ZvBox
®
170
Configuration
Manual
Page
11
www.zeevee.com
Rev
1.0
Select
Underscan
Resolutions
to
Present
in
VGA
EDID
When
ZvBox®
170
is
connected
to
a
computer
via
the
VGA
connector,
ZvBox®
presents
to
the
computer’s
graphics
card
a
set
of
resolutions
that
are
supported
by
ZvBox®,
including
the
1280
x
720
resolution
used
by
HDTVs.
These
resolutions
are
presented
in
a
structure
called
EDID
(Extended
Display
Identification
Data).
If
ZvBox®
is
broadcasting
a
full
1280
x
720
resolution
to
an
HDTV
that
“overscans”
(crops
off
the
edges
of
the
picture),
important
information
may
be
lost,
e.g.
a
PC
taskbar
or
a
scrolling
ticker
at
the
bottom
of
the
screen.
In
that
case
it’s
possible
to
choose
a
ZvBox®
‐
supported
“underscan”
resolution
at
the
PC,
generating
a
slightly
smaller
picture
that
will
remain
within
the
viewable
area
of
the
HDTV
screen.
The
following
command
allows
you
to
set
an
underscan
resolution
for
720,
which
will
be
communicated
to
your
PC
via
EDID.
Once
an
underscan
resolution
has
been
selected,
you
may
set
your
PC’s
output
resolution
to
that
resolution.
Note:
each
TV
will
perform
a
different
amount
of
overscan,
so
keep
this
in
mind
when
selecting
an
underscan
resolution.
It
can
be
useful
to
have
the
ZvBox®
output
test
‐
image
‐
1
(i.e.
“set
video
‐
source
test
‐
image
1”)
when
determining
the
correct
underscan
resolution.
Syntax
SET
VGA
‐
RES
{1264x711
|
1248x702
|
1232x693
|
1216x684
|
1200x675
|
1184x666
|
1168x657
|
1152x648
|
1136x639
|
1120x630}
MPEG2
Encoding
Control
This
group
of
commands
can
be
used
to
fine
‐
tune
the
characteristics
of
the
MPEG2
encoder.
The
factory
defaults
have
been
set
to
values
that
produce
the
best
picture,
while
also
maximizing
the
chance
that
all
HDTVs
will
correctly
display
the
encoded
video.
We
have
found
that
some
HDTVs
are
sensitive
to
certain
things
like
total
bit
‐
rate
or
number
of
bits
of
DC
coefficients.
The
picture
may
sometimes
break
up,
or
in
some
cases
not
display
at
all!
Experimenting
with
these
settings
can
improve
the
quality
of
the
encoded
video,
but
we
strongly
advise
you
to
test
any
changes
on
*each
type
of
HDTV*
that
may
receive
the
signal.
Set
Encoding
Bit
Rate
A
digital
cable
(QAM)
RF
channel
allows
for
a
data
rate
up
to
38.78
Mbps.
Usually,
that
stream
is
divided
into
multiple
digital
channels,
each
having
a
lower
effective
data
rate.
Since
ZvBox®
is
placing
a
single
digital
channel
in
the
stream,
it
can
send
more
data
during
complex
scenes,
up
to
the
38.78
Mbps
limit.
This
can
result
in
significant
improvements
in
video
quality
for
certain
very
complex
scenes.
However,
some
HDTVs
will
experience
some
picture
breakup
if
the
data
rate
ever
exceeds
19.4
Mbps
for
a
single
digital
channel.
We
have
observed
that
this
is
true
of
some
Sharp
HDTVs,
and
may
be
true
of
others.
“Normal”
will
keep
the
encoder’s
output
data
rate
to
19.4
Mbps.
High
will
allow
the
encoder
to
operate
up
to
38.78
Mbps.
At
this
time,
Low
and
Normal
have
the
same
effect.
Syntax
SET
DATA
‐
RATE
{low
|normal
|
high
}
factory
default
:
high
