| Format | Compression Ratio | Speed | Emulator Support | Best For | | :--- | :--- | :--- | :--- | :--- | | CHD | Excellent (20-60% of original) | Very Fast | PCSX2, RetroArch, MAME | PC / Steam Deck | | CSO | Good (30-70% of original) | Medium | AetherSX2 (Android), PPSSPP | Android phones | | Zstandard (ZST) | Excellent | Fastest | Newer PCSX2 nightly builds | High-end PC | | 7z | Best (10-50% of original) | Slow (Decompression) | Not direct play (must extract) | Archival storage |
Verdict: For playing directly, use CHD. For archiving on a hard drive, use 7z with Ultra compression.
| Method | Description | Typical Size Reduction | |--------|-------------|------------------------| | Lossless compression (CSO, ZSO, CHD) | Compresses disc image without removing data. | 20–40% | | Lossy compression (audio/video re-encoding) | Downgrades FMVs (Full Motion Videos) and audio bitrate. | 40–70% | | Downgrading DVD9 → DVD5 | Removes or compresses extra language tracks, high-res videos, or unused assets. | Up to 50% | | Rip / “Undub” versions | Removes dubbing tracks, retains Japanese audio only. | 10–30% | | Removing dummy data | Many PS2 games had filler data (to speed up disc reading); stripping it shrinks size without quality loss. | 5–25% |
Example: God of War (original DVD9: ~8.5 GB) can be compressed to ~1.2 GB by reducing FMV quality and removing extra audio.
A "high compressed PS2 game" refers to a game file that has been reduced in size significantly below its original DVD capacity (4.7GB+) using advanced archiving techniques. high compressed ps2 games
High compression usually refers to CSO compression level 9 or 7z Ultra settings using the LZMA2 algorithm. Some games compress incredibly well (e.g., Ico—3 GB to 200 MB) because the game contains vast amounts of repetitive texture data or FMV cutscenes that compress easily. Others (Gran Turismo 4) compress poorly because the data is already encrypted or randomized.
If you own original PS2 discs:
Result: You get a small file without losing FMV/audio quality.
Step 1: Rip your disc.
Insert your PS2 disc into your PC DVD drive. Use Imgburn to "Read image to disc" – save as an .iso file. | Format | Compression Ratio | Speed |
Step 2: Download CHDMan.
Get the latest chdman.exe from the MAME development site or use the built-in tool in PCSX2 nightly.
Step 3: Run the compression.
Open Command Prompt in the folder containing chdman.exe and your ISO. Type:
chdman createcd -i "game.iso" -o "game.chd" -c cdzl
Pro tip for "High" compression: Add the -cc zstd flag (if using newer CHDMan) for the highest ratio:
chdman createcd -i "game.iso" -o "game.chd" -c zstd:lzma:cdzl
This applies three layers of compression (Zstandard, LZMA, and CDZL), shrinking games by up to 75%. | Method | Description | Typical Size Reduction
“For RPGs like Final Fantasy X or Persona 4, high compression works fine — you lose some FMV quality but gameplay is fine. For racing or action games like Burnout or Ratchet & Clank, avoid it — streaming audio and fast loading suffer badly.”
“CSO level 9 saves space but makes PCSX2 hitch every 5 seconds on my laptop. Level 5 is safer.”
“Downloaded a 150MB ‘Shadow of the Colossus’ — turns out it was just the intro and first colossus, then infinite loop.”
Downloading a compressed game is just the first step. To play it, you usually need to extract the file first.
Tools You Need:
The Process: