gstreamer and vivid - error: /dev/video3 is not an output device

liz141414

am trying to use gstreamer with vivid .
the idea is to use vivid to simulate 4 virtaul cameras.
Then, use gstreamer to write images to these virtual cameras.
when i try writing to the device using gstreamer,i get the following error "device '/dev/video3' is not a output device".
I was using the following link to ensure that the devices are set as output devices: https://www.kernel.org/doc/html/v4.14/media/v4l-drivers/vivid.html
details below.
I will appriviate any advise.
Thanks !

1. sudo modprobe -r vivid
2. sudo modprobe vivid num_outputs=4 output_types=0x00
3. v4l2-ctl --list-devices
   result:
   vivid (platform:vivid-000):
   /dev/video3
   /dev/video4
   /dev/video5
   /dev/video6
   /dev/radio0
   /dev/radio1
   /dev/vbi0
   /dev/vbi1
   /dev/swradio0
   /dev/v4l-touch0
   /dev/media1

4. gst-launch-1.0 -v multifilesrc location=./%05d.png loop=1 caps="image/png,framerate=30/1" ! pngdec ! videoconvert ! "video/x-raw,format=YUY2" ! v4l2sink device=/dev/video3
   return error:
   ERROR: from element /GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0: Device '/dev/video3' is not a output device.
   Additional debug info:
   ../sys/v4l2/v4l2_calls.c(636): gst_v4l2_open (): /GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0:
   Capabilities: 0x5230005
   ERROR: pipeline doesn't want to preroll.
   Failed to set pipeline to PAUSED.

5. same for video4,5,6