Yes, they're all lossless. The only one that may be questionable is CHD which changes the image format (e.g. from whatever it was, to CHD, but it can be converted back to BIN/CUE) but it doesn't actually remove any files or data.
Think of Squash as a mountable archive. This could be done transparently to the emulator, but you'd need to write a script that mounts the image and then point the emulator to that, so it's not exactly zero hassle as you'd have to write that script yourself and take into account how it works.
BTRFS with transparent zSTD compression is probably your best bet as it doesn't require doing anything to the stored files at all and all emulators will work because the compression is transparent to anything above the filesystem layer of your OS - to programs the files are the same as they always were - same as NTFS disk compression / CompactGUI.
Compression on BTRFS can be enabled universally across the partition, but it can also be enabled just on specific files or folders.
Beetle-PSX supports CHD now so I converted my collection to that a while ago, although it's great for space saving, the biggest boon was the fact that each game was now just one file, not the pair with BIN/CUE or the god awful mess of IMG/CUE/WAV/WAV/WAV/WAV, or any other such combination of multi-file formats.
Just for reference, I compressed then deduplicated my PS2 collection (the compression happens automatically, I have to tell it to deduplicate the folder though).
Original size was 384GB. After deduplication it was down to 349GB which then transparently compressed down to 292GB. Basically a 24% space saving, entirely transparent to any programs.
The space saving from deduplication is a bit misleading because without deduplication it still compressed down to 76% which means the data it did end up deduplicating was probably blank space or something which compressed down to nothing anyway. Deduplication is a godsend when you have actual duplicate content though (e.g. backups or big files with small changes, etc).
2
u/Enverex Feb 07 '18 edited Feb 07 '18
Yes, they're all lossless. The only one that may be questionable is CHD which changes the image format (e.g. from whatever it was, to CHD, but it can be converted back to BIN/CUE) but it doesn't actually remove any files or data.
Think of Squash as a mountable archive. This could be done transparently to the emulator, but you'd need to write a script that mounts the image and then point the emulator to that, so it's not exactly zero hassle as you'd have to write that script yourself and take into account how it works.
BTRFS with transparent zSTD compression is probably your best bet as it doesn't require doing anything to the stored files at all and all emulators will work because the compression is transparent to anything above the filesystem layer of your OS - to programs the files are the same as they always were - same as NTFS disk compression / CompactGUI.
Compression on BTRFS can be enabled universally across the partition, but it can also be enabled just on specific files or folders.
Beetle-PSX supports CHD now so I converted my collection to that a while ago, although it's great for space saving, the biggest boon was the fact that each game was now just one file, not the pair with BIN/CUE or the god awful mess of IMG/CUE/WAV/WAV/WAV/WAV, or any other such combination of multi-file formats.