render quality / loss in recorded movs

[naoism]

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!

[bangnoise]

Yo

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 – bangnoise@gmail.com

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 http://www.bitjazz.com/en/products/sheervideo/

[naoism]

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!

[naoism]

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
thanks!

[bangnoise]

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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