DVD Burners

[sinsi]

Thanks for your responses! The strange thing is this only seems to occur with DVD-R discs. When I use DVD-RW discs I can play them in all my DVD players. Are DVD-RW discs more forgiving of write discrepancies between burners? I'm thinking about just getting an external DVD burner for my laptop , this might be an easy solution to the problem. 

There are DVD+ and DVD- discs, generally the plus discs are better due to lower tolerances but also easy to coaster if a write fails.

It means that if you tell 2 drives "track 56" ... both heads do not move to the same place on the disc. 

Track 56 is a logical thing, there is only 1 track on a disc. Drives look at the extra data in a physical sector to find out where it is.

[CommonTater]

It means that if you tell 2 drives "track 56" ... both heads do not move to the same place on the disc.

So you're assuming that the "track" positioning mechanism operates open loop?

It has to do exactly that when writing to a blank disk...

[MichaelW]

It has to do exactly that when writing to a blank disk...

Are you sure of this or are you guessing?

As I demonstrated, temperature variations can easily cause the disk dimensions to vary by many track pitches. If it worked the way you seem to think, the disks would not work reliably even in the same drive.

[jj2007]

It has to do exactly that when writing to a blank disk...

Are you sure of this or are you guessing?

As I demonstrated, temperature variations can easily cause the disk dimensions to vary by many track pitches. If it worked the way you seem to think, the disks would not work reliably even in the same drive.

The two options do not exclude each other:
- when writing to a virgin disk, the head will start with a "neutral" position and advance stubbornly until the spiral ends.
- when reading, the head adapts to what it finds (reads extra data until track 56 is reached etc...).

[MichaelW]

I think the virgin disk must have some sort of tracking data and/or lead in signals built in. The original design specified a recording area from 46 to 117mm, a signal area from 50 to 116mm, and lead-in and lead-out signals used to "control the movement of the optical pickup". And it provided for "control bits" inserted after the sync bits, equivalent to ~2.7% of the total digital codes recorded on the disk, that "let you locate any portion of music exactly and quickly". And there were also provisions for a table of contents, control codes, music start flags, track numbering and indexing, and time codes.

[dedndave]

never got into optical recording, much
but, it would seem more logical to write the tracking signal when you write the data