Hello Mike,

MB> Restricting the discussion to conventional CD-ROM, which is a different 
MB> format from Red Book audio, there are two recording modes known as
"Mode 1" 
MB> and "Mode 2," which have different "long" sector
lengths, 2352 and 2340 
MB> bytes.  Some older drives only support Mode 1, but all modern drives also 
MB> support Mode 2.

Yellow-Book

mode 1 ( data only )
Sector Sync -   12 bytes
Header      -    4 bytes
User Data   - 2048 bytes
EDC, ECC    -  288 bytes
              2352 bytes

mode 2 (audio or video only)

Sector Sync -   12 bytes
Header      -    4 bytes
User Data   - 2336 bytes
              2352 bytes

since the data mode cannot be changed on a track, you can't interleave data
with sound or video.

CDROM-XA

a mode 2 form 1 sector contains

Sector Sync -   12 bytes
Header      -    4 bytes
Sub-Header  -    8 bytes
User Data   - 2048 bytes
EDC, ECC    -  280 bytes
              2352 bytes

and a mode 2 form 2 sector contains

Sector Sync -   12 bytes
Header      -    4 bytes
Sub-Header  -    8 bytes
User Data   - 2324 bytes
EDC, ECC    -    4 bytes
              2352 bytes


With that norm, you can interleave data with sound and video because they
are read in the same mode.

This info comes from a programming manual for a CD-ROM writer. 

Pierre
@EOT:

--- Msgedsq 3.10