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picture phase questions
- To: telecine at sun.alegria.com
- Subject: picture phase questions
- From: bob at bluescreen.com
- Date: Wed, 23 Apr 1997 00:21:05 GMT
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- Reply-To: bob at bluescreen.com
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This may not be the exact right place to look for this info, but there are
a lot of clever engineering minds here, and I have some questions regarding
picture phase (position) in analog recordings.
Specifically, I am interested in the following, applicable to both Beta-SP
and DigiBeta (and please keep in mind that this would take place in a
production environment, not a zero-timed post house):
If I feed a deck with component video and the deck has no reference black
input, picture phase (position) is determined by where the sync is on the Y
channel. If I can control the h-phase of the sync on the Y channel (on a
Grass transcoder, for example), I can to some extent control picture
position. Same if I feed it composite video with no reference in - if I
vary sync timing, picture position varies.
Now, what if I feed the deck a reference black which is different in time
from the sync on the video input (either Y or composite)?
-Does the picture phase (position) now lock to the reference black (which
is not the same h-phase as the picture input sync)? Ie., can I no longer
control picture phase by varying the h-phase of the picture sync?
-If so, is there an internal menu setting or hardware switch on the deck
which enables or disables this?
-Is whatever happens when I feed a reference black to the deck true for
both Beta SP and DigiBeta decks?
And one more question:
If I have two identical zero timed beta component and composite images, and
I feed them one at a time to a Beta SP or DigiBeta deck, are the resultant
recorded picture phases (positions) identical? In other words, is there
any type of internal delay in the decks when the input is composite rather
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