Epiphan VGA2USB Pro - Manual (Page 49)

11. About Epiphan frame grabbing technology Glossary of Terms
User Guide Page 49
Next a VGA mode describes the timing of the horizontal signals.
These horizontal timings define how the data that makes up each
line is transmitted. The line begins with the active area, which
contains the RGB values for each pixel in the line. The active area
is followed by a blanking region that contains black pixels. Inside
the blanking interval, a horizontal sync pulse is transmitted to
keep the signals synchronized. The blanking interval before the
sync pulse is called the front porch, and the blanking interval after
the sync pulse is called the back porch. The time between
horizontal sync pulses is called the sync time. The sync polarity
designates whether the sync pulse is positive or negative.
The vertical timings work the same way to define how the data
that makes up each frame is transmitted. A frame begins with the
active video area that contains all of the lines in the frame. The
vertical signal also includes a vertical synch pulse that is timed
according to the vertical sync time. The vertical blanking intervals
are also called the front porch and back porch. Finally the vertical
synch polarity designates whether the vertical sync pulse is
positive or negative.
Video capture application
The Epiphan software that intercepts the frames (images) sent by
the Frame Grabber over the USB connection. Using the video
capture application you can display, print and record captured
frames. You can also use the video capture application to transmit
captured frames over the Internet.
Video capture workstation
A computer running Windows, Mac OS X or Linux that you can
use to record captured frames. You connect your Frame Grabber
to the video capture workstation with a USB connection. You
must also install the Epiphan video capture application on the
video capture workstation. If the video capture workstation can
connect to the Internet you can use the video capture application
to broadcast captured images over the Internet.