Hello Today I decided to update my Xavier NX to the jetpack 4.5 from the 4.4.1 , unfortunately, my code don’t run anymore, I have an issue with nvv4l2h264enc that raises a dump if I open my second webcam trough videocapture (python -opencv). My setup : Jetpack 4.5 Python 2.7.17 & Python 3.6.9 Opencv 4.5.2 #the pipelines streamf='v4l2src device=/dev/video0 extra-controls="s,exposure_auto=3,exposure_absolute=300" io-mode=2 ! image/jpeg, width=%d, height=%d, framerate=%d/1, format=MJPG ! queue ! nvv4l2decoder mjpeg=true enable-max-performance=1 capture-io-mode=2 output-io-mode=2 ! nvvidconv ! video/x-raw, format=NV12 ! appsink sync=false' %(camf_w,camf_h,camf_rate) streamb='v4l2src device=/dev/video1 extra-controls="s,exposure_auto=3,exposure_absolute=300" io-mode=2 ! image/jpeg, width=%d, height=%d, framerate=%d/1, format=MJPG ! queue ! nvv4l2decoder mjpeg=true enable-max-performance=1 capture-io-mode=2 output-io-mode=2 ! nvvidconv ! video/x-raw, format=NV12 ! appsink sync=false' %(camb_w,camb_h,camb_rate) cap=cv2.VideoCapture(streamf, cv2.CAP_GSTREAMER) cap2=cv2.VideoCapture(streamb, cv2.CAP_GSTREAMER) # this instance raises the segmentation (jetpack 4.5 only) The error : Opening in BLOCKING MODE Opening in BLOCKING MODE NvMMLiteOpen : Block : BlockType = 277 NVMEDIA: Reading vendor.tegra.display-size : status: 6 NvMMLiteBlockCreate : Block : BlockType = 277 [ WARN:0] global /tmp/build_opencv/opencv/modules/videoio/src/cap_gstreamer.cpp (1081) open OpenCV | GStreamer warning: Cannot query video position: status=1, value=13, duration=-1 Opening in BLOCKING MODE Opening in BLOCKING MODE Opening in BLOCKING MODE Segmentation fault (core dumped) ------------------ (program exited with code: 139) Press return to continue Does someone has the same behavior , and maybe a fix ? I changed my pipelines to use nvjepdec or jpegdec , its works, but the performance is not great Thank you in advance for your support Regards Ludovic

Thank you for your feedback Already done, even with the 4.5.1, same issue

Do these pipelines (using fakesink instead of appsink) work in a single gst-launch command ? gst-launch-1.0 -v v4l2src device=/dev/video0 io-mode=2 ! image/jpeg, width=640, height=480, framerate=30/1, format=MJPG ! queue ! nvv4l2decoder mjpeg=true enable-max-performance=1 capture-io-mode=2 output-io-mode=2 ! nvvidconv ! video/x-raw, format=NV12 ! fakesink v4l2src device=/dev/video1 io-mode=2 ! image/jpeg, width=640, height=480, framerate=30/1, format=MJPG ! queue ! nvv4l2decoder mjpeg=true enable-max-performance=1 capture-io-mode=2 output-io-mode=2 ! nvvidconv ! video/x-raw, format=NV12 ! fakesink If this works, try adding queues before appsinks. You may also try other io-modes of nvv4l2decoder. If this doesn’t work, check the camera modes (I used 640X480p30): v4l2-ctl -d0 --list-formats-ext v4l2-ctl -d1 --list-formats-ext If still not working with a supported mode of the camera, you may post the output of the gst-launch command.

Thank you for your support ;-) unfortunately It does not work (I tried with all resolutions supported) , here is the output ludovic@ludovic-desktop:~$ gst-launch-1.0 -v v4l2src device=/dev/video0 io-mode=2 ! image/jpeg, width=640, height=480, framerate=30/1, format=MJPG ! queue ! nvv4l2decoder mjpeg=true enable-max-performance=1 capture-io-mode=2 output-io-mode=2 ! nvvidconv ! video/x-raw, format=NV12 ! fakesink v4l2src device=/dev/video1 io-mode=2 ! image/jpeg, width=640, height=480, framerate=30/1, format=MJPG ! queue ! nvv4l2decoder mjpeg=true enable-max-performance=1 capture-io-mode=2 output-io-mode=2 ! nvvidconv ! video/x-raw, format=NV12 ! fakesink Setting pipeline to PAUSED ... Opening in BLOCKING MODE Opening in BLOCKING MODE Opening in BLOCKING MODE Opening in BLOCKING MODE Opening in BLOCKING MODE Caught SIGSEGV #0 0x0000007fa77fbd5c in __waitpid (pid= , stat_loc=0x7fff2e3834, options= ) at ../sysdeps/unix/sysv/linux/waitpid.c:30 #1 0x0000007fa78372e0 in g_on_error_stack_trace () #2 0x000000556b344c3c in () #3 0x0000000000008600 in () Spinning. Please run 'gdb gst-launch-1.0 17360' to continue debugging, Ctrl-C to quit, or Ctrl-\ to dump core. --------------------- gdb gst-launch-1.0 17570 GNU gdb (Ubuntu 8.1.1-0ubuntu1) 8.1.1 Copyright (C) 2018 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "aarch64-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: . Find the GDB manual and other documentation resources online at: . For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from gst-launch-1.0...(no debugging symbols found)...done. Attaching to program: /usr/bin/gst-launch-1.0, process 17570 [New LWP 17572] [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/aarch64-linux-gnu/libthread_db.so.1". 0x0000007f8412e5fc in __GI___nanosleep (requested_time=0x7fe154d5c8, remaining=0x7fe154d5d8) at ../sysdeps/unix/sysv/linux/nanosleep.c:28 28 ../sysdeps/unix/sysv/linux/nanosleep.c: No such file or directory. (gdb)

You may issue a backtrace command: bt into gdb when the fault happens in order to get (maybe) some additional information. Also please post the v4l2-ctl command above’s output. Did you try removing the nvv4l2decoder io options ?

Yes, I removed the io options, same issue Here is the output for the formats supported, same output d0 or d1: v4l2-ctl -d0 --list-formats-ext ioctl: VIDIOC_ENUM_FMT Index : 0 Type : Video Capture Pixel Format: 'MJPG' (compressed) Name : Motion-JPEG Size: Discrete 3840x2160 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 1920x1080 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 2592x1944 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 2048x1536 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 1600x1200 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 1280x960 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 1280x720 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 1024x768 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 800x600 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 640x480 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 320x240 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Index : 1 Type : Video Capture Pixel Format: 'YUYV' Name : YUYV 4:2:2 Size: Discrete 3840x2160 Interval: Discrete 1.000s (1.000 fps) Size: Discrete 1920x1080 Interval: Discrete 0.333s (3.000 fps) Size: Discrete 2592x1944 Interval: Discrete 1.000s (1.000 fps) Size: Discrete 2048x1536 Interval: Discrete 0.333s (3.000 fps) Size: Discrete 1600x1200 Interval: Discrete 0.333s (3.000 fps) Size: Discrete 1280x960 Interval: Discrete 0.200s (5.000 fps) Size: Discrete 1280x720 Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 1024x768 Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 800x600 Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 640x480 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps) Size: Discrete 320x240 Interval: Discrete 0.033s (30.000 fps) Interval: Discrete 0.040s (25.000 fps) Interval: Discrete 0.050s (20.000 fps) Interval: Discrete 0.067s (15.000 fps) Interval: Discrete 0.100s (10.000 fps) Interval: Discrete 0.200s (5.000 fps)

So far, I don’t think opencv is really involved, so let’s just try on gstreamer side. Can you get decoded stream from one camera (using first a low mode, you would increase when working) ? gst-launch-1.0 -v v4l2src device=/dev/video0 ! image/jpeg, width=320, height=240, framerate=15/1, format=MJPG ! nvv4l2decoder mjpeg=1 ! nvvidconv ! xvimagesink If working, does the second camera work or give fault from another terminal: gst-launch-1.0 -v v4l2src device=/dev/video1 ! image/jpeg, width=320, height=240, framerate=15/1, format=MJPG ! nvv4l2decoder mjpeg=1 ! nvvidconv ! xvimagesink

The both instances work, even at 25fps 1080p

Do they fail when launched in the same gst-launch command ? gst-launch-1.0 -v v4l2src device=/dev/video0 ! image/jpeg, width=320, height=240, framerate=15/1, format=MJPG ! nvv4l2decoder mjpeg=1 ! nvvidconv ! xvimagesink v4l2src device=/dev/video1 ! image/jpeg, width=320, height=240, framerate=15/1, format=MJPG ! nvv4l2decoder mjpeg=1 ! nvvidconv ! xvimagesink

Unfortunately yes, it failed in the same command

Then, I’m afraid I cannot help further. Anyway, the above info may help someone more skilled to understand your case and better advise. You may monitor kernel messages from another terminal with: dmesg --follow and check if you see USB or else errors when it fails. You may also run: export GST-DEBUG=*:3 gst-launch-1.0 -v ...your pipelines in order to get more messages from gstreamer. Last, just for checking if it is rather nvv4l2decoder or USB cam issue, can your run both cameras with nvjpegdec (this wouldn’t be a solution for opencv, though): gst-launch-1.0 -v v4l2src device=/dev/video0 ! image/jpeg, width=320, height=240, framerate=15/1, format=MJPG ! nvjpegdec ! 'video/x-raw(memory:NVMM), format=I420' ! nvvidconv ! xvimagesink v4l2src device=/dev/video1 ! image/jpeg, width=320, height=240, framerate=15/1, format=MJPG ! nvjpegdec ! 'video/x-raw(memory:NVMM), format=I420' ! nvvidconv ! xvimagesink

JetPack 4.5 - nvv4l2h264enc no more one instance with opencv 4.5.2 (Segmentation fault)

Robotics & Edge Computing Jetson Systems Jetson Xavier NX

DaneLLL June 21, 2021, 3:57am 21

Hi,
Please apply the prebuilt lib and check if it helps:
Jetson/L4T/r32.5.x patches - eLinux.org
[camera] 3rdparty application fails to open with USB camera

Troubles getting any camera to work

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JetPack 4.5 - nvv4l2h264enc no more one instance with opencv 4.5.2 (Segmentation fault)

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