> my Nvidia Shield devices won't play AV1

Put VLC on them. See if it works for your AV1 videos.

VLC also works on Apple TV: https://www.videolan.org/vlc/download-appletv.html

Yes. Deleting data does wonders for the filesize. The question I'm bringing up is one of quality.

If you must delete, delete starting from the 50GB+ original BluRays if at all possible, or some other very high quality source. That way the compression algorithm has the best chance of saving the important scene data.

And keep an eye on the known hard to encode scenes. A lot of the typical shots of a movie are handled well on one set of settings, but suddenly screw up on other scenes (or other animation styles. Anime vs Cartoons vs 3D vs Live Action can have subtle differences leading to quality issues).

It's not easy, and AV1 is our best bet at doing this well so far. But when the future algorithms come out, you need to start over from the best sources of you want AV2 to have a chance.

You should *Never* double compress. (Blu-ray -> H265 -> AV1). This is horrible for the quality. You'll get better results from BluRay -> AV1 by a large margin.

50GB gives assurances that the BluRays are high quality (but not always. I've seen some horrible BluRay encodings...)

As long as you are going from high quality sources, you should be fine. The issue is each transcoding step is a glorified loop-(find something we think humans can't see and delete it)

In other words: the AV1 encoder in your example works by finding 47GBs of data TO DELETE. It's simply gone, vanished. That's how lossy compression works, delete the right things and save space.

In my experience, this often deletes purposeful noise out of animation (there are often static noise / VHS like effects in animation and film to represent flashbacks, these lossy decoders think it's actually noise and just deleted it all changing the feel of some scenes).

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More importantly: what is your plan with the 50GB BluRays? When AV2 (or any other future codec) comes out, you'll want to work off the 50GB originals and not off the 3GB AV1 compressed copies.

IMO, just work with the 50GB originals. Back them up, play them as is.

I guess AV1 compression is useful if you have a limited bandwidth (do you stream them out of your basement, across the internet and to your phone or something? I guess AV1 is good for that) But for most people just working with the 50GB originals is the best plan

Yes, in general you find the best high quality source you can get your hands on and then compress that. For us lay people, that would currently be any 4k videos with a high bitrate. In such cases, it doesn't matter much that it is already compressed with AVC or HEVC. Sure, when you compress that again at a lower bitrate, there will some loss of data or quality. But honestly, it doesn't make a discernable difference (after all, you decide what is the video quality acceptable to you by choosing how much more to compress). Ideally, if DVD and Blu-Rays lasted long, we would all just be saving our videos on it. (Assuming there will be any Blu-Ray readers, 10+ years down the lane).

But then you look at flashback scenes and wonder where the noise has gone.

A lot of movies have purposeful noise, blurriness, snow, and fake artifacts to represent flashback scenes. One level of compression often keeps them okay-ish (like you can tell side by side that it's different, but only when you know what to look for). But these are the scenes that get especially ruined by two layers of compression.