During the 2000s, video game developers utilized standard 4.7 GB DVD-ROMs (or 8.5 GB Dual-Layer DVDs) for retail distribution. Even if a game only contained 800 MB of actual assets (code, textures, audio), developers filled the remaining gigabytes with "dummy data" or padding files. This padding pushed data to the outer edges of the physical disc, which optimized laser reading speeds on the physical PS2 console hardware. How Modern Compression Works
Once complete, delete the large original ISO files from your PC. Move the newly created .chd files to your Android device via USB cable or wireless transfer. How to Setup and Run Compressed Games in AetherSX2 aethersx2 games highly compressed