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This article is from the DVD Formats FAQ, by jtfrog@usa.net (Jim Taylor) with numerous contributions by others.

1.35 Why are the audio and video out of sync?

There have been numerous reports of "lip sync" problems, where the audio
lags slightly behind the video, and even reports of the audio coming before
the video. Perception of a sync problem is highly subjective--some people
are bothered by it while others can't discern it at all. Problems have been
reported on a variety of players (notably the Pioneer 414 and 717 models,
possibly all Pioneer models, some Sony models including the 500 series, new
Toshiba models including the 3109, and some PC decoder cards). Certain
discs are also more problematic (notably Lock, Stock, and Two Smoking
Barrels; Lost In Space; TRON; The Parent Trap; and Austin Powers).

The cause of the sync problem is a complex interaction of as many as four
factors

1. Improper sync in audio/video encoding or DVD-Video formatting.
2. Poor sync during film production or editing (especially post-dubbing
or looping).
3. Loose sync tolerances in the player.
4. Delay in the external decoder/receiver.

Factor 1 or 2 usually must be present in order for factor 3 or 4 to become
apparent. Some discs with severe sync problems have been reissued after
being re-encoded to fix the problem. In some cases, the sync problem in
players can be fixed by pausing or stopping playback and then restarting,
or by turning the player off, waiting a few seconds, then turning it back
on. Pioneer has stated that altering the audio-visual synchronization of
their players "to compensate for the software quality would dramatically
compromise the picture performance."

Unfortunately, there is no simple answer and no simple fix. More complaints
from customers will motivate manufacturers to take the problem more
seriously and hopefully correct it in future players or with firmware
upgrades.

 

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