Re: [Bug-xorriso] Mode 1/2, Form 1, XA, XA1, etc

[Thomas Schmitt]

Hi,

> Mode 1/2, Form 1, XA, XA1, etc
> whats the difference between these modes and when are they used?

They apply only to CD, but not to DVD or BD media.
Definition is in SCSI/MMC specs, e.g. MMC-1,
4.1.4 CD-ROM Sector Formats.

xorriso supports only Mode 1 = 2048 bytes of payload.
All control fields and checksums are filled by the burner
drive. (A raw CD sector has 2352 bytes.)
Mode 1 is equivalent to the only write mode of DVD and
BD media.

cdrskin also supports CD Digital Audio, which puts payload
into all 2352 bytes of the CD sector.

Mode 2 is a format with 2336 bytes of payload. I know
of no example where it would be used.

CD-XA is a pair of formats. Form 1 is for 2048 bytes data,
quite similar to Mode 1. Form 2 is for 2324 bytes without
checksum. E.g. video or audio, where a little glitch does
not harm the whole show.
This was obviously used for the special CD types which
were in use for multi-media content before DVD washed
them all away.

libburn has code for Mode 2 and CD-XA. But i never tested
it because i have no test cases. No CD video player,
not even a CD audio player.


> Is it possible to burn multiple sessions with different modes and
> does it make sense at all?

It is prescribed that mixed mode CD shall use CD-XA.
Thus cdrskin refuses to put CD Digital Audio tracks
and Mode 1 tracks onto the same medium within the
same session.
(I'm not sure what it does if you want to add a
 pure data session to pure audio session.) 


Have a nice day :)

Thomas