🚀 go-pugleaf

In article <2688@radio.oakhill.UUCP> charlie@oakhill.UUCP (Charlie Thompson) writes:
>Can anybody tell me what the following CD subcode bits
>are defined as?  They are: P Q R S T U V W as shown...

>-Charlie Thompson

A CD player collects 98 consecutive frames to form a sub-code block, with
eight 98-bit words.  Thus the eight subcode bits (P through W).  Only
the P and Q bits are required in the audio CD format.  The P channel
contains a flag bit designating the start of a track, as well as the lead-
in and lead-out areas on a disk.  A lead-in signal consists of all 0s
appearing just prior to the beginning of the music data.  A start flag
appears just prior to the start of music.  During the last music track,
preceeding the lead-out, a start flag appears again.  That flag gives the
start of lead-out and the P channel remains at 0 for 2 to 3 seconds.
Following that time, a P signal of alternating 1s and 0s at a 2-Hz rate
appears.  These various sets of identity signals can be used by a basic
player to control the optical pickup.

The Q channel contains four basic kinds of information: control, address,
"Q data", and cyclic redundancy check code.  The control information
consists of such things as number of audio channels, whether pre-emphasis
should be engaged, digital copy protection, and so forth.  The address
informations consists of 4 bits indicating what kind of information is
contained in the "Q data".  The Q data consists of TOC (table of contents),
track numbers, univeral product codes, international standard recording
codes, and a some other stuff.  Different information is contained in the
Q data depending upon not only the address field, but the location (lead-in,
during music, lead-out, etc).  It's fairly baroque so I'm not going into
detail.

The other six bits (R, S, T, U, V, and W), which account for about 20 Megabytes
of data, are available for video or other information.

See: Journal of the Audio Engineering Society, Vol 36, No. 4, 1988 April.

Have a nice day.