Great question—let’s break this down clearly, since your two questions are really two sides of the same coin. FitGirl’s ability to shrink a 50GB game folder down to 30GB (or even more extreme ratios) isn’t magic—it’s a combination of smart file optimization, targeted algorithm use, and leveraging the unique structure of game files.

Core Compression Principles #

FitGirl’s process revolves around eliminating waste and matching the right tool to each file type:

• Redundant File Removal: Most commercial game install packs are bloated with duplicate files. Think multiple copies of the same texture across different language packs, repeated audio clips, or identical configuration files. FitGirl’s scripts scan for these duplicates, keep only one copy, and rebuild them during installation. This alone can shave off 10-20% of the total size in many cases.
• Type-Specific Compression: Not all files compress the same way, so FitGirl doesn’t use a one-size-fits-all approach:
  • For pre-compressed game assets (like .pak, .bin, or .dat files that already use Zlib/LZMA), she’ll often re-compress them with higher LZMA2 parameters (slower, but more efficient) instead of just leaving them as-is.
  • For uncompressed media (raw audio, unoptimized textures), she uses visually/audibly lossless compression. For example, using FFmpeg to re-encode background music with efficient codecs at bitrates that don’t degrade quality, or converting textures to more space-efficient formats (like optimized DDS) that the game can still read natively.
• Pack Structure Optimization: Files are grouped by similarity before compression. This lets the compression algorithm’s dictionary (the part that identifies repeated patterns) work far more efficiently—similar files share more patterns, so the algorithm can compress them into smaller chunks.

Tools & Algorithms Used #

FitGirl relies on a mix of open-source tools and custom scripts to pull this off:

• 7-Zip (LZMA2 Algorithm): This is the backbone of most lossless compression. She cranks up 7-Zip’s parameters (larger dictionary sizes, more compression passes) to get maximum ratio, even though this makes compression/decompression much slower.
• FFmpeg: Used to optimize audio and video files without perceptible quality loss. It’s perfect for trimming unnecessary bloat from game cinematics or background tracks.
• Custom Batch Scripts: These automate the entire workflow—scanning for duplicates, sorting files into compression-friendly groups, calling the right tools with the right parameters, and building the final install pack. Without these scripts, manually optimizing every game would be prohibitively time-consuming.

To directly answer your 50GB → 30GB example: that 20GB reduction likely comes from ~10GB of redundant files being removed, plus another 10GB from aggressive LZMA2 compression and media optimization. The tradeoff? You’ll spend way longer installing the repack than a standard game, since the installer has to decompress high-ratio files and rebuild all the redundant content.

内容的提问来源于stack exchange，提问作者user12425978