How to use VideoCapture?

[cbrautigam2]

I want to use the VideoCapture class from this example: https://docs.opencv.org/4.7.0/d4/dee/tutorial_optical_flow.html. When I run the following code:

String filename = "/path/to/a/local.mp4";
VideoCapture capture = new VideoCapture(filename);
BytePointer buildInformation = opencv_core.getBuildInformation();
System.out.println("buildInfo:" + buildInformation.getString(Charset.defaultCharset()));
if (!capture.isOpened()) {
    // error in opening the video input
    System.out.println("Unable to open file!");
    System.exit(-1);
}

I always get capture.isOpened() returning false. Yes, the path is correct, yes the file is readable, etc. I enabled debug and I get this clue:

[ WARN:[email protected]] global cap.cpp:130 open VIDEOIO(FFMPEG): trying capture filename='/data/extractions/data/fmv/66aa6c65dcafdb7cfac948cc.mp4' ...
[ WARN:[email protected]] global cap.cpp:190 open VIDEOIO(FFMPEG): backend is not available (plugin is missing, or can't be loaded due dependencies or it is not compatible)
[ WARN:[email protected]] global cap.cpp:130 open VIDEOIO(GSTREAMER): trying capture filename='/data/extractions/data/fmv/66aa6c65dcafdb7cfac948cc.mp4' ...
[ WARN:[email protected]] global cap.cpp:190 open VIDEOIO(GSTREAMER): backend is not available (plugin is missing, or can't be loaded due dependencies or it is not compatible)
[ WARN:[email protected]] global cap.cpp:130 open VIDEOIO(INTEL_MFX): trying capture filename='/data/extractions/data/fmv/66aa6c65dcafdb7cfac948cc.mp4' ...
[ WARN:[email protected]] global cap.cpp:190 open VIDEOIO(INTEL_MFX): backend is not available (plugin is missing, or can't be loaded due dependencies or it is not compatible)
[ WARN:[email protected]] global cap.cpp:130 open VIDEOIO(V4L2): trying capture filename='/data/extractions/data/fmv/66aa6c65dcafdb7cfac948cc.mp4' ...
[ WARN:[email protected]] global cap.cpp:153 open VIDEOIO(V4L2): can't create capture
[ WARN:[email protected]] global cap.cpp:130 open VIDEOIO(CV_IMAGES): trying capture filename='/data/extractions/data/fmv/66aa6c65dcafdb7cfac948cc.mp4' ...
[ WARN:[email protected]] global cap.cpp:142 open VIDEOIO(CV_IMAGES): created, isOpened=0
[ WARN:[email protected]] global cap.cpp:130 open VIDEOIO(CV_MJPEG): trying capture filename='/data/extractions/data/fmv/66aa6c65dcafdb7cfac948cc.mp4' ...
[ WARN:[email protected]] global cap.cpp:153 open VIDEOIO(CV_MJPEG): can't create capture
Debug: Registering org.bytedeco.opencv.opencv_videoio.VideoCapture[address=0x7f6375402430,position=0,limit=1,capacity=1,deallocator=org.bytedeco.javacpp.Pointer$NativeDeallocator[ownerAddress=0x7f6375402430,deallocatorAddress=0x7f633803a310]]

So it would appear VideoCapture can not find an implementation to open the mp4 file, and further from the build information it confirms that ffmpeg is not part of the opencv build that I'm using. I would expect to see and FFMPEG entry under the Video I/O: section. Only v4l/v4l2 is listed:

buildInfo:
General configuration for OpenCV 4.7.0 =====================================
  Version control:               ab435e3

  Extra modules:
    Location (extra):            /__w/javacpp-presets/javacpp-presets/opencv/cppbuild/linux-x86_64/opencv_contrib-4.7.0/modules
    Version control (extra):     ab435e3

  Platform:
    Timestamp:                   2023-06-03T00:03:53Z
    Host:                        Linux 5.15.0-1038-azure x86_64
    CMake:                       3.24.2
    CMake generator:             Unix Makefiles
    CMake build tool:            /opt/rh/devtoolset-9/root/usr/bin/gmake
    Configuration:               Release

  CPU/HW features:
    Baseline:                    SSE SSE2 SSE3
      requested:                 SSE3
    Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2 AVX512_SKX
      requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
      SSE4_1 (14 files):         + SSSE3 SSE4_1
      SSE4_2 (1 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
      FP16 (0 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
      AVX (4 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
      AVX2 (30 files):           + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2
      AVX512_SKX (5 files):      + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2 AVX_512F AVX512_COMMON AVX512_SKX

  C/C++:
    Built as dynamic libs?:      YES
    C++ standard:                11
    C++ Compiler:                /opt/rh/devtoolset-9/root/usr/bin/g++  -std=c++11 -m64 (ver 9.3.1)
    C++ flags (Release):         -w   -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -w   -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    C Compiler:                  /opt/rh/devtoolset-9/root/usr/bin/gcc  -m64
    C flags (Release):           -fsigned-char -W -Wall -Wreturn-type -Waddress -Wsequence-point -Wformat -Wformat-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 -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -fsigned-char -W -Wall -Wreturn-type -Waddress -Wsequence-point -Wformat -Wformat-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 -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
    Linker flags (Release):      -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
    Linker flags (Debug):        -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
    ccache:                      YES
    Precompiled headers:         NO
    Extra dependencies:          dl m pthread rt
    3rdparty dependencies:

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

  GUI:                           GTK2
    GTK+:                        YES (ver 2.24.31)
      GThread :                  YES (ver 2.56.1)
      GtkGlExt:                  NO
    VTK support:                 NO

  Media I/O: 
    ZLib:                        build (ver 1.2.13)
    JPEG:                        build-libjpeg-turbo (ver 2.1.3-62)
      SIMD Support Request:      NO
    WEBP:                        build (ver encoder: 0x020f)
    PNG:                         build (ver 1.6.37)
    TIFF:                        build (ver 42 - 4.2.0)
    JPEG 2000:                   build Jasper (ver 1.900.1)
    OpenEXR:                     build (ver 2.3.0)
    HDR:                         YES
    SUNRASTER:                   YES
    PXM:                         YES
    PFM:                         YES

  Video I/O:
    v4l/v4l2:                    YES (linux/videodev2.h)

  Parallel framework:            pthreads

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    Lapack:                      YES (/root/.javacpp/cache/openblas-0.3.23-1.5.9-linux-x86_64.jar/org/bytedeco/openblas/linux-x86_64/libopenblas.so)
    Custom HAL:                  NO
    Protobuf:                    build (3.19.1)

  OpenCL:                        YES (no extra features)
    Include path:                /__w/javacpp-presets/javacpp-presets/opencv/cppbuild/linux-x86_64/opencv-4.7.0/3rdparty/include/opencl/1.2
    Link libraries:              Dynamic load

  Python 3:
    Interpreter:                 /root/.javacpp/cache/cpython-3.11.3-1.5.9-linux-x86_64.jar/org/bytedeco/cpython/linux-x86_64/bin/python3.11 (ver 3.11)
    Libraries:                   /root/.javacpp/cache/cpython-3.11.3-1.5.9-linux-x86_64.jar/org/bytedeco/cpython/linux-x86_64/lib/python3.11/ (ver 3.11.3)
    numpy:                       /root/.javacpp/cache/numpy-1.24.3-1.5.9-linux-x86_64.jar/org/bytedeco/numpy/linux-x86_64/python/numpy/core/include (ver )
    install path:                /__w/javacpp-presets/javacpp-presets/opencv/cppbuild/linux-x86_64/lib/python3.11/site-packages

  Python (for build):            /usr/bin/python2

  Java:                          
    ant:                         /bin/ant (ver 1.9.4)
    JNI:                         /usr/lib/jvm/java/include /usr/lib/jvm/java/include/linux /usr/lib/jvm/java/include
    Java wrappers:               YES
    Java tests:                  NO

  Install to:                    /__w/javacpp-presets/javacpp-presets/opencv/cppbuild/linux-x86_64
-----------------------------------------------------------------

I have the following dependencies in my maven build, but ffmpeg seems to not be available:

<dependency>
    <groupId>org.bytedeco</groupId>
    <artifactId>javacv-platform</artifactId>
    <version>1.5.9</version>
</dependency>
<dependency>
    <groupId>org.bytedeco</groupId>
    <artifactId>ffmpeg-platform-gpl</artifactId>
    <version>6.0-1.5.9</version>
</dependency>
<dependency>
    <groupId>org.bytedeco</groupId>
    <artifactId>ffmpeg-platform</artifactId>
    <version>6.0-1.5.9</version>
</dependency>

Ultimately I just want to be able to open, read and capture frames from video files. What am I missing here?

[saudet]

The binaries aren't linked with FFmpeg. Please use FFmpegFrameGrabber insteead.

[cbrautigam2]

ok thanks for the tip