V4L2 buffer queue orphaning
Recent kernels allow REQBUFS(0) on a queue that still has buffers in use (mmapped or exported via dmabuf), orphaning all buffers on the queue. If this is supported, the v4l2videodec element does not have to send a drain request downstream. This allows to switch resolution of a decoded string without having to wait for the sink to return the last shown buffer of the old resolution.