May 9th 05, 10:20 AM
Various Forums have suggested that when recording your own DVDs and CDs
that "Skipping" and "Stalling" can occur if "Stick-On Labels" are used.
Various people have commented that by removing the label from a
skipping disk the disk then plays normally again. Therefore I'd like
make a few "Technical" suggestions as to why the label could be causing
this problem.
There are at least 2 theories:
1/ Wobble
The label may be placed slightly off-center thus causing the disk to
wobble more. The laser scanning the disk has the ability to focus the
laser beam on the disk. However the wobble is at a greater rate than
the mechanism can track - hence data corruption.
Observation:
Disks with labels seem to perform better with less problems when used
in "PC DVD and CD Drives".
My theory would be that PC DVD and CD Drives rotate "Faster" than DVD
and CD players. PCs can copy disks at many times the normal play rate.
This is indicated on the drive by statements like " X40 " meaning it
can read the disk 40 times faster than normal play. Thus in this
example a 40 minute CD would read in 1 minute.
This higher "Rotation Speed" makes the "Centrifugal Force" on the disk
greater thus keeping the disk more "Rigid" and wobble less.
I've found that DVDs tend to skip more towards the "Middle" and "End"
of the video - not so much at the beginning.
DVDs and CDs are recorded from the "Inside" - outwards. Therefore the
wobble would be more pronounced on the outside of the disk as it is
further away from the support of the disk's "Clamping Mechanism".
Other observers have suggested that the wobble makes the "Drive
Bearings" hotter thus linking it with Theory Number 2" below...
2/ Temperature
The disk label prevents the top of the disk from "Radiating Heat".
The laser hitting the disk causes local heating. The disk rotation
causes "Eddy Currents" to form which take away the heat from both
sides.
This is called "Scrubbing" and is the same effect that keeps hard disk
drives cool and clean. Dust particles are also scrubbed away and attach
themselves to a "Scrubbing Filter" within the sealed enclosure.
However with one side of the DVD insulated by a paper label there will
be a "Temperature Difference" between one side and the other. This
causes the disk to warm up.
The data is stored in a very thin "Aluminum" layer and being metal
expands. This expansion may then be the cause of data corruption and
skipping.
Observation:
Cold DVDs work more reliably but if played or exposed to higher
temperatures like in a car for example, will skip more if they have
labels on.
Comments and more suggestions related to these theories please.
Harvey Twyman
CV: http://www.twyman.org.uk/CV
that "Skipping" and "Stalling" can occur if "Stick-On Labels" are used.
Various people have commented that by removing the label from a
skipping disk the disk then plays normally again. Therefore I'd like
make a few "Technical" suggestions as to why the label could be causing
this problem.
There are at least 2 theories:
1/ Wobble
The label may be placed slightly off-center thus causing the disk to
wobble more. The laser scanning the disk has the ability to focus the
laser beam on the disk. However the wobble is at a greater rate than
the mechanism can track - hence data corruption.
Observation:
Disks with labels seem to perform better with less problems when used
in "PC DVD and CD Drives".
My theory would be that PC DVD and CD Drives rotate "Faster" than DVD
and CD players. PCs can copy disks at many times the normal play rate.
This is indicated on the drive by statements like " X40 " meaning it
can read the disk 40 times faster than normal play. Thus in this
example a 40 minute CD would read in 1 minute.
This higher "Rotation Speed" makes the "Centrifugal Force" on the disk
greater thus keeping the disk more "Rigid" and wobble less.
I've found that DVDs tend to skip more towards the "Middle" and "End"
of the video - not so much at the beginning.
DVDs and CDs are recorded from the "Inside" - outwards. Therefore the
wobble would be more pronounced on the outside of the disk as it is
further away from the support of the disk's "Clamping Mechanism".
Other observers have suggested that the wobble makes the "Drive
Bearings" hotter thus linking it with Theory Number 2" below...
2/ Temperature
The disk label prevents the top of the disk from "Radiating Heat".
The laser hitting the disk causes local heating. The disk rotation
causes "Eddy Currents" to form which take away the heat from both
sides.
This is called "Scrubbing" and is the same effect that keeps hard disk
drives cool and clean. Dust particles are also scrubbed away and attach
themselves to a "Scrubbing Filter" within the sealed enclosure.
However with one side of the DVD insulated by a paper label there will
be a "Temperature Difference" between one side and the other. This
causes the disk to warm up.
The data is stored in a very thin "Aluminum" layer and being metal
expands. This expansion may then be the cause of data corruption and
skipping.
Observation:
Cold DVDs work more reliably but if played or exposed to higher
temperatures like in a car for example, will skip more if they have
labels on.
Comments and more suggestions related to these theories please.
Harvey Twyman
CV: http://www.twyman.org.uk/CV