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Exporting QT with alpha
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[Rafael Amador] “Hi Tod,
Sorry to disagree with you. if you render you still exporting with Alpha channel. If you lose the Alpha, you may have something set wrong.
rafael”Nope, the only way to render an alpha out of FCP is if it is not rendered. Try for yourself.
-mattyc -
Is there a checkbox somewhere for “premultiplied alpha” to uncheck?
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[Rafael Amador] “Hi Tod,
Sorry to disagree with you. if you render you still exporting with Alpha channel. If you lose the Alpha, you may have something set wrong.
rafael “The issue is not rendering so much as what codec is in use in the timeline that the clips is being rendered to. If the timeline is rendered, all you ned up doing is exporting the rendered media. Even if you export using the Animation codec and call for the alpha, if the source media has not alpha, it will NOT be created unless the effect is unrendered first.
Apple’s decision to build the whole FCP export process is weirdly lame. Exporting with or without alpha is of a standard video editing tool. Even Ye Olde Media 100 had a convenient and intuitive export dialog.
bogiesan
This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”
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Mark,
FC only export Strait Alpha. No option to choose Premultiplied.[david bogie] “Even if you export using the Animation codec and call for the alpha, if the source media has not alpha, it will NOT be created”
Thats clear. if there is not any transparency is impossible to get an Alpha channel whatever the codec you choose. But if you import two clip with Alpha and you compose them in a sequence with a codec with Alpha, on export you get the Alpha and the sequence have been rendered.
rafael -
Yes, one can render or not render and will still get an alpha based QT by exporting a codec that supports them. I just did this in a rendered DV NTSC sequence just to make sure. I have no idea why some people seem to have problems. Different versions of FCP perhaps?
I am not sure about the straight only being exported from FCP. I just did both Animation and PNG QT outputs to test. While a program like AE guesses them to be straight, they actually seem to be pre-multiplied on black. Otherwise one gets black fuzz on soft edges of PIP effects, etc. If one chooses premultiplied on black, they are interpreted correctly. Something to do with the QT wrapper changing the PNG straight for some reason. Weird. Wish I could just Export Image Sequences from FCP to avoid the muddling 2-step procedure.
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[Kevin Downer] “I am not sure about the straight only being exported from FCP. “
Hi Kevin,
Neither I’m sure. I thought they were Strait because (I tried) when you export from FC with Alpha, and re-import that to FC, the Alpha it shows up as Strait in FC’s Browser and works fine with this setting.
What I don’t know is who FC manage the different kind of Alphas no having an option to Pre-De-Multiply.
And if can arise the same issues that happens, for examle, when applying a CC filter to a Premultiplied Alpha channel in AE or Shake.
rafael -
[Kevin Downer] “Yes, one can render or not render and will still get an alpha based QT by exporting a codec that supports them. I just did this in a rendered DV NTSC sequence just to make sure. I have no idea why some people seem to have problems. Different versions of FCP perhaps?”
I’m always interested in learning how to do new stuff. You are performing an additional step I do not know how to perform.
If you drop a clip that is transparent onto a DV timeline and there is something underneath it that is not transparent and you render the timeline and then set in and out points around the transparent clip to designate just that area of the timeline to be exported there is no way to tell FCP to unrender the clip unless, of course, you are doing something I don’t know how to do.bogiesan
This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”
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I guess I’m not sure what you would be trying to accomplish here.
FCP seems to treat the function very much like After Effects. If one had a layer covering the whole area and something with an alpha above it, both programs would provide an alpha: It just would not be of any use. In AE, one would have to “Shy” a video clip underneath and in FCP, one would “Hide” the layer.
To get around the problem of losing one’s entire rendered timeline, one could Subclip the section of the sequence and then delete or hide the underlying video clip of that sub-sequence, export a QT with Alpha, and then re-import to replace that section of the sequence.
That is what the original person posting seemed to be trying to achieve. The issue seemed to be if it was rendered, one could not export an alpha which is not the case.
If one had the same setup layers in AE as you described in your example FCP sequence, the same situation would arise, unless one hid the underlying video clip.
Basically, if you can’t see a defining alpha displayed in FCP when switching views in the Record window, one will not successfully be able to export a useful alpha.
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[david bogie] “onto a DV timeline”
On a DV time-line, obviously there is nothing to do. The sequence needs a codec supporting Alpha.
You drop two Animation objets with Alpha in a sequence set with Animation-Millions+, and you will export an object with the combined Alpha. -
Hi Matt,
I’ve been trying to do that, but I’m unable.
I pick a DV clip, put it in a DV sequence. Crop it and rotate, so do not cover the full canvas and needs to be rendered.
When I export (No render, QT Conversion) and re-import to FC, i get no Alpha nowhere.
Am I missing something?
I’m in FC 6.0.4
Rafael
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