{"id":491,"date":"2007-11-20T20:52:14","date_gmt":"2007-11-21T04:52:14","guid":{"rendered":"http:\/\/multimedia.cx\/eggs\/iso-compromise\/"},"modified":"2007-11-20T20:52:14","modified_gmt":"2007-11-21T04:52:14","slug":"iso-compromise","status":"publish","type":"post","link":"https:\/\/multimedia.cx\/eggs\/iso-compromise\/","title":{"rendered":"ISO Compromise"},"content":{"rendered":"

Engineering is about trade-offs and compromises. One of the most fundamental trade-offs to be made when designing a storage format is whether multi-byte numbers will be encoded as little or big endian numbers. But have you ever studied the data structures involved in ISO-9660, the standard filesystem format for optical discs? It seems that the committee tasked with developing this standard were unwilling to make this one tough decision and specified all multi-byte numbers as omni-endian<\/strong>. I just made that term up. Maybe it could be called bi-endian or multi-endian. The raw detail is that multi-byte numbers are stored in little endian format and then<\/em> in big endian. For example, 0x11223344 is stored using 8 bytes: 0x44 0x33 0x22 0x11 0x11 0x22 0x33 0x44.<\/p>\n


\n\"CD-ROM\"
\n<\/center><\/p>\n

Do any other filesystems take this compromise? I am not that versed. I have studied the odd game-related optical filesystem; I had to write a manual ext2 searching tool for a sysadmin class; I also had to try to recover a virus-corrupted FAT16 filesystem (to no avail; that virus cleanly chewed up some of the most important sectors).<\/p>\n

Anyway, if I were to go ahead and try for a new FUSE<\/a> driver for ISO-9660 (or modify an existing driver), I would want to go after the main format. Plus, I would want to natively interpret that CISO format<\/a> on the fly. Further, I would use this as a platform to understand what is so special about the apparent ISO-9660 data ripped from a Sega Dreamcast GD-ROM.<\/p>\n

Are there any other ISO bastardizations to target for such a tool?<\/p>\n","protected":false},"excerpt":{"rendered":"

Engineering is about trade-offs and compromises. One of the most fundamental trade-offs to be made when designing a storage format is whether multi-byte numbers will be encoded as little or big endian numbers. But have you ever studied the data structures involved in ISO-9660, the standard filesystem format for optical discs? It seems that the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[91,69,97],"class_list":["post-491","post","type-post","status-publish","format-standard","hentry","category-programming","tag-ciso","tag-dreamcast","tag-iso-9660"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t