Castlevania - Symphony Of The Night -USA-.chd is a of the original PS1 game disc. It is designed for modern emulators like DuckStation, preserves all CD audio and game data, and can be created legally from a personal backup of the original BIN/CUE. Avoid it if you use older emulators like ePSXe or original PlayStation hardware.
The .chd file extension stands for .
The file size for Symphony of the Night in CHD format is typically around 366 MB , compared to the ~730 MB required for an uncompressed raw image. Castlevania - Symphony Of The Night -USA-.chd