Adjustable ATIP?

vbimport

#1

Here you can read about the layout of a cd-recordable. I don't understand what is said there, especially the following sentence:

Since various linear velocities are used other recording areas must have adjustable ATIP times to satisfy this criteria

Can anybody elaborate on this subject? Maybe point me to some websites which explain this? Has anybody already found the colored books on the internet???

:confused:


#2

What it means is that the only recording area (physical position on the disc) with a known time code (00:00.00) is the transition from the lead-in to the program area which is located at 25mm from the center.
The time codes in all the other recording area’s depend on the scanning velocity.
That makes sense of course. With 74min CD-R’s 70:00.00 is located somewhere near the end of the disc while the same time code is located closer to the center of the disc with 99min CD-R’s.
Higher capacity discs have a lower scanning velocity.


#3

I understood that the absolute timecodes of ATIP is hardcoded in the wobble of the pregroove… if it is hardcoded, how can it be adjustable…

:confused:


#4

Yes, but I think they just mean that the timecodes other than 00:00.00 are located on different positions for each CD-R type/brand.


#5

as i understand it…the only defined time on the disc is 00:00:00. after that must come the program. however, why various linear velocities would have an effect on what time a section is is beyond me. maybe differences in nanometers or something, i duno. unless ATIP time is different than Greenwich time…


#6

> Since various linear velocities are used other
> recording areas must have adjustable ATIP
> times to satisfy this criteria

That’s nonsense, forget it.


#7

Ok, so Chip Chapin has got it wrong? Does the term ‘adjustable ATIP’ at least makes some sense or is all the information completely bullocks?


#8

Well, without any more detail than what is on
his page, “adjustable atips” doesn’t make sense
to me, especially in the same sentence as
‘velocity’.


#9

Upp3rd0G’s question is quite interesting:

Has anybody already found the colored books on the internet???

Do the colored books really exist in book-form and if yes: Are they still available?


#10

i thought you had to pay philips a license fee just to be able to see them


#11

The colored books are apparently also available in .pdf format but they are watermarked… (which shouldn’t be a problem… ask Dimitri Skylarov from Elcomsoft! :p)

If you want to buy the colored books from Philips, you have to sign a non-disclosure agreement and pay like 100 euro per book, I want the red/yellow/orange/blue book, but I don’t want to spent 400 euro’s…

I think these are the reasons why they are not available, I have searched everywhere but could not find them…

:frowning:


#12

Originally posted by spath
Well, without any more detail than what is on
his page, “adjustable atips” doesn’t make sense
to me, especially in the same sentence as
‘velocity’.

I think that ‘adjustable atips’ is just a bad choice of words.

What he is trying to say is that regardless of the scanning velocity, the ATIP time 00:00.00 is always located on the same physical position (recording area) on the disc.
The physical location of all other ATIP times depend on the scanning velocity.
A higher scanning velocity means that high ATIP times are located closer towards the physical end of the disc.


#13

> The physical location of all other ATIP times depend on the scanning
> velocity.

Err, by definition a “physical location” does not depend on anything.
ATIP frames simply are where they have been put on the disc, whatever
rotation speed you use will not change that.

> A higher scanning velocity means that high ATIP times are
> located closer towards the physical end of the disc.

Oh, so ATIP frames are sensitive to centrifugal force ? :slight_smile:


#14

By the way, centrifugal force doesn’t exist! :bigsmile:


#15

Originally posted by spath
[B]> The physical location of all other ATIP times depend on the scanning
> velocity.

Err, by definition a “physical location” does not depend on anything.
ATIP frames simply are where they have been put on the disc, whatever
rotation speed you use will not change that.

> A higher scanning velocity means that high ATIP times are
> located closer towards the physical end of the disc.

Oh, so ATIP frames are sensitive to centrifugal force ? :slight_smile: [/B]

The rotation speed has got nothing to do with this.
The scanning velocity which is mentioned in the redbook is the scanning velocity at 1X.
This is a constant parameter of each disc.

OK let’s try an example :slight_smile:

Disc A has a scanning velocity of 1.1 m/s, typical for a 90min CD-R.
ATIP time 00:00.00 is located at 25mm from the center of the disc.
ATIP time 45:00.00 is located at 50mm from the center of the disc.

Disc B has a scanning velocity of 1.3 m/s, typical for a 74min CD-R.
ATIP time 00:00.00 is located at 25mm from the center of the disc.
ATIP time 45:00.00 is located at 55mm from the center of the disc.

The numbers are only a guess, but you should get the picture now.


#16

still not making sense :wink:

74 minute disc, do some math, and you can find approximately where 45 minutes is located. regardless of anything else. same with a 90 minute. at least, i’m assuming so. im way to lazy to do the math, diff eq is enough for the summer :frowning:


#17

Ahhh, so what you call “scanning velocity” is the
nominal CLV speed of a disc, which indeed
decreases as the disc’s size increases (btw
does you red book version really contains
“scanning velocity”, because mine doesn’t).
But then you’re comparing ATIP times of different
discs, while Chip Chapin talks about “other
recording areas”… gee what a weird sentence :frowning:


#18

My thanks to Marco for calling my attention to this thread today (june 19). In fact a few days ago I received a note from someone else at CD Freaks questioning that same statement on my CDMedia site (http://www.chipchapin.com/CDMedia/cdr4.php3).

I had sent the following response, which may be of general interest. I’ve added a few edits for clarity.

Thank you for writing, I appreciate your comments. As I’m sure you noticed, this was a direct quote [from a Richard Whitworth article in Tape Disc Business] in one of the areas where I hadn’t done any analysis of my own.

[But] my interpretation of the offending sentence is as follows:

Given that

  1. Nominal 1x linear velocity (i.e. the linear velocity at which the wobble is at 22.05kHz) can vary between discs, and
  2. The start and ending points of certain disc regions are physically fixed in terms of diameter

Therefore the “ATIP time” [i.e. the nominal duration as defined by the wobble] of those fixed regions cannot itself be fixed.

This seems plausible to me, but I claim no personal expertise in the area. Any elucidation on your part will be more than welcome.

I never received a reply, but having now read this thread, this still seems quite reasonable to me.

By the way I’m looking forward to browsing this site some more. I think this is the first time I’ve been here and it seems like a great resource.

Also, by all means send me any corrections or clarifications regarding material on my CD Media pages. I’m planning to do an update sometime this summer.

Chip Chapin


#19

Note: in my explanation, I am simply saying the same thing as cdrfreak2. I think he or she has it exactly right.

chip


#20

@Chip Chapin

Welcome to this forum. Thanx for your reaction!

:smiley: