Cannot read camera stream by using OpenCV Python on Jetson Nano

Here is my opencv information:

nvidia@nvdia-desktop:~$ python3
Python 3.6.9 (default, Jun 29 2022, 11:45:57)
[GCC 8.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> print(cv2.getBuildInformation())

General configuration for OpenCV 4.5.3 =====================================
  Version control:               unknown

  Extra modules:
    Location (extra):            /home/nvdia/opencv_contrib-4.5.3/modules
    Version control (extra):     unknown

  Platform:
    Timestamp:                   2022-08-01T07:08:50Z
    Host:                        Linux 4.9.253-tegra aarch64
    CMake:                       3.10.2
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/make
    Configuration:               RELEASE

  CPU/HW features:
    Baseline:                    NEON FP16

  C/C++:
    Built as dynamic libs?:      YES
    C++ standard:                11
    C++ Compiler:                /usr/bin/c++  (ver 7.5.0)
    C++ flags (Release):         -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    C Compiler:                  /usr/bin/cc
    C flags (Release):           -fsigned-char -W -Wall -Werror=return-type -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -fsigned-char -W -Wall -Werror=return-type -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections    -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
    Linker flags (Release):      -Wl,--gc-sections -Wl,--as-needed
    Linker flags (Debug):        -Wl,--gc-sections -Wl,--as-needed
    ccache:                      NO
    Precompiled headers:         NO
    Extra dependencies:          dl m pthread rt
    3rdparty dependencies:

  OpenCV modules:
    To be built:                 alphamat aruco barcode bgsegm bioinspired calib3d ccalib core datasets dnn dnn_objdetect dnn_superres dpm face features2d flann fuzzy gapi hfs highgui img_hash imgcodecs imgproc intensity_transform line_descriptor mcc ml objdetect optflow phase_unwrapping photo plot python3 quality rapid reg rgbd saliency shape stereo stitching structured_light superres surface_matching text tracking video videoio videostab wechat_qrcode ximgproc xobjdetect xphoto
    Disabled:                    world xfeatures2d
    Disabled by dependency:      -
    Unavailable:                 cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev cvv freetype hdf java julia matlab ovis python2 sfm ts viz
    Applications:                apps
    Documentation:               NO
    Non-free algorithms:         NO

  GUI:
    GTK+:                        NO
    OpenGL support:              NO
    VTK support:                 NO

  Media I/O:
    ZLib:                        /usr/lib/aarch64-linux-gnu/libz.so (ver 1.2.11)
    JPEG:                        /usr/lib/aarch64-linux-gnu/libjpeg.so (ver 80)
    WEBP:                        build (ver encoder: 0x020f)
    PNG:                         /usr/lib/aarch64-linux-gnu/libpng.so (ver 1.6.34)
    TIFF:                        build (ver 42 - 4.2.0)
    JPEG 2000:                   OpenJPEG (ver 2.3.0)
    OpenEXR:                     build (ver 2.3.0)
    HDR:                         YES
    SUNRASTER:                   YES
    PXM:                         YES
    PFM:                         YES

  Video I/O:
    DC1394:                      NO
    FFMPEG:                      YES
      avcodec:                   YES (57.107.100)
      avformat:                  YES (57.83.100)
      avutil:                    YES (55.78.100)
      swscale:                   YES (4.8.100)
      avresample:                NO
    GStreamer:                   YES (1.14.5)
    v4l/v4l2:                    YES (linux/videodev2.h)

  Parallel framework:            TBB (ver 2017.0 interface 9107)

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    Lapack:                      NO
    Eigen:                       YES (ver 3.3.4)
    Custom HAL:                  YES (carotene (ver 0.0.1))
    Protobuf:                    build (3.5.1)

  OpenCL:                        YES (no extra features)
    Include path:                /home/nvdia/opencv-4.5.3/3rdparty/include/opencl/1.2
    Link libraries:              Dynamic load

  Python 3:
    Interpreter:                 /usr/bin/python3 (ver 3.6.9)
    Libraries:                   /usr/lib/aarch64-linux-gnu/libpython3.6m.so (ver 3.6.9)
    numpy:                       /usr/local/lib/python3.6/dist-packages/numpy/core/include (ver 1.19.5)
    install path:                lib/python3.6/dist-packages/cv2/python-3.6

  Python (for build):            /usr/bin/python3

  Java:
    ant:                         NO
    JNI:                         NO
    Java wrappers:               NO
    Java tests:                  NO

  Install to:                    /usr
-----------------------------------------------------------------

System Information:

nvidia@nvdia-desktop:~$ uname -a
Linux nvdia-desktop 4.9.253-tegra #1 SMP PREEMPT Sat Feb 19 08:59:22 PST 2022 aarch64 aarch64 aarch64 GNU/Linux

I can see the live video stream from my RPi Camera 2 by using the following command:

gst-launch-1.0 nvarguscamerasrc sensor_id=0 ! \
   'video/x-raw(memory:NVMM),width=1920, height=1080, framerate=30/1' ! \
   nvvidconv flip-method=0 ! 'video/x-raw,width=960, height=540' ! \
   nvvidconv ! nvegltransform ! nveglglessink -e

But cannot read from opencv:

nvidia@nvdia-desktop:~/video-processor-software$ python3
Python 3.6.9 (default, Jun 29 2022, 11:45:57)
[GCC 8.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cap = cv2.VideoCapture('nvarguscamerasrc sensor-id=0 !video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080, framerate=(fraction)30/1 ! nvvidconv flip-method=0 ! video/x-raw, width=(int)960, height=(int)540, format=(string)BGRx ! videoconvert ! video/x-raw, format=(string)BGR ! appsink')
GST_ARGUS: Creating output stream
CONSUMER: Waiting until producer is connected...
GST_ARGUS: Available Sensor modes :
GST_ARGUS: 3264 x 2464 FR = 21.000000 fps Duration = 47619048 ; Analog Gain range min 1.000000, max 10.625000; Exposure Range min 13000, max 683709000;

GST_ARGUS: 3264 x 1848 FR = 28.000001 fps Duration = 35714284 ; Analog Gain range min 1.000000, max 10.625000; Exposure Range min 13000, max 683709000;

GST_ARGUS: 1920 x 1080 FR = 29.999999 fps Duration = 33333334 ; Analog Gain range min 1.000000, max 10.625000; Exposure Range min 13000, max 683709000;

GST_ARGUS: 1640 x 1232 FR = 29.999999 fps Duration = 33333334 ; Analog Gain range min 1.000000, max 10.625000; Exposure Range min 13000, max 683709000;

GST_ARGUS: 1280 x 720 FR = 59.999999 fps Duration = 16666667 ; Analog Gain range min 1.000000, max 10.625000; Exposure Range min 13000, max 683709000;

GST_ARGUS: 1280 x 720 FR = 120.000005 fps Duration = 8333333 ; Analog Gain range min 1.000000, max 10.625000; Exposure Range min 13000, max 683709000;

GST_ARGUS: Running with following settings:
   Camera index = 0
   Camera mode  = 2
   Output Stream W = 1920 H = 1080
   seconds to Run    = 0
   Frame Rate = 29.999999
GST_ARGUS: Setup Complete, Starting captures for 0 seconds
GST_ARGUS: Starting repeat capture requests.
CONSUMER: Producer has connected; continuing.
[ WARN:0] global /home/nvdia/opencv-4.5.3/modules/videoio/src/cap_gstreamer.cpp (1081) open OpenCV | GStreamer warning: Cannot query video position: status=0, value=-1, duration=-1
>>>

Am I missing something?
Thanks!

Sorry for the late response, is this still an issue to support? Thanks

Hi, @kayccc

It was a silly typo! :)

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