Archived - iDVD: Burning Double-Layer DVDs
With iDVD 5.0.1 or later (including iDVD 6.x), you can burn Double-Layer DVDs with the SuperDrives installed in most new computers (Find out if you have a DL capable drive). Double-Layer (DVD+R DL) discs have two layers of data, allowing the SuperDrive laser to read and write on either layer, which almost doubles the storage to 8.5 GB.
Before burning your DVD, be sure that you have at least twice as much free hard disk space available as your project uses to allow for encoding and burning; you can track your DVD project size in the Status pane of the Customize drawer. For example, if your project size is 8 GB, you need at least 16 GB of free space on your hard disk to encode and burn the project to disc.
iDVD '08 (7.x), iDVD 5.x, iDVD 6.x
If you use the Best Performance option in the Encoder Settings section of iDVD Preferences, you can use up to 2 hours of video in your double-layer project. If you select the Best Quality option, you can fit up to 4 hours of video on one Double-Layer DVD. If you wish to burn a single-layer DVD in one of the Double-Layer-supported SuperDrives, select the 4 GB (Single Layer) option in the Project info window in iDVD.
If your computer doesn't have one of the new SuperDrives installed, you'll be limited to single-layer DVD creation. You should only create Double-Layer disc images for testing purposes (it is only an option if you have a new SuperDrive installed). Burning those disc images to a DVD using a utility outside of iDVD will not set the layer break according to the DVD specification and may result in playback issues.
Note: If the amount of data in your project does not require a second layer, iDVD will ask if you wish to use a single-layer recordable DVD instead of recording the project on a Double-Layer disc.
Not all computers or DVD players will be able to read a DVD+R DL disc. See "Not all DVD players support all media types" for more information.