Using nvoverlaysink to overlay two input streams

Hi,

I investigated the nvoverlaysink but didn´t manage to overlay two camera streams. Is there an example how to use the plugin for this purpose?
I saw use cases in the GStreamer documentation but none that matches my needs.

I need something like this:

gst-launch-1.0 -e -v nvcamerasrc fpsRange="60.0 60.0" sensor-id=0 ! 'video/x-raw(memory:NVMM), width=(int)480, height=(int)640, format=(string)I420, framerate=(fraction)60/1' ! nvoverlaysink overlay=1 overlay-depth=0 overlay-depth=1 & gst-launch-1.0 -e -v nvcamerasrc fpsRange="60.0 60.0" sensor-id=1 ! 'video/x-raw(memory:NVMM), width=(int)480, height=(int)640, format=(string)I420, framerate=(fraction)60/1' ! nvoverlaysink overlay=2 overlay-depth=1 overlay-x=100 overlay-y=200 overlay-w=1024 overlay-h=760

but i get lots of this errors:
0:00:09.847386844 9610 0x6558a0 ERROR omx gstomx.c:268:gst_omx_component_handle_messages: yuv420 got error: Insufficient resources (0x80001000)

This would be a first test overlaying two opaque images. What I actually would like to do is to use the overlaysink to blend the two streams with tramsparency. How can I do this?

Thank you.

Please refer to
https://devtalk.nvidia.com/default/topic/1035520/jetson-tx2/nvoverlaysink-issue-on-tx2/post/5261061/#5261061