if quality is especially important, I’ll upload a ProRes file. Their compressed streaming files look a bit better. (Or at least they do in my so-called mind. ?)
Oh I agree, they actually create usually up to 12 different formats. I once tried to host all of the formats on my own web server to accommodate the native formats for Android, Apple, Windows, cell phones, tablets, desktops, then 4K monitors and it was nearly impossible. All of the platforms transcode but there are tricks to getting the best quality.
For example, YouTube uses a higher quality codec if you upload a video with at least 2K resolution, they will also give you better results if you stick to 16:9 aspect ratios, etc. The sweet spot that I have found is to shoot at 4K30 or 60FPS in H.265 edit on a 1080P timeline so that I can recompose in post, then upscale to 2K prior to uploading to YouTube to get the better codecs.