I want to use a looped video clip as my webcam source in a Google+ Hangout. I installed v4l2loopback and created a video loopback device. But I haven't figured out how to write the video frames to the device. The given example is:

gst-launch videotestsrc ! v4l2sink device=/dev/video1

So after reading the manual page for gst-launch and trying to understand what was going on, I made my feeble attempt:

sudo gst-launch-0.10 filesrc location=/home/briankb/Videos/darthvaderdancing.mp4 ! v4l2sink device=/dev/video0

Which resulted in:

Setting pipeline to PAUSED ...

libv4l2: error getting pixformat: Invalid argument

Pipeline is PREROLLING ...

Pipeline is PREROLLED ...

Setting pipeline to PLAYING ...



(gst-launch-0.10:12622): GStreamer-CRITICAL **: gst_caps_get_structure: assertion `GST_IS_CAPS (caps)' failed

New clock: GstSystemClock



(gst-launch-0.10:12622): GStreamer-CRITICAL **: gst_structure_get_name: assertion `structure != NULL' failed

Caught SIGSEGV accessing address (nil)

#0  0x00007fc1890f0b03 in poll () from /lib/x86_64-linux-gnu/libc.so.6

#1  0x00007fc18962bff6 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0

#2  0x00007fc18962c45a in g_main_loop_run ()

#3  0x00007fc189b5c4cb in gst_bus_poll ()

#4  0x0000000000404587 in ?? ()

#5  0x0000000000403c34 in ?? ()

#6  0x00007fc18902b76d in __libc_start_main ()

#7  0x00000000004043bd in ?? ()

#8  0x00007fff88253ed8 in ?? ()

#9  0x000000000000001c in ?? ()

#10 0x0000000000000006 in ?? ()

#11 0x00007fff882548c4 in ?? ()

#12 0x00007fff882548d4 in ?? ()

#13 0x00007fff882548dc in ?? ()

#14 0x00007fff88254904 in ?? ()

#15 0x00007fff88254906 in ?? ()

#16 0x00007fff8825490f in ?? ()

#17 0x0000000000000000 in ?? ()

Spinning.  Please run 'gdb gst-launch 12622' to continue debugging, Ctrl-C to quit, or Ctrl- to dump core.

The clip I'm trying to use an h264 video at 29.97 fps, 320x240, and in an mp4 container (it's from Youtube).