Codecs with Alpha Channel



  • Does anyone know what the best way to bring movies with an alpha channel into Isadora is. I will be playing back several 1280x800 movies at once so I am trying to find a codec that Isadora can play back as efficiently as possible at varying speeds. An admittedly cursory look through the Izzy manual hasn't turned up any official answer to this question although I seem to vaguely remember there being one in it at some point in the past. Any thoughts would be much appreciated.



  • You do not have too many options on mac.

    PNG movie with Millions of Colors+(alpha) works the best for me. File is not too large and playback is not too hungry.
    Animation with alpha is out of the question. I can run 1sec clip maybe without dropped frames. Animation codec was never made for real time playback.
    ProRes4444(with alpha channel) is very good quality if you have fast mac. But the file is pretty big and playing large files is problematic always.
    There is DXV(Resolume codec) that supports alpha as well but only with Resolume and gets excellent frame rate there. Useless outside Resolume.


  • Thanks, Vanakaru. PNG movie it is.



  • for animation, i think it works if you render as Photo-JPEG and then use an alpha channel in Isadora.....

    ....right? 


  • Dear Raha,

    The photo-jpeg codec has no "built-in" alpha channel -- in other words, the alpha cannot be encoded into the movie as it can with the PNG+ and Animation codecs. You can however create add alpha information to a video stream coming from a Photo JPEG movie by using the "Add Alpha Channel" actor. But this usually only helpful if you intend to add a fixed mask. If you want to have your image use a "traveling mask" (i.e., where the mask is moving in sync with the main image) then you need to use the codecs described by vanakaru.
    Best Wishes,
    Mark


  • Hi Mark

    i haven't gotten into traveling masks....so that method works for me...
    regarding Vanakuru's comment "Animation with alpha is out of the question" -- is this true? there's no codec that allows for animation to retain transparency? 

  • Tech Staff

    I think vanakaru meant is, its out of question because of its heavy cpu load. Animation does support alpha channel.

    Best,
    Michel



  • Does anyone know if there's a "best" option for Windows?

    Cheers,

    Hugh


  • Tech Staff

    I would suggest testing the DXV codec on Windows.. It seems that the free version should support alpha.
    http://resolume.com/software/dxv.php



  • @Dusx as much I know the alpha is supported ONLY through Resolume the same as better performance.


  • Tech Staff

    OK< just did a quicktest and I have a DXV quicktime running in Izzy with alpha.
    Just select 'preserve transparency' in the quicktime codec settings during export.
    I have a test file that is 10 seconds 30fps 640x480 @ 17.6 mb
    Seems to run smooth for me, once I set izzies framerate to match the video.


  • Tech Staff

    PS: note Izzy can't be YUV mode



  • @Dusx Great.



  • I tried DXV again(after some years+downloaded the latest codec) and indeed it works very well. I have seen reports of better performance that with PNG+. Even the file is smaller that PNG+.

    When exporting from AE you need to choose RGB+Alpha and then Millions of Color+ along in codec settings to preserve alpha. 

  • Tech Staff

    Glad its working for you.. seems like the best alpha option right now.


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