472d528ffe
When the number of input channels changes, application might have to set a new mix-matrix. Application must set the new matrix before audioconvert receives updated caps, otherwise negotiation would fail. That means it should be allowed to set an invalid mix-matrix until we receive new caps or next buffer. This fixes a regression in GStreamer >=1.24.9 caused by: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7363 Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9215>