Tips On Videodiscs - Sony LDP-1500P Service Manual

1-2. TIPS ON VIDEODISCS
TYPES OF VIDEODISCS
CAV (constant angular velocity) disc
The CAV disc always rotates at a constant speed of 1500 r.p.m. and the
laser beam moves from the inner part of the disc to the outer. Up to 36
minutes of playback (54,000 frames) is possible on one side of the disc.
Each frame of the playback picture is recorded on one track and is
reproduced in one rotation. The frame number is recorded on the track.
Flexible playback operation such as variable speed playback, repeat play
or computer-controlled playback is possible using the frame numbers as
reference.
CLV (constant linear velocity) disc
With the CLV disc, the rotational speed varies from 570 r.p.m. to 1500
r.p.m. so that a constant linear velocity is maintained. The laser beam
moves from the inner part of the disc to the outer as with CAV discs.
Playback of up to one hour is possible on one side of the disc, although
only normal play, scan and search operations are possible. The elapsed
playback time or the chapter number being played can be displayed on
the monitor screen. Searches to the beginning of chapters or specified
time codes is possible.
*1) Frames
The CAV discs have up to 54,000 "frames" which are numbered in sequence. One frame is
recorded on one track, that is, a frame is played back with one rotation of the disc.
You can search for a particular frame quickly or repeat a particular sequence of frames.
*2) Picture stop
When the player detects this code, the playback enters the still mode. This code may be ig-
nored in the scan and search modes.
*3) Chapters
There are CAV and CLV discs on which "chapters," as the chapter of a book, are pre-recorded.
If a chapter number is displayed after a frame number has been displayed (on a CAV disc)
or after playback time is displayed in minutes (on a CLV disc) when you change the display
mode, the data are pre-recorded in chapters.
You can easily search for a particular chapter and play it back repeatedly.
*
4) Lead-in/Lead-out
When the player detects the lead-out code, it returns to the beginning of a disc, detects the
lead-in code and repeats playback or stops at the beginning of the program area according
to the AUTO REPEAT switch setting.
When the player detects the lead-in code or lead-out code in SCAN mode, the same result
will be obtained.
1-2