bool should_quit = false;
RefCountedFrame new_frame;
int64_t new_frame_length; // In TIMEBASE units.
+ unsigned new_frame_field; // Which field (0 or 1) of the frame to use.
GLsync new_data_ready_fence; // Whether new_frame is ready for rendering.
std::condition_variable new_data_ready_changed; // Set whenever new_data_ready is changed.
unsigned dropped_frames = 0; // Before new_frame.