A computer that's equipped with a dual-layer compatible DVD writable drive can burn content to double density, or dual-layer, DVDs. Dual-layer compatible writable DVD drives are common following their introduction in 2004. However, dual-layer writable discs have not gained as wide of traction as the single-layer counterparts because dual-layer discs cost more than double what the single-layer discs cost. Double density DVDs do not pack the physical bits on the disc closer together -- instead the capacity is increased by a second writable layer above the first.

Using the Correct Drive

The only way to write to a dual-layer DVD is to use a dual-layer compatible DVD writable drive. A single-layer DVD drive cannot write data to the second layer of a writable dual-layer DVD. However, dual-layer compatible DVD drives can work with single-layer discs. The drive itself will usually designate whether it supports dual-layer discs by featuring the text "DVR+R DL," "DVD-R DL" or "DVD+-R" on the front of the drive. Additionally, standard DVD drives that can only read discs are not capable of burning dual-layer DVDs.

Using the Correct Media

A dual-layer DVD writable drive needs to have a dual-layer writable disc to burn multi-layer content; a dual-layer drive can't write to two layers on a single-layer disc. Dual-layer discs can hold up to 8.5GB of data whereas single-layer discs are limited to 4.7GB. There are two major competing types of dual-layer writable DVD discs: DVD Dash and DVD Plus designated as "DVD-R" and "DVD+R." Some writable DVD drives, designated as "DVD+-R" are compatible with both "DVD-R" and "DVD+R" discs. However, if the drive is not compatible with both it can only work with one type. A "DVD-R" drive can only burn to dual-layer "DVD-R" discs and a "DVD+R" drive can only burn to dual-layer "DVD+R" discs.

Double Density Software Configuration

Some DVD authoring programs may place artificial caps on how much data the user can store on the disc. The artificial caps can be a problem when configured to 4.7GB when you're working with dual-layer discs. The process varies within DVD authoring programs and some can automatically detect the disc size. Programs that don't automatically detect the disc size often can be configured to the 8.5GB capacity within a "Settings" or "Preferences" menu. Some programs offer different burning options for single-layer and dual-layer discs at launch or through a drop menu. In the case of Nero, dual-layer compatibility is enabled by selecting the "DVD9" option from the bottom-right screen drop menu.

Playback Device Compatibility

Some DVD playback devices might have compatibility problems with dual-layer writable DVDs. According to Cnet, some DVD players have difficulty reading content on dual-layer DVDs altogether. According to PC Magazine, splitting movie content across two layers on a writable disc can cause the player to have a hard time finding cross-layer content through menus.