Re: Why 1080i?

On Wed, 24 Aug 2005 21:50:58 +0000 (UTC) Tim Mullen <tim@xxxxxxxxx> wrote:

|>|>The "Psf" means what (I don't know this acronym or designation)?
|>|
|>| Progressive Segemented Frame. The progressive scanned frame of
|>| video is presented as two interlaced fields. The difference between
|>| this and a normal interlaced signal is during capture. With Psf it's
|>| guaranteed there is no motion between field one and field two.
|>|
|>| I've heard various reasons for the introduction of Psf over good
|>| old P (normal progressive). One rumor says it was started by a certain
|>| major manufacturer's inability to provide sufficient outbound framestore
|>| on some of their products, others point to bandwidth reduction.
|
|>That would seem to convert (back) to P easier.
|
| Don't misunderstand me -- Psf *is* progressive scan. It differs
| from "pure" P simply by the order in which lines are transmitted.
| Pure progressive would hand you line 1, line 2, line 3 ... Psf gives
| you all the odd lines first, then all the even lines.

I think I understand you. Shoot with progressive, buffer a whole frame,
and transmit as interlaced. Receive interlaced, buffer a whole frame,
convert to progressive for whatever purposes progressive is good for.

|>Things probably edit a lot easier that way, too.
|
| Doesn't make a difference.

Still frames and such, where there is a lot of motion, can look ugly
with interlaced. You either live with the stripes, or synthesize a
frame from one field. PSF would seem to avoid that issue by giving
you two fields that pair up without the effects.

But how about the quality of compression of pure P vs. PSF?

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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
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