New codecs are usually tested annually to check if any offer any conclusive enhancement in quality or compression time. In general, quality is not sacrificed for speed, and the standards will usually opt for the highest quality possible, even if this takes much longer. For example, releases using the Xvid encoder must use the two-pass encoding method, which takes twice as long as a single pass, but achieves much higher quality; similarly, DVD-R releases that must be re-encoded often use 6 or 8 passes to get the best quality.