Why do i always get out of sync dvds?

[mrjust]

i just encoded and .avi to dvd and the audio is out of sync!
i always encode audio and video separately.

Does the audio and video have to be the exact same time!

EXAMPLE: video 1:20:50:58
and audio 1:20:50:58

or is it ok if the audio is a different time? im asking because the audio is always off by ms(milliseconds).

[jagabo]

The audio on DVDs is often shifted relative to the video. For example, it may start a second later. In cases like that you can adjust the audio by adding a second of blank audio to the start, or using the audio skew ability of AVI files.

DVDs can also use variable frame rates. For example it may shift from 23.976 fps with pulldown flags to 29.97 fps interlaced. This can confuse some conversion programs.