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View Full Version : TC Broadcast and Alpha out



bob anderson
07-02-2010, 05:34 PM
Hi all. A few months ago I'd posted asking if anyone had had any luck getting a 32 bit, or 24+8 file out of green screen footage in TC-speed edit, or standalone. I'd only ever gotten totally unacceptable results, which is disappointing since the live keyer does such an excellent job.

Then I happened upon the configure panel on the TC Broadcast, and remembered that there is an option of sending an alpha out through the preview out. I popped open the manual ( the "TriCaster Family" version ) and found that ( on page 106 ) there is no mention of the various output modes whatsoever.

I plugged the SDI preview out into input 3 SDI so I could see what the output looked like. Setting up a key page in the DSK, and setting the preview out to show the DSK Alpha out worked as I'd expected. I set up my green screen, and turned on the keyer. Setting the preview to Main Out alpha, I never saw anything. I was hoping it would give me the clean alpha I was looking for. ( which ultimately I'd save onto some other media through the SDI out, and later "marry" to the beauty pass )

Am I barking up the wrong tree trying to get the alpha from the main out by setting the output to "main out alpha"? Can anyone explain what I should be seeing from that main out alpha output, and how one would use it?

Thanks

Bob Anderson

SBowie
07-02-2010, 06:15 PM
Then I happened upon the configure panel on the TC Broadcast, and remembered that there is an option of sending an alpha out through the preview out. I popped open the manual ( the "TriCaster Family" version ) and found that ( on page 106 ) there is no mention of the various output modes whatsoever.Bob, in my current copy, page 106 is a table of Edit Pane capture connection options. The Broadcast output configuration options are discussed on page 101, but no mention of Alpha - largely because there was no Alpha out option at the time it was written. VT[5] had one, but if it's in BC now too it's news to me. Love to see a screenshot of the configure panel.

bob anderson
07-02-2010, 06:27 PM
My page 101 is on the audio panel. Here's a screen shot.

What should I see on the Main out alpha, and will it do what I need? I was fooling around a bit more, and figured out I can use the key "preview" on the input setup tab to output a white over black image, but I don't think it contains the actual 8 bit alpha data.

Bob Anderson

SBowie
07-02-2010, 07:16 PM
Fascinating. My guess would be it's similar to the VT[5] Alpha Output, which as I understand it sends the alpha from the Program row out the designated output. I note the VT manual adds that Genlock is required for Alpha to work - presumably to match the timing of the downstream system. This is probably not relevant to your machinations, though.