4ac9f91921
alphacombine element is a simple element that assumes buffers are always paired, or at least that missing buffers are signalled with a GAP. The QoS implementation in the GstVideoDecoder base class allow decoders dropping frames independently and that could lead to stall in alphacombine. Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2326>