Layer type
The layer type is a field of two bits at the start of every DVD (in the physical format information section of the control data block) that indicates what the physical format of the disc is [1]. Similar to book type, this field is set at burn-time by a DVD recorder and can be used by devices to determine how the disc should be treated. However, very few devices use this field with Audi Navigation Plus [2], the Xbox (console) [3], and the Xbox 360 [4] being the only known devices to use it. It is speculated that this value should only be set to "read-only" for factory-pressed discs, but a handful of retail DVD recorders have their firmware set to burn discs as read-only. This could be changed, similarly to book type, on an existing incompatible DVD recorder by using custom firmware, but no custom firmwares currently exist to target layer type.
One example of usage of the layer type feature is for the Audi Navigation Plus (RNS-E) which can only be updated using a disc set to "read-only". This is likely a security feature so that the system can only be updated using a disc from a factory with the assumption that all retail-available DVD recorders would be unable to burn a compatible disc.
These are the possible values of the Layer Type field:
| Value | Meaning |
|---|---|
| 00 | Unused |
| 01 | Read-only |
| 10 | Recordable (writeable) |
| 11 | Re-writeable |
See also[edit]
- Book type, a similar disc bitsetting feature
This article "Layer type" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:Layer type. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.
- ↑ https://docs.microsoft.com/en-us/windows-hardware/drivers/ddi/ntddcdvd/ns-ntddcdvd-_dvd_layer_descriptor
- ↑ https://www.ttforum.co.uk/forum/viewtopic.php?f=19&t=1847605
- ↑ https://old.reddit.com/r/originalxbox/wiki/dvd_demos
- ↑ https://en.wikipedia.org/wiki/Xbox_360_technical_specifications#DVD_storage
