Discs as time capsules: Chapter II

Warning that this may be my longest blog post thus far.

This feels like I'm playing the data storage equivalent of Inventory Tetris.

So far, the directory I'll put on the disc contains:

• A ClassiCube server containing my VRChat recreations, losslessly compressed with 7z
• Emulator save states & screenshots, because I recently beat Cotton 2 and Panorama Cotton
• (incomplete) Minecraft skins, losslessly compressed with oxipng
• Minecraft worlds from 2017 to 2023, losslessly compressed with 7z
• Minetest worlds, losslessly compressed with 7z
• Nintendo 3DS save data thanks to Checkpoint 3DS, losslessly compressed with 7z
• Nintendo GameCube save data from Dolphin, losslessly compressed with 7z
• Nintendo Wii (NAND) save data, including one from an older disc, losslessly compressed with 7z
• Super Mario Bros. X 1.2.1 save data, as a throwback to an older disc

Compression is the name of the game. The best gains I've got were from compressing my ClassiCube server from 94.4 MiB to 2.9 MiB, and a Minecraft world that was available for download before a server shut down, from 7.1 GiB to 311.4 MiB. I considered ZPAQ as an option but that'd take forever.

But so far, I'm trying to add more. DVDs are 4.7 GB. 4 GB is already filled; now I need to fill the extra 700 megs with something.

I've actively considered adding my Minecraft and VRChat screenshots to the disc, especially since they reflect recent memories with new friends and aren't as heavy as my recordings. On one hand, that sounds great. On another hand, all Minecraft screenshots take 3.3 GiB, and VRChat takes 1.5 GiB. Not even oxipng can help with that. We don't have that time of space!

Well, a sacrifice has to be made: I'm gonna compress them lossily (but keep the lossless ones on my drives; remember, this is a backup of a backup!). For a test run, I used ImageMagick's mogrify command with -format jpeg, -format heic and -format avif, no other arguments other than the source files.

• Source (PNG) comes in at 1.5 GiB
• JPEG comes in at 258.4 MiB
• HEIC (based on HEVC) comes in at 80.6 MiB
• AVIF (based on AV1) comes in at 26.4 MiB. Holy ravioli, Mario.

Of course, being lossy, there's a penalty to all that gain. Here it is tested on one screenshot:

Plus, using XFCE, the native file manager (Thunar) and image viewer (Ristretto) don't support the formats. So I guess that gives me another reason to switch to KDE. I'm currently eyeing AVIF despite its utter destruction because the whole point of this is to preserve memories, not every pixel, and some of my 4K screenshots hog up space even with JPEG.

Not sure what command to use to burn the disc, either. Since I use Linux, I expect to use wodim:

• genisoimage -J -joliet-long -r -o disc1.iso -V "Checkpoint 2023-09-07" <sourcedir>
• wodim <file>.iso

EDIT (2023-09-07): Okay so I got a little overboard with the compression, so I used AVIF. I made sure to fit as many screenshots as I could, including PS4/PS5, Steam, and Switch. ~4.4GB (4.1 GiB) has already been used, which would probably be much more if I was using HEIC.

Also, I learned after mounting my ISO that I have to add -J -joliet-long -r so it doesn't cut my filenames down to what looks like DOS filenames.

EDIT (2024-09-13): A year later, I feel I've been pretty harsh on AVIF. AV1 is a pretty damn good video codec and there have been projects like SVT-AV1-PSY built to minimize artifacting. ImageMagick's defaults for AVIF aren't the best.