pecet: Re (DLUGIE!!!): CD-R i CD-DA

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The CD-DA was defined in 1982 in the RedBook by Philips and Sony. A
CD-DA sector has 2,352 bytes of user data. The sectors are addressed
by minutes, seconds and sectors. The address information is stored in
the subchannel (Q). The maximum running time of a 12-cm CD is 74
minutes, an 8-cm single CD has a running time of about 21 minutes.
There are two time measurements for addressing a CD audio: by ATime,
which means "Absolute Time", and is measured from the start of the
disc; and by Track Relative Time, which is measured from the start of
a track. 99 tracks on one disc can be accessed directly by a CD-DA
player. A track is a continuous data sequence. Each track must contain
at least 4 seconds (i.e. 300 sectors, since 1 second is divided into
75 sectors). A maximum of the entire CD can be used for one track. A
single tune or musical sequence on CD-DA refers to one track.
On a CD-DA all 2,352 bytes of a sector are user data, thus 2,353 bytes
multiplied by 75 sectors equals 176,400 bytes, which are transferred
per second. This equals about 1.41 Mbit/sec. A cross-check: CD-DA
works on a sampling rate of 44,1 kHz and 16 bit samples for 2 stereo
channels, i.e. 44,100 x 16 x 2=1,411,200 bit/sec or 176,400 bytes of
audio data per second.
For each sector and 2,352 bytes of user data, 882 additional bytes are
stored on the disc for the 2 layers of error detection and correction
code of CIRC (784), and the Control Bytes (98). Each bit of the
control byte is given a letter, "P", "Q", "R", "S", "T", "U", "V", and
"W". The first bit is designated as "P", the second "Q", and so on.
The data stream resulting from all first bits of the 98 control bytes
is called "P" subchannel, the stream of all second bits "Q"
subchannel. The third subchannel combines the bits "R", "S", "T", "U",
"V" and "W" to a 6-bit word, and the data stream of these bits,
resulting from the 98 control bytes, is called "R thru W" subchannel.
The "P" subchannel has a flag that indicates when the audio data in a
track is beginning. "Q" subchannel gives the time code, ATime and
Track Relative Time. In the lead-in of the disc this subchannel
contains the Table of Contents (TOC). 72 of the 98 bits of the
"Q"-subchannel are used for information, the others for
synchronization, control and error correction (for the subchannels).
Beside sync, control and error correction bits, the "R thru W"
subchannel may include user data (64 6-bit words per sector) for
additional information. Only the RedBook allows this (for CD-DA),
while the "YellowBook" specifies that these bits are set to 0. On an
Audio CD, the "R thru W" subchannel is sometimes used for graphic or
MIDI data. (MIDI stands for Musical Instrument Digital Interface and
means a standard protocol for communication between electronic musical
instruments and computers. MIDI files contain messages which refer to
the MIDI specification and which can be interpreted by MIDI devices).
These discs are called CD+G (Compact disc plus graphics) or CD+MIDI,
and can be displayed by a special player in conjunction with a TV and
hi-fi set. 
This subchannel can also be used for user-defined data CD+G titles can
be read by CD-i players and some special Japanese consumer players.
CD+G and CD+MIDI can be interpreted by Tandy's VIS player (VIS stands
for Video Information System) and Commodore's CDTV player. However,
these formats are rare.
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Re (DLUGIE!!!): CD-R i CD-DA - co wiecie? ;)