MRD 5800 – User Manual
Page 109 (116)
Appendix E – MRD 5800 Audio Explanation
Downmix Audio Setup
There are two primary modes of audio down mix operation for the MRD 5800
receiver/decoders. These settings only affect the signal if the digital output is set to
PCM. It will also affect those embedded audio channels that are set to a PCM down
mix. There are no gain changes or decoding if the digital or embedded outputs are set
to Pass-through. The preset modes are Monitor (the default setting) and Transmission.
The first preset, Transmission, allows no changes by the customer. Transmission is
intended to provide a limited dynamic range signal to drive a set top box or a transmitter.
The Transmission mode does respond to dialog normalization data. It provides a gain
boost of 11 dB and has compression to prevent the signal from overdriving a modulator.
The 11dB gain boost is applied to the analog outputs, AES digital outputs set to PCM,
and any embedded outputs set to PCM. It will not affect the gain of digital outputs or
embedded outputs set to Pass-Through. It is intended to provide a similar audio level as
a broadcast TV station signal through an RF modulator. The down mix includes the
center and surrounds channels if they are present, and is represented as Lt/Rt. (left total,
right total)
The second preset is Monitor. It has moderate processing, no gain boost and its down
mix involves left and right channels only (Lo/Ro). The mode setting is Line as the default,
but may be changed to RF, Custom 0 or Custom 1. In Line mode, the Dolby Dialog
Normalization data is followed along with moderate processing. The default down mix
setting for Monitor is Lo/Ro. The down mix may be changed to Lt/Rt or Lt/Rt/auto. Lt/Rt
auto follows the embedded data in the stream if the producer has a preferred down mix.
It will switch automatically between Lo/Ro and Lt/Rt depending on the data in the
stream. If no mode is specified, the down mix will be Lt/Rt. In addition, the Dual Mono
modes of operation may be selected. They will only have an effect if the stream is
encoded as Dual Mono. Dual Left or Dual Right applies that signal to both left and right
channels of the digital service, left and right channels of the analog outputs, and left and
right channels of any embedded stream set to PCM. Selecting RF as the compression
setting will add 11 dB of gain and the same processing as the Transmission mode to the
analog outputs, AES digital outputs set to PCM, and any embedded outputs set to PCM.
There is an additional selection at the bottom of the Dolby setup pull-down menu. This
allows selection between Professional Mode and Consumer Mode. In Professional
Mode the built-in latency value is 32 msec for all formats. In Consumer Mode, this
latency varies depending on the format. If you wish to monitor using a consumer
receiver, you should choose Consumer Mode. The output sampling rate will always be
48 kHz, even in consumer. The Consumer/Pro identification bit will be set to Consumer.
Normal operation in the air chain will use the Professional setting. This setting affects
both Dolby Digital (AC-3) and Dolby Digital Plus.
If you want to run with no processing, choose Custom 1, Lo/Ro, and Dynamic Range
disabled. This will still allow gain changes called for in the Dolby metadata via Dial-
Norm settings in the stream.
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