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Automatic Delay
Compensation /
Time Alignment
C H A P T E R
4 :
G E T T I N G
F R A M E W O R K
Figure 4.31: Signal Preprocessing Options
In the group box
Coarse delay compensation
average delay between the reference and the test signal is determined and
applied to the signals. By selecting "Automatic delay compensation", this will
be done automatically. In this case the radio buttons "Left" and "Right"
determine on which channel of a stereo input signal the delay detection is
performed. Nevertheless the delay found will be used for compensation on
both channels. The delay range that can be compensated for in this mode is
depending on the measurement algorithm used.
The maximum delay that can be compensated for automatically is
PSQM and PEAQ offline measurements. For PEAQ online measurements it is
±
500 ms. PESQ uses a different time alignment algorithm and can compensate
±
for to approximately
Technical Specifications Section.
When performing
online measurements
automatic delay compensation, the Normal Mode and the Snap Mode. In the
Normal Mode, the delay between the reference and the test signal is
permanently checked. When the delay has changed, the new delay is
calculated which can take a duration of several frames. During this time, the
signal data is not evaluated by the measurement algorithm.
In the Snap Mode, the delay is determined and compensated only once. This
delay is maintained for the rest of the measurement or until Snap Again (see
T O
K N O W
20000 ms. For further information, please refer to the
, two modes are available for the
64
T H E
O P E R A ™
choose the way in which the
±
1000 ms for
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