GstQueue Simple asynchronous data queue. Simple data queue. Data is queued till max_level buffers any subsequent buffers sent to this filter will block until free space becomes available in the buffer. The queue is typically used in conjunction with a thread. You can query how many buffers are queued with the level argument. The default queue length is set to 10. The queue blocks by default. Get the number of buffers in the queue. Specify the maximum number of buffers in the queue before the queue blocks.