on i.MX6 platforms, intermittent gst pipeline failure is observed

[bvacaliuc]

Using a video-stream.conf as follows:

[Service]
UDP_IFACE=eth0
UDP_HOST=172.20.255.255
UDP_PORT=5600
URL="udp"
FLAGS=h264,mjpg,udp
AUDIO=
LATENCY_MS=
PLATFORM=IMX6

Using no camera input (videotestsrc), we observe normal behavior. I edited the .conf file to switch the IP address and restarted the service but did not see network streaming. Performing the following showed the reason:

$ systemctl restart video-stream
mxc_vpu 2040000.vpu_fsl: VPU interrupt received.
$ ERROR: v4l2 capture: slave not found!
$ journalctl -fu video-stream
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: BEGIN TEST 1280 720 30/1 1800 kbps /tmp/gst.cmd.7594
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: GST_DEBUG=1 G_DEBUG=fatal-criticals gst-launch-1.0 videotestsrc is-live=true ! "video/x-raw,format=(string)I420,width=(int)1280,height=(int)720,framerate=(fraction)30/1" ! timeoverlay halignment=left valignment=top ypad=95 ! textoverlay halignment=left valignment=top ypad=60 name=overlay text="imxvpuenc_h264 bitrate=1800 idr-interval=60" ! textoverlay halignment=left valignment=top ypad=25 text="gst-launch-1.0 version 1.10.4, 1280 x 720 @30/1" ! imxvpuenc_h264 bitrate=1800 idr-interval=60 ! "video/x-h264,stream-format=(string)byte-stream,width=(int)1280,height=(int)720,framerate=(fraction)30/1" ! h264parse ! tee name=t t. ! queue max-size-time=67000000 leaky=upstream ! rtph264pay config-interval=10 pt=96 ! mux.sink_0 rtpmux name=mux ! udpsink host=172.20.255.255 port=5600 t. ! queue max-size-time=67000000 ! progressreport ! fakesink
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: Setting pipeline to PAUSED ...
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: Pipeline is live and does not need PREROLL ...
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: Setting pipeline to PLAYING ...
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: New clock: GstSystemClock
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: Caught SIGSEGV
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: exec gdb failed: No such file or directory
Apr 29 12:08:42 IMX6ee65ef191d1f39d4 video-stream.sh[7594]: Spinning.  Please run 'gdb gst-launch-1.0 7655' to continue debugging, Ctrl-C to quit, or Ctrl-\ to dump core.

Simply restarting the service produces the same pipeline and it operates. The issue is that this particular error is undetectable by systemd, which is already setup to restart the service upon a failure. I wonder if it has to do with the GST_DEBUG environment settings? That would be a workaround, but the root cause is still that the pipeline crashes due to previous work-in-progress that has not been flushed correctly/completely.