render quality / loss in recorded movs

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    Hello / been using Syphon with VDMX for a week or so now – thanks so much for such an incredible leap forward in realtime video art !!!

    – I have question which I don’t know if should be directed at VDMX or Syphon – but heres the issue:

    I’m loading high quality photojpeg clips into VDMX -> mixing using CoreImage composite modes – mostly Addition – and fading opacity on 4 layers – > recording output via Syphon to fast SSD.

    When using Syphon, I’ve tried a bunch of different codecs: Prores 4:2:2 , None, AIC, etc –

    the same thing keeps occurring: any soft gradient areas of image are banding severely.

    almost like the different between a 8bit & 16bit render.. however, the movies are all 8 bit and look great standalone.. (rendered from AE) .. only after compositing outputting from VDMX, and recording with Syphon do they end up very “banded” looking //

    I can provide side by side example screenshots if anyone is interested, but just wonder if theres a loss that happening on the canvas in VDMX, or once it gets to Syphon?

    hope this makes sense, its a subtle thing, but critical since the glows/gradient areas are important aesthetic in the clips..

    Any suggestions?

    Is there a definite reduction in bit / quality happening somewhere in this workflow ?

    Possibly how one of the 2 programs output/render?

    I’ve tried changing many of the settings in VDMX and my monitor does not look as banded as the recorded Syphon movie..

    thanks in advance for any input or suggestions!



    This is an effect of the recording stage.

    For most codecs the frames are encoded as 4:2:2 Y’CbCr which involves chroma subsampling. We use a shader for the pixel-format conversion which I’m working to improve at the moment – the current release is not perfect. If you can link to an image of a single frame or e-mail me one I can include it in our tests. I can also send you a new version of Recorder in a few days which it would be good to get feedback on –

    If you have them installed, you could see what results you get with Apple ProRes 4:4:4:4 or Sheer RGB[A] 8bf which will both take different paths. Sheer RGB[A] 8bf should be a perfect match for the source. You can download a trial of the codec at


    thanks for the reply / I’ll email you some example frames –
    also, I’m going to do some tests with Sheer & ProRes 4:4:4 – i’ll post results if theres any improvements.

    also, I’d def test the updated Record and provide feedback for you / send me link when its ready!

    thanks again!


    when you recommended Sheer – do you recommend for the entire workflow:

    convert my video lib to Sheer RGB[A] 8bf ->
    load / playback / output in VDMX – >
    AND use Syphon Recorder with record codec set to Sheer Codec?

    havent tried that yet, so just was curious if thats what you were recommending


    No, just use it at the recording stage.

    It involves considerably higher data rates so performance will be worse – but you should see an exact match with your source material.

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