Nevion PGM-HD-2x1-PB - Manual (Page 12)

PGM-HD-2x1-PB Rev. B
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5 Functional description
The goal of this chapter is to give an overview of the data path for audio and video,
show which processing options are available and link this to the user interface in
Multicon Gyda.
5.1 An overview of the data path
HD/SD-SDI input is selected from input 1 or 2, equalized, re-clocked and transferred to
a processing unit. Here the signal is first sent through a de-glitcher that cleans up
errors that might appear on input signal, e.g. from switching. After the de-glitcher the
parallel video is split in two paths, one going directly to a frame-store buffer, the other
sent to the audio de-embedder.
The 16 audio channels coming from the de-embedder are bundled in pairs and sent to
an audio store buffer (being the same as the frame store buffer). The audio is fetched
from the audio store buffer according to a user specified delay (can be different for
each of the two video inputs) and sent to the Audio Processing Block, where the paired
channels may have gain adjusted (also specific for each of the video inputs). After the
audio processing block the audio enters the Audio Embedder to be re-embedded.
The video (with audio still inserted) is fetched from the frame buffer with the user
specified delay and sent to a Video processing block (which performs the video fading),
followed by an EDH processing block. After the EDH block the video and audio is
embedded according to the user settings and the video is sent from the processing unit
to a re-clocker. Here the signal is converted back to SDI and sent to a 2x2 buffered
output switch.
The output switch is a 2x2 cross point selecting between a signal which has only been
equalized and re-clocked (
“Through”) and a signal which has been fully processed
( “Processed”). The two output signals are each sent to two paired (non-inverting and
inverting) outputs.
5.2 Video input selection and fading
The PGM-HD-2X1-PB has two equivalent electrical inputs. The active input can be
selected directly from the graphical user interface, or input control can be handed over
to the GPI input lines. 5 configurable delays are used to control how the fading
between the two physical inputs appear. The “fade in” settings control how many video
frames will be used to go from “black” to “full luminosity”, while the “fade out” settings
control how many video frames will be used to go from “full luminosity” to “black”. A
user specified number of black frames can also be inserted between the “fade out” and
the “fade in”.
When an input is selected, for instance “Fade to 1”, the actions performed will depend
on the current state of the module. If the module already has input 1 selected, no
actions will be performed. If the module has been forced to black, input 1 will
immediately start to fade in according the “Input 1 fade in” setting (see below). If the
has input 2 selected, output 2 will immediately start to fade out according to the “Input 2
fade out” setting. Once the fade out is completed, a number of additional black frames
will be inserted according to the “Additional black frames” setting. Then the fade in of
input 1 will finally commence according to the setting in “Input 1 fade in”.
When selecting “Fade to 2”, the explanation above still holds if “1” is substituted for “2”
and vice versa.
If “Fade to black” is selected, no actions will be performed if the module is already set
to black. If one of the physical inputs has been selected, the video will fade to black
according to “Input 1 fade out” or “Input 2 fade out” respectively, and then stay black