Simplistic fix for silent driver when there's no audio format.  Better to actually deliver video frame events.
Simplistic fix for silent driver when there's no audio format.  Better to
actually deliver video frame events.

niklaskorz/pyglet,adamlwgriffiths/Pyglet,niklaskorz/pyglet,adamlwgriffiths/Pyglet,seeminglee/pyglet64,adamlwgriffiths/Pyglet,niklaskorz/pyglet,seeminglee/pyglet64,niklaskorz/pyglet,adamlwgriffiths/Pyglet,seeminglee/pyglet64