7847FSEDA Series
Frame Synchronizer and Distribution Amplifier
Revision 0.1
Page - 39
5.2.10. Downmix
The Downmix audio processing module provides the ability to downmix 5.1 surround sound to 2-
channel (stereo) sound, or single channel (mono) sound. The Downmix audio processor can be
configured to utilize common downmixing algorithms (Lo/Ro, Lt/Rt) and is also fully user configurable.
To embed the Downmix audio processing module output onto the SDI program output, it must be
selected as a source for the embedded audio output mixers (See section 5.2.6 Embedded Audio Mixer)
Figure 5-17 illustrates the layout of these controls in the VistaLINK® PRO configuration view. The
specific functionality of each control is described below.
Figure 5-17: Video Path Configuration - Downmix Tab
Output Scaling Mode:
This control allows the user to determine whether the down mix matrixing is
normalized or not. To normalize matrix coefficients,
Overflow Scaling must be selected.
Normalization of matrix coefficients will avoid any possibility of overflow, but it tends to lower the
loudness level when compared against the original 5.1 input. If no normalization is applied, the stereo
down-mix usually sounds at the similar levels as the 5.1 audio inputs. But clipping may occur when
the input sound level is close to 0dB FS.
Output Gain:
This control allows the user to configure the output gain of the Downmix audio
processing outputs (Downmix L & R). The output gain ranges from -20 dB to +20 dB in 0.1 dB
increments.
LFE Mixing:
This control allows the user to control whether the LFE channel is included or not in the
audio down-mixing.
