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Importing and Exporting Alpha Channel

4113 Views 32 Replies Latest reply: Mar 31, 2012 12:06 AM by fox_m RSS
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Sullyville Calculating status...
Currently Being Moderated
Mar 27, 2012 2:09 PM

Hi,

 

I have a Flash video (FLV) with an alpha channel (I don't have access to the original QT video). I used Adobe Media Encoder to convert it to Quicktime to import into FCP X to make a quick edit and export back out. How do I ensure that the video imports into FCP X with the alpha channel and exports back out with the alpha channel? I set Adobe Media Encoder to encode the alpha channel, but how can I tell if it imports into FCP with the alpha and exports back out with the alpha? Is there a way to check that in FCP? After I exported it out of FCP, converted it back to FLV and imported it into Flash, it no longer had the alpha channel. Not sure where I lost it along the way. When I exported out of FCP, I chose Apple ProRes 4444.

 

What things do I need to make sure I do in each of these converts, imports and exports and how can I tell if the alpha channel is there in FCP X?

 

Thanks,

 

Brian

  • dredcomm Level 2 Level 2 (360 points)
    Currently Being Moderated
    Mar 27, 2012 2:29 PM (in response to Sullyville)

    The top right corner of the Viewer in FCPX has a dropdown menu where you can select what Channel to view.  You can choose the Alpha Channel there.  ProRes 4444 and Animation are both codecs you can use within the .mov format to retain an alpha channel.

     

    ~D

  • dredcomm Level 2 Level 2 (360 points)
    Currently Being Moderated
    Mar 27, 2012 2:40 PM (in response to Sullyville)

    If it's all white then there is no alpha.  You probably lost it in the encoding process.

     

    Try encoding to an Animation or ProRes4444 QuickTime movie with an alpha.

     

    ~D

  • stuckfootage Level 4 Level 4 (3,040 points)
    Currently Being Moderated
    Mar 27, 2012 3:22 PM (in response to Sullyville)

    You can just use QuickTime Player 7 to convert from .flv with alpha to Animation-Millions+ or ProRes4444.

     

    QuickTime Player 7 should be on your system install disks.

  • stuckfootage Level 4 Level 4 (3,040 points)
    Currently Being Moderated
    Mar 27, 2012 3:51 PM (in response to Sullyville)

    When you install Adobe CS, it should install the Flash components here:

    /Library/QuickTime/FLV.component

     

    If you don't have that component, you can install Perian:

    http://perian.org/#download

  • fox_m Level 4 Level 4 (3,340 points)
    Currently Being Moderated
    Mar 28, 2012 1:18 AM (in response to Sullyville)

    If you converted to QT from the outset from AME, I don't believe the alpha channel exists in the MOV file. You don't say what format you exported to, but anything other than ProRes 4444 or Animation would have "flattened" the video. Alpha channels do not exist in most video codecs including H.264, they're unsupported. Your original Flash w/alpha channel has to be On2 VP6 format. If ProRes 4444 is an option for export in AME - use that! otherwise, QT7Pro with the Perian Component should be able to open up the On2 VP6 file directly. Use QT7Pro to transcode that video into ProRes 4444 (preferred) OR Animation (with the appropriate alpha settings) and try importing that into FCPX. To test for transparency, just drop one of the generators below the storyline under that clip. If there's transparency, you'll see portions of the generator show through.

     

    Exporting from FCPX is the opposite: export at "Current Settings" (should always be ProRes 4444) and use AME to convert it back into .flv format. If AME ignores the alpha channel in PR4x4, use QT7Pro to convert to the Animation (w/alpha) format before using AME.

     

    Without the original QT video, I would prepare myself for a loss of quality :/

  • Luis Sequeira1 Level 5 Level 5 (4,820 points)
    Currently Being Moderated
    Mar 28, 2012 4:29 AM (in response to Sullyville)

    The idea of using QuickTime 7 is a good one.

     

    It is not enough to export in Animation or ProRes 4444 format. Make sure you have also chosen "Millions of Colors+" (note the PLUS sign: this is what indicates that you are exporting an alpha channel). Just "Millions of Colors" does NOT export the alpha channel.

     

    Screen Shot 2012-03-28 at 12.28.03 PM.png

     

    Message was edited by: Luis Sequeira1 to add screenshot

  • stuckfootage Level 4 Level 4 (3,040 points)
    Currently Being Moderated
    Mar 28, 2012 9:38 AM (in response to Sullyville)

    Let's divide this problem into two halves. First of all, are you actually creating a movie with an alpha channel? Instead of testing with FCX, open the movie in Photoshop. You should see the background as a checkerboard pattern.

     

    If not, then you're not creating the movie correctly, and that has nothing to do with FCX.

     

    If you do see the checkerboard pattern, then you are creating the movie correctly and the problem is in FCX.

     

    Once you do that test, we can proceed.

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