[vlc-devel] [PATCH] Add MacOSX OpenGL callbacks to enable Syphon broadcast

Felix Paul Kühne fkuehne at videolan.org
Tue May 15 13:21:53 CEST 2018

Hi Adam,

Thanks for the patch.

> On 14. May 2018, at 19:21, adampcc at runbox.com wrote:
> From: Adam Fedor <afedor at t1v.com>
> This is a fairly simple patch that adds callbacks to the MacOSX OpenGL 
> rendering so that VLC output can be broadcast using Syphon (I imagine 
> there are other uses for the callbacks, but that is not my purpose). I
> know other people are interested in this as well (See 
> https://github.com/rsodre/VLCSyphon and 
> http://v002.info/forums/topic/vlckit-to-syphon/)
> I am not quite sure I'm using the right method to get the size of the
> display output, so any help with that is appreciated.

Supporting Syphon would be an interesting addition, however I’m not sure if the proposed patch is the straight way to go. Calling both additional functions every time a frame is drawn seems very expensive to me as this can be up to 120 times/s, but chances are very low that the vout size actually changed.

In fact, VLC’s video output size depends on the container view size. It’s exactly the same, so I’m a bit puzzled why you need that info since you define the dimensions of the container view yourself. Further, is it intrinsic to the Syphon protocol to be notified every single time the OpenGL context is being updated? That seems weird to me.

Best regards,


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