[vlc-devel] [PATCH v4] linux: kernel mode setting (KMS) vout plugin

Thomas Guillem thomas at gllm.fr
Fri Jun 29 15:12:43 CEST 2018

On Thu, Jun 28, 2018, at 14:33, Juha-Pekka Heikkila wrote:
> On 26.06.2018 16:08, Thomas Guillem wrote:
> > Hello,
> > 
> > This plugin is well written. This is a very good start for DRM support into VLC. Personally, I would love to have OpenGL support with DRM, by using our OpenGL vout with a DRM window plugin and the EGL DRM extension.
> > 
> I was earlier talking with Remi about this, I see this kind of change as 
> 'v3' of this plugin..as in v1 is this bare bones working on with the 
> basics. If there are special nuances found in some platform which I 
> don't have access it will be easier to hunt down and fix problems. V2 is 
> where mix in DRM features which can make a difference. At least with 
> scaling done on display HW can be made gains on power usage as well as 
> performance and its all totally free. V3 would be where add features 
> which start to change things. Though, I still don't know what is the 
> benefit of having OpenGL here? Remi tried to explain it to me but I 
> understood from him the gain is limited because DRM is full screen only.

We prefer having a GL, D3D (or VK soon) based vout in order to apply GPU filters, like the one used to render 360° videos for example.
A vout without shaders won't be capable to render such videos in a good way. 

> > I was able to test it and have one remarks:
> > 
> > Why do you set the DRM master mode (drmSetMaster()) ?
> > It forces to run VLC as root. I tried to remove this part and was able to run your plugin as a normal user (with video group perm).
> > 
> > Maybe you should not fail if drmSetMaster fails ?
> > 
> I had chitty chatty with my friend who know how DRM rights management 
> work and it turn out I can just drop the request for becoming drm 
> master, these rights are given automatically for my process or otherwise 
> I get error on one of my drm requests. This will also drop need for 
> root. I still need to try on how it work out in reality.

So, I can remove this master part and push ? Agree ?

> /Juha-Pekka

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