How
passthru
audio
function
-
Dolby
E
/
5.1
/
2.0,
Dolby
D,
LPCM
The
Adtec
EN-31
encoder
supports
four
pairs
of
audio
encoding
or
two
pairs
of
passthru
per
service.
An
audio
passthru
consists
of
a
compressed
bitstream
(
Dolby
E
20
Bit
/
Dolby
E
16
Bit
/
Dolby
Digital
/
Linear
Acoustic
Stream
Stacker
2
)
or
an
uncompressed
stereo
pair
(
LPCM
)
from
embedded
SDI
passed
into
the
egress
transport
stream
(
IP,
*RF,
ASI
).
To
enable
Audio
passthru
for
Audio
1:
Step Action
1
On
the
Audio
->
Encoder
1
subtab
in
the
Web
GUI
Control
Application,
configure
the
"Audio
Mode"
for
<PASSTHRU>.
2
Configure
the
“Audio
Input”
for
<SDI>
.
3
Select
the
type
of
audio
from
the
“Type”
drop
down.
<
Dolby
Digital
>,
<
Dolby
E
>,
or
<
Linear
PCM
/
E2
>.
note:
If
Dolby
E
or
Dolby
Digital
is
valid
at
the
input,
the
bit
depth
and
bitrate
are
automatically
determined
after
clicking
Apply.
4
On
the
“PID”
tab,
type
in
the
desired
Audio
PID
for
“Audio
1”
.
Common
Passthru
Problems:
Dolby
E
Line
Placement
and/or
Dolby
E
Continuity
Count
Errors:
Dolby
E
audio
compression
technology
is
designed
so
that
1
Dolby
E
audio
frame
corresponds
to
1
Video
frame.
This
1:1
ratio
of
video
and
audio
timing
was
designed
to
assist
in
Video
editing
and
seamless
cuts
without
losing
audio
data.
Due
to
the
crucial
and
sensitive
timing,
Dolby
E
encoders
must
have
a
reference
phase
locked
to
the
video.
In
other
words,
the
SDI
video
timing
feeding
the
encoder
must
match
the
same
composite
reference
timing
that
is
connected
to
the
Dolby
E
encoder.
A
simple
black
burst
generator
that
does
not
share
the
same
SDI
video
timing
will
not
work
to
source
a
Dolby
E
encoder.
A
composite
video
reference
that
shares
the
same
timing
as
the
video
source
should
be
used.
The
encoder
preserves
audio
and
video
timing
as
it
is
presented.
If
the
audio
timing
does
not
match
video
timing
at
the
inputs
of
the
encoder,
there
will
be
line
placement
errors
and/or
CRC
errors
seen
on
a
decoder.
If
Detection
of
Dolby
E
/
Dolby
Digital
is
not
present,
the
Front
Panel
Quickview
will
show
“DE
---”
or
“DP
---”
and
the
corresponding
Front
Panel
LEDs
will
blink.
The
encoder
will
automatically
detect
the
bit
depth
of
Dolby
E
(
16
/
20
bit
)
and
the
bitrate
of
Dolby
E
/
Dolby
Digital.
If
Dolby
E
is
selected
and
Dolby
Digital
is
presented,
the
encoder
will
change
automatically
and
vice
versa.
If
Dolby
Digital
is
selected
and
Dolby
E
is
presented,
the
encoder
will
change
the
configuration
automatically.
If
the
front
panel
shows
dashes
for
the
detected
bitrate
‘---’,
Dolby
is
not
being
detected.
This
is
most
commonly
due
to
a
mis-configured
SDI
Audio
Matrix
or
Dolby
not
being
present
on
the
specified
input
pair.
Look
at
the
SDI
signal
on
an
SDI
analyzer
to
verify
that
Dolby
is
present
on
the
pair
intended.
If
an
SDI
analyzer
is
not
available,
one
troubleshooting
tip
is
to
set
the
mode
to
ENCODE.
If
silence
or
regular
audio
is
heard
on
the
decoder,
a
compressed
bitstream
is
43
