You may get an audio encoding error message when you try to burn a DVD in iDVD 5 that contains an iMovie HD project without any audio (such as an iMovie project that contains only still images). The burn process will stop and you'll see one of the following alerts:
"Encoding Audio. Error during rendering/encoding: Audio_<project name> -1"
or
"Error during rendering/encoding"
To resolve this issue, open your iMovie project in iMovie and add a short audio track anywhere in the timeline. You can even create a blank audio track by recording from an audio input source that doesn't have any active audio (such as recording from your computer's audio Line In without connecting a microphone). The audio track doesn't have to be long or have audible content—it just needs to be part of the project.
Once you save the iMovie project, you can go back to iDVD to burn it.
Tip: If the burn fails in this manner, it's likely your DVD media remains untouched and can be reused.