Audio.Quote:

typedef struct ADB
{
	char	Header[12]; //LhCoMpReSsEd always
	DWORD	Unknown; //number of files?

} ADB;

typedef struct ADBEntry
{
	DWORD	sizeDecompressed; 
	DWORD	sizeCompressed; 

} ADBEntry;

Zlib compressed. After Decompression file assumes ADB header. except header becomes "LhBiNaRy####" and the unknown DWORD appears to be the same value.

Quoted from Silver from another forum, link. There's other useful info in that thread too.