VLC 4.0 OpenGL shared context

[neosettler]

Greetings,

I'm in the midst of rendering directly to an OpenGL texture buffer using libvlc_video_set_output_callbacks (VLC 4.0 beta) implementation. The way my API is setup, I use QT for GUI while VLC is implemented in an external dynamic library (dll). Since the main OpenGL context is create by QT and that VLC is unawarded of QT, I'm unable to switch context (within VLC callbacks) as QT and VLC contexts are on different threads. I'm clearly facing a design problem but I'm not sure how to solve this. I'm open to suggestion or maybe some example to chew on would be nice.

Thank you,

[mfkl]

https://github.com/videolan/vlc/blob/master/doc/libvlc/sdl_opengl_player.cpp

[chubinou]

Hi,

rather this sample https://code.videolan.org/videolan/vlc/tree/master/doc/libvlc/QtGL
which shows how to use libvlc_video_set_output_callbacks with Qt.

[unidan]

Basically, libVLC is a multimedia pipeline that doesn't get synchronization input from your app (because you shouldn't have to handle that). But your app is probably not synchronized by VLC pipeline. So you have to do the synchronization between both of them yourself like in the QtGL example. As your application might be rendering frame at a different speed than VLC, you need triple buffering to achieve clock syncing without glitches between the two clock domains.
The other solution is to slave your application into VLC's pipeline, thus enforce the framerate of your application, but without filtering in VLC it might be different than 60 fps for example so I would advise against for now.

[onelistme]

https://github.com/videolan/vlc/blob/ma ... player.cpp

I try this example, however it not works well as expect. Here is more informaiotn https://forum.videolan.org/viewtopic.php?f=14&t=155928
Is there more inforamation about this example.

[unidan]

Hi, I'll suggest that we move to the other topic you opened then.