Opposite Track Path

This article may need to be wikified to meet Wikipedia's quality standards. Please help by adding relevant internal links, or by improving the article's layout. (September 2010) Click [show] on right for more details. No reason has been cited for the Wikify tag on this article. Please replace HTML markup with wiki markup where appropriate. Add wikilinks. Where appropriate, make links to other articles by putting "[[" and "]]" on either side of relevant words (see WP:LINK for more information) and check that your links work as expected. Please do not link terms that most readers are familiar with, such as common occupations, well-known geographical terms, and everyday items. Format the lead. Create or improve the lead paragraph. Arrange section headers as described at Wikipedia:Guide to layout. Add an infobox if it is appropriate for the article. Remove this tag.

Opposite Track Path (OTP) is a term used in optical technology, allowing fast switching from layer 0 to layer 1.

A dual-layer DVD or Blu-ray disc with Opposite Track Path means that layer 0 is written in a spiral track starting at the inside of the disc, whereas the layer 1 spiral starts at the outside of the disc. Both tracks are written so that the DVD player will rotate the disc in the same direction. When reading the disc sequentially (as is done during DVD video playback), OTP enables the player to switch from layer 0 to layer 1 without a seek across the entire disc.

With the DVD technology, a small gap is left in the layer 1 track every time it crosses the layer 0 track (twice per revolution). As a result, the data capacity of layer 1 is less than layer 0 which means that a dual layer disc only has a capacity of 8.5 GB instead of the 9.4 GB that might have been expected.

In the case of Blu-ray discs, it was realised that the gap was unnecessary as the laser is perfectly capable of focussing through track 0. Consequently, dual layer Blue-ray discs have double the capacity of their single layer counterparts(50 GB as against 25 GB).

References

• Opposite Track Path, DVD Burning Glossary.

This computer storage-related article is a stub. You can help Wikipedia by expanding it. v d e