I was surprised to see some data CD-ROM's created as "CD-XA" containing one track of mode 2 form 1, instead of the normal mode 1. Why would it be made that way? The CDR FAQ (http://www.cdrfaq.org/faq02.html#S2-43-4)says "Mode 2 extends the definition of a Mode 2 CD-ROM. Form 1 looks like a slight rearrangement of a Mode 1 sector, with the 8 bytes of space moved ahead of the user data and filled with a sub-header." Is this sub-header used for anything interesting? Is Mode 2 Form 1 better than Mode 1 somehow, other than for getting around the restriction of mixing modes on one disc? --John
If you read http://www.disctronics.co.uk/technology/cd-rom/cdrom_spec.htm#Mode 2 Sectors you can see that Mode2Form1 is almost identical to Mode1, except for 8 bytes that are unused in Mode1 and used as a 'subheader' for Mode2Form1. I assume info in the 'subheader' specify if the sector is Form1 and Form2. -------------------------------------------------------------------------- Quoting from disctronic's web site: " Note that Mode 1 and Mode 2 Form 1 use the same error correction so can be used interchangeably, but not within the same track and preferably not on the same disc. Software used to write CD-Rs can be set for Mode 1 or Mode 2 Form 1. Almost all PCs and Macs will read Mode 2 Form 1 CD-ROMs as well as Mode 1 " -------------------------------------------------------------------------- So you understand that Mode1 or Mode2Form2 are more or else the same, with the exception that CD-XA (extended architecture, DATA+AUDIO) are always burned in MODE2 datatype.
