Cobalt Digital COMPASS 9083 HD_SD Frame Sync - Manual (Page 16)

1
9083 Functional Description
1-12 9083 PRODUCT MANUAL 9083-OM (V4.5)
2.0-to-5.1 Upmix Function
Note: Upmix function is an optional licensable feature. This function and its controls
appear only when a license key is entered and activated. (This option (identi-
fied in Cobalt
® price lists as +UM) can be purchased upon initial order, or
field-activated using a key string which is sent to you when this option is pur-
chased.)
The 2.0-to-5.1 upmixer function receives a normal PCM stereo pair from the
Audio Routing/Gain Control function and upmixes the pair to provide 5.1
channels (Left (
L ), Right ( R ), Center ( C ), Low Frequency Effects ( LFE ), Left
Surround ( Ls ), and Right Surround ( Rs )). Whenever the upmixer is active, it
overwrites the six selected channels with the new 5.1 upmix signals
(including replacing the original source stereo
L and R inputs with new L and
R signals).
The 2.0-to-5.1 upmixer can be set to up mix in any of three modes: Always
upmix, Bypass upmix, or Auto enable/bypass upmixing. The Auto upmixing
mode looks at the signal levels on the selected channels and compares them to
a selectable level threshold. It then determines whether or not to generate 5.1
upmixing from the stereo pair as follows:
• If the upmixer detects signal level below a selected threshold on all
four of the selected channels designated as
C , LFE , Ls , and Rs , this
indicates to the upmixer that these channels are not carrying 5.1. In
this case, the upmixer overwrites all six selected channels with the
new 5.1 content.
• If the upmixer detects signal level above a selected threshold on any
of the four selected channels designated as
C , LFE , Ls , and Rs , this
indicates to the upmixer that the channel(s) are already carrying
viable 5.1 content. In this case, the upmixer is bypassed, allowing the
original channels to pass unaffected.
The examples in Figure 1-6 show the automatic enable/disable up-mixing
function applied to example selected channels
Emb Ch 1 thru Emb Ch 6 . As
shown and described, the processing is contingent upon the signal levels of
the channels selected to carry the new 5.1 upmix relative to the selected
threshold (in this example, -60 dBFS). Note also that this function is applied
after the Audio Routing/Gain Control function. Because all audio inputs pass
through the Audio Routing/Gain Control function before the up mixer, the up
mixer can use embedded, AES discrete, and/or analog audio sources.