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Reference
46
764 Digital Audio Monitor User Manual
V BIT — Indicates that the Validity bit is set high for one or more data
samples. In the AES/EBU standard, a set validity bit indicates that
the sample is not suitable for conversion to audio. By default, The
meter bars and phase display treat the affected samples as a zero
samples. When Session is running, the instrument counts “invalid
samples” and displays the total on the Session view.
You can suppress the V BIT message by setting the “Ignore Validity
Bit” item in the Level Meters submenu to YES. If you do so, the 764
will treat all samples as valid, and the word “off” will appear in the
Invalid samples fields of the Session view. This feature is included
because the use of the Validity bit varies despite its official meaning
as specified in the AES/EBU standard, and you may find it desirable
to monitor audio from “invalid” samples.
Correlation Meter Algorithm
The correlation meter reading is calculated 60 times each second
from
1
@
60
-second-long blocks of interpolated (“4x oversampled”)
input data. The formula used to drive the correlation meter is:
C + (sign)
ȧ
ȱ
Ȳ
4fsń60
ȍ
n+0
(
L
n
R
n
)
ȧ
ȳ
ȴ
2
ȧ
ȱ
Ȳ
4fsń60
ȍ
n+0
(
L
n
)
2
ȧ
ȳ
ȴ
ȧ
ȱ
Ȳ
4fsń60
ȍ
n+0
(
R
n
)
2
ȧ
ȳ
ȴ
Ǹ
Where
f
s
= the sampling frequency, in Hz (for example, 48000);
L
n
= the value of the nth left-channel sample; and
R
n
= the value of the nth right-channel sample