ADS Technologies USBAV-708 INSTANT VIDEOMPX, User Manual

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If you intend to use either Slow or Slowest Performance/Quality modes you
can substantially decrease your encoding time by encoding all but the final
pass using
Standard Performance/Quality.
Running either a
Standard pass followed by a Slow pass in place of two Slow
passes or a Standard pass followed by a Slowest pass in place of two
Slowest passes reduces encoding time by approximately 50%, while
impacting so negligibly on quality as to be virtually indistinguishable.
MV re-use can reduce encoding time for
Standard passes. See MV Re-use
for further information.
Disable audio processing on all but the last nth pass to reduce encoding time.
Use Multipass mode to obtain the optimal quality consistency when it is
possible to pass an identical source video through the encoder multiple
times.
When performing more than 2 passes (1st, nth) in order to be effective in
refining the rate control (and hence quality consistency) the option to
Update
log file must be enabled during each nth pass.
Generally 98-99% of the optimal quality is obtained in three passes or less
(1st, nth, nth).
It is possible to use a
1-Pass, Quality-based pass in place of Multipass 1st
pass if you desire to perform the first pass based upon a fixed frame
quantizer. Ensure that Write log file is enabled. The XVID encoder performs
1st pass at Q=2. Using this technique it is also possible to capture a live
source via
1-Pass, Quality-based mode and then recompress it, proceeding
directly to nth pass.
Fastest Performance/Quality mode is unavailable during Multipass encoding
because it does not perform the motion estimation necessary for the rate-
control to work effectively.