d to configure FFmpeg with <code>--enable-opengl</code>.
</p>
<p>This output device allows one to render to OpenGL context.
Context may be provided by application or default SDL window is created.
</p>
<p>When device renders to external context, application must implement handlers for following messages:
<code>AV_DEV_TO_APP_CREATE_WINDOW_BUFFER</code> - create OpenGL context on current thread.
<code>AV_DEV_TO_APP_PREPARE_WINDOW_BUFFER</code> - make OpenGL context current.
<code>AV_DEV_TO_APP_DISPLAY_WINDOW_