Video Timing
In detail, each line (horizontal frame or HFrame) consists of:
- scanline, when beam is unblanked, and moving steadily to the right
- front porch, when beam is blanked, and moving steadily to the right
- sync pulse, when beam is blanked, and moves rapidly back to the left
- back porch, when beam is blanked, and again moving steadily to the right.
The porches and associated blanking are to provide fall time and settle time for the beam to move back to the left (the voltage to decrease), and for ringing to die down. The vertical frame (VFrame) consists of exactly the same components, but only occurs once per image frame, and the times are considerably longer. The details of these intervals are called the video timing. See Video timing details revealed for a diagram of these. These are mostly not visible to end users, but were visible in the case of XFree86 Modelines, where users of XFree86 could (and sometimes needed to) manually adjust these timings, particularly to achieve certain resolutions or refresh rates.
Read more about this topic: Raster Scan
Famous quotes containing the words video and/or timing:
“We attempt to remember our collective American childhood, the way it was, but what we often remember is a combination of real past, pieces reshaped by bitterness and love, and, of course, the video past—the portrayals of family life on such television programs as “Leave it to Beaver” and “Father Knows Best” and all the rest.”
—Richard Louv (20th century)
“A great man always considers the timing before he acts.”
—Chinese proverb.