Chapter 20 • Video Quality; Preview Image Quality; Video Scaling Artifacts; Slide/Compress Motion Effects - Videonics MX-1 Instruction Manual

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Chapter 20 • Chapter 20 •
The Digital Video Mixer is
designed to meet the highest video
standards. A number of video ar-
tifacts can be created, especially
when fancy video effects are in
use. This chapter describes com-
mon artifacts.
Note: This chapter discusses ad-
vanced video concepts.

Preview Image Quality

The preview images in the PRE-
VIEW screen are designed to moni-
tor the action and don't match the
Mixer's normal quality. They also do
not show input effects or the results
of the advanced setup options. De-
pending on what type of sources are
connected, there may be occasional
lines appearing alongside the preview
images. This is especially likely when
you use cue or review (search) with a
VCR or camcorder connected to an
input.
However, note that:
• The quality of the preview images
has no effect on the video output
quality.
• You can switch to a full-size, full
frame-rate version of the NEXT or
CURRENT source at any time by
pressing the DISPLAY button. (The
DISPLAY button causes the PRE-
VIEW monitor to alternate be-
tween the normal PREVIEW
screen, the NEXT source, and the
CURRENT source.)
VIDEONICS DIGITAL VIDEO MIXER
Video Quality

Video Scaling Artifacts

When a video image is reduced in
size, some picture information must
be discarded because the picture is
displayed using a smaller number of
pixels (picture dots) than normal. One
aspect of this is that small details may
be missing as pixels are removed.
Lines may become slightly jagged as
the picture is reduced and portions
of the line are removed to accom-
plish the reduction in size. When a
picture is being scaled down gradu-
ally, as in some transition effects,
small features may appear and dis-
appear as the pixels that contain them
are successively included or ex-
cluded.
All these effects are normal when
performing advanced effects and are
quite minor, especially when the tran-
sition is performed at normal speeds.
Slide/Compress Motion
Effects
Depending on the relative timings
of the input signals, a thin black stripe
may separate the two images when
you use an effect that includes a com-
press or slide. Its width may vary as
you perform the effect manually.

Freeze Quality

The Mixer's freeze function is a
"field freeze." It captures one field
(half a video frame) and duplicates it
to make the two fields that comprise
a frame. The advantage of a field
freeze is that it eliminates flashing