GstVaapiVideoMemory doesn't allow GST_MAP_WRITE mapping
Submitted by Michał Wróbel
Trying to map the buffer in GST_MAP_READ | GST_MAP_WRITE mode fails with gst.vaapivideomemory unsupported map flags (0x3) at gstreamer-vaapi/gst/vaapi/gstvaapivideomemory.c:436. Is there any particular reason why gst_vaapi_video_memory_map() doesn't just use the same kind of mapping it does for GST_MAP_READ? LibVA documentation  doesn't seem mention that vaMapBuffer-mapped buffers shouldn't be tampered with...