Dolby Laboratories S01/13621 - Manual (Page 30)

Dolby Installation Guidelines Installation Issues
3-2
3.2.2 Dolby Digital
The amount of delay added by the Dolby Digital encode/decode process varies
depending upon the sample rate being used. The table below shows the minimum
delay values for encoding. The DP569 allows for the encoding delay to be increased
to any value between the minimum value and 450 ms. The decode latency values are
fixed, dependent on the bitstream detect mode of the DP562. The encoding delays are
correct for v1.22 of the DP569 software. These are likely to change in later versions.
Table 3-1 Dolby Digital Coding and Decoding Delays
Sample
Rate
DP569 Minimum
Coding Delay
DP562 Latency in
Disabled/Reference Detect
DP562 Latency in
Silent Switch Mode
48 kHz 179 ms 32 ms 36.6 ms
44.1 kHz 195 ms 35.7 ms 42.8 ms
32 kHz 268 ms 48.4 ms 58.3 ms
3.2.3 Dolby E
The Dolby E encoding and decoding processes each add one frame of delay to the
audio. The frame length is that of the incoming video reference signal. If the DP572
is in Program Play mode, then the decoding delay will vary depending on the rate of
the incoming Dolby E bitstream.
The Dolby E units also have a PCM delay output. This can be used to route the PCM
input to the PCM output adding the same delay as is being added by the Dolby E
encode process. This can be used to keep a pair of un-encoded audio channels, such
as channels three and four from a VTR, in sync with the encoded audio.
3.3 Setup and Calibration
To allow correct monitoring of the encoded audio, the DP562 includes adjustments
for settings such as analog output level trims and surround delays. For details of how
these should be set, refer to the user manual.
The DP563 requires calibration with the studio’s operating level. For details of how
to perform this calibration, refer to the user manual.
The DP570 has different setup options depending on whether the Cat. No. 548
Analog Option Card is fitted. With the analog board fitted the setup options are
similar to the DP562. However the DP570 allows for multiple sets of speakers for
which level trims can be assigned separately. The DP570 also includes EX decoding
and can therefore support up to 7.1 speaker setups. For full details of setting up these
speakers please refer to the user manual.