Sub-headers

vbimport

#1

Can anyone tell me how the sub-headers are written in the CD-XA form 1 and form 2 is written? I know so far that the sub-header is in fact only 4 bytes long and that the next four bytes are duplicates… but what information does it hold? how can I distinguish a mode 2 form 1 sector from a mode 2 form 2 sector without having to analyze the sectors structure to do it?

Can anybody help me out with this?


#2

As far as I know the only way is to analyze the sector to tell a “form 1” from a “form 2”. Lucky for us the MMC2 draft (pg 47) has a brief specification of the subheader. In particular bit 5 of the sub-mode byte will tell you that.


#3

where can I find the mmc2 draft? from t10?


#4

well… I found a website that seems to have the description of what the sub-headers are used for, it’s in German though, but I did the best translation that I could, here is the translated text:

Byte		Use
 1 	Identification of interlocked files (00 when not interleaved) 
 2 	Channel Number
 3 	Submode Byte
		BIT 7: Signals End of File (EOF)
		BIT 6: Signals if Data is dependent on time
		BIT 5: Signals if sector is Form 1 or Form 2
		BIT 4: Type on (depends on the Operating System)
		BIT 3: Data Sector		-\
		BIT 2: ADPCM Audio Sector	- |--> Identification for the type of data found in the sector
		BIT 1: Video Sector		-/
		BIT 0: Signals End of Record (EOR)
 4 	Type of Coding for the Video and Audio data (00 when data sector)
 5-6	Copy of the last 4 bytes (for data security)

I’m not quite sure about what the first byte does, that frase is taken directly from babelfish, without any editing done by me, becuase I am not sure what it is trying to say, BIT 4 is also a translation done by altavista’s babelfish and I am not sure of what it is supposed to mean… Can anyone shed some light on this subject?

btw, here is the site that i got the info from: http://www-is.informatik.uni-oldenburg.de/~dibo/teaching/mm98/buch/node113.html#SECTION04923000000000000000


#5

Yep: http://www.t10.org
and go into SCSI-3 architecture.

But it’s pretty much what you have found in the German.


#6

what’s the difference between the final drafts that they have on the site and the final documents that they publish? are there that many differences to the standard?


#7

I’m not sure myself, I don’t have the final standards. The draft seems to be adequate for making a working tool.