Certain encoder user controls as well as codec controls can be changed while the pipeline is in playing state. e.g. Codec controls like video_bitrate, frame_ltr_index, use_ltr_frames, etc. and user controls like horizontal_flip, vertical_flip can be changed while the pipeline is running. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9168>