Author Topic: what is the diffence between...  (Read 1797 times)


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what is the diffence between...
« on: May 19, 2002, 14:01 »
what is the diffence between "progrssive scan" output and "Double liner"up sampling rate output??............
« Last Edit: May 23, 2002, 10:45 by joamonte »


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Re:what is the diffence between...
« Reply #1 on: May 23, 2002, 10:44 »
push ...

no one can explain??

Offline pschia

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Re:what is the diffence between...
« Reply #2 on: May 23, 2002, 13:37 »
They are essentially the same....

A standard NTSC video signal from a VCR, DVD player (non progressive) or cable/ satellite outputs a 15.75Khz horizontal scanning frequency. This is the "normal" TV that we're used to and is an interlaced signal.  This means that for every scanning pass to produce the image, one line of resolution is skipped. The rest of the picture frame is then scanned in another pass to fill in the missing gaps.  The image of one complete video frame is produced by displaying these 2 half-frames every 1/30 of a second.  This tends to create flicker and jitter in the image.

Line doubling or 480 x 640 from a PC eliminates this by progressively scanning the ENTIRE image all in one pass.  You will see the entire frame of the image all scanned progressively every 1/60 of a second.  The image produced this way is much smoother and more film-like.  Line doubling or 480p requires a display or projector to scan at a faster rate of 31.5Khz. The more lines of resolution fed to a display unit or projector, the faster it need to scan. See table below.

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