Posted by Rick Merrill on 10/03/05 15:59

Mike Kujbida wrote:
>
> Rick Merrill wrote:
>
>>Mike Kujbida wrote:
>>
>>
>>>If you're familiar with the chromakey technique (think TV weather
>>>person), then this analogy will help.
>>>The "key" is the hole that is cut (what's left of the greenscreen,
>>>excluding the weather person, after some electronic adjustments are
>>>made) and the fill is what replaces the green screen (satellite map,
>>>location shot, etc.). Does that help?
>>>
>>>Mike
>>>
>>
>>So why would one want the key(hole) to be on one channel and the
>>fill(background) on another? How would this be used to put a 'bug' on
>>screen?
>
>
>
> The key typically has something called an alpha (transparent) channel. This
> means that anything NOT part of the 'bug' will not be seen. The 'fill'
> (backgound) is what is being keyed over top of. Assuming the key is a title
> or station logo, it could thenbe place over the program stream without
> anything else in the key showing. For example, I use a lot of logos that
> are on a plain white background. I bring them into Photoshop and make the
> white background transparent. This way, I cam now 'key' the logo over top of
> anything I want.
> The following links may help explain what an alpha channel is:
> http://www.ttop.com/how_to_alpha.html
> http://www.digitaljuice.com/techsup/alphachannels.asp
> Does that help or further muddy the waters?
>
> Mike
>
>
>
>>>The 2000 will support a “Key/Fill” mode for
>>>Targa frames, (automatic)
>>>MPEG-2 files, and (user)
>>>DV files. (user)
>>>
>>>For example, loading a file named "Logobug" on Channel 2
>>>automatically loads the Logobug_ (Alpha Clip) onto Channel 3.
>>>
>>>For Targa files, the alpha clip name will be generated automatically
>>>during ingest via FTP. For DV and MPEG files, the user must
>>>use the same name as the 'fill channel' and explicitly save the alpha
>>>clip adding the underscore to the end of the clip – all prior to
>>>transfer.
>>>
>>>In Key/Fill mode, the transport controls of Channel 2 will
>>>control Channel 3, allowing 1x frame-synced playback of both Key and
>>>Fill channels. This mode will be invoked by clicking a check box in
>>>the GUI. Channel 1 will be available, as usual, for either playout or
>>>record. When not in Key/Fill mode, either file may be played back as
>>>a standard clip file.
>
>

The creation part is clear, but I'm baffled by the actual broadcast
portion of putting those files on the air!

to wit:
"the transport controls of Channel 2 will
control Channel 3, allowing 1x frame-synced playback of both Key and
Fill channels. This mode will be invoked by clicking a check box in
the GUI."

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