ADS Technologies USBAV-708 INSTANT VIDEOMPX, User Manual

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Performance/Quality
The fastest performance/quality mode causes
the encoder to perform no motion search when
encoding. Because no motion estimation is done
all blocks will either be intra-blocks or
predicted with a null motion vector. In
this respect the encoded video will
resemble an MJPEG sequence.
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Fastest
Because fastest mode saves mainly intra-blocks it can consume an
excessive number of bits. Generally this means 1-Pass mode is unsuitable
when working with fastest mode and you should instead use only 1-Pass
quality-based mode, fixing the quantizer much the same as you might set the
compression factor when saving a JPEG image in a paint program.
If you choose to use Fastest mode in combination with 1-Pass mode the
encoder may fail to meet the average bitrate unless a very high average
bitrate is specified.
Fastest mode is unsuitable for use during multipass encoding because the
rate control algorithm used by the multipass system relies on accurate motion
complexity statistics to correctly distribute bandwidth throughout the video.
Therefore, multipass does not support Fastest mode.
Fastest mode is ideal for capture situations where exceptionally high image
quality is required - for example when you intend to later re-compress the
video using another mode.
When Fastest performance/quality mode is selected the encoder does not
respect the following options: Quarter-pixel, Global motion compensation, Bi-
directional encoding, Psychovisual enhancement, MV re-use, Scene change
threshold.
The Maximum Keyframe Interval is limited to 60 frames when Fastest mode
is enabled. Entering any interval larger than 60 frames will cause the encoder
to default the Maximum Keyframe Interval to 10 frames.