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2–12 • System Architecture Synergy Q/MD Engineering Manual (v9.1 MD)
Video Formats
The Synergy Q/MD switcher can operate in a number of different video formats, at different
frequencies in either interlaced or progressive scan mode. When you switch between these formats,
various displays and settings automatically change to show the new information. To better understand
what is being displayed, you must first understand what the information for the different video
formats means.
The video formats that are displayed on the Synergy Q/MD switcher provide three pieces of
information about the video format. This information is the number of horizontal Scan Lines, whether
the scan lines are Interlaced (i) or Progressive (p), and the Frequency that the scan lines are drawn at.
Horizontal Scan Lines
The number of horizontal scan lines is related to the pixel resolution of the image on screen. For
example, if you have a 720p 59.94 video signal, the 720 is the number of vertical scan lines. A video
signal with 720 scan lines usually corresponds to a 1280×720 (H×V) pixel image. This means that the
image is comprised of 1280 columns of pixels and 720 rows of pixels. The reason the vertical
resolution, the 720, is used to denote the video format is because of how it is drawn on a standard
television. With Cathode-Ray Tube (CRT) television monitors, the image is created, or drawn, one
pixel at a time, in rows, from the left side of the screen to the right, to create one scan line.
Scan Lines Example — 1280×720
Since each scan line starts from a vertical pixel, there are 720 rows of pixels, or scan lines, being
drawn horizontally. The same is true of a video signal with 1080 vertical scan lines, which
corresponds to a 1920×1080 pixel image.
Interlaced vs. Progressive
In the previous section we learned that a video signal is made up of a number of horizontal scan lines
that are drawn from left to right on the screen. Although these scan lines are always drawn from left to
right, they can be drawn in either an Interlaced or Progressive pattern.
Interlaced
An Interlaced video format starts at the top of the screen and draws all the odd number scan lines and
then all the even number scan lines in sequence. This results in half the image being drawn in one pass
Scan Lines Interlaced
or
Progressive
Frequency
1080i 59.94
1280
Scan Lines
720