Uncompressed Star Wars was 21 TB. However, it could be losslessly compressed to about a third of that size.
Regarding whether or not h264 is truly lossless, I did a quick test. I took a short, 3 second HD video and saved it as an uncompressed AVI. Then I took the uncompressed AVI and saved it with lagarith lossless compression as a new AVI file. I opened the new compressed AVI file again, and saved it as a third uncompressed AVI file. Using Hasher, I created checksums for both files. Both The original uncompressed file and the uncompressed lagarith file are identical:
Then, following the directions on the FFMPEG website for lossless encoding, I did the same thing. Here is the command I used to create the “lossless” file:
ffmpeg -i “q:\bombardier-captain-vincent-eva-Original.avi” -c:v libx264 -preset ultrafast -crf 0 “q:\bombardier-captain-vincent-eva-ffmpeg.mkv”
Then I took that MKV and resaved it as an uncompressed AVI. Comparing the hash values, it is clear that this is not the same file we started with:
I tried it again using Handbrake, and the checksums still didn’t match.
QED h264 is only visually lossless. Unless you can uncompress it and get the exact same file you started with, it is not truly lossless - just like with winzip or winrar - you should be able to get back the exact same file you put into it. If you can’t, then you lost something.
EDIT: This is probably due to a behind the scenes color space conversion: Uncompressed RGB -> YUV420; But if it can only losslessly compress data in the same color space that’s pretty limiting.
My preferred lossless codec is MagicYUV (https://www.magicyuv.com/) because it is very fast and can losslessly save even 10-bit+ color formats.