Can I use x264 with Opencv in Python on Linux

0
votes

I am using python 3.6 and opencv 3.4.1 to capture video from a Logitech C920 webcam. I am used to Windows, where I would write my own DirectShow filters to get access to frames and control the camera. I am finding myself out of my depth on Linux.

I know it can run 24fps at least by using GTK UVC video viewer, but I'm only getting 5fps. I suspect that this is due to the format - to get higher rates I need something like x264. It may be that this is impossible for opencv because it means that it can no longer grab a single frame.

I have tried setting the video codec, but I am told that

cap.set(cv2.CAP_PROP_FORMAT, cv2.VideoWriter_fourcc(...

VIDEOIO ERROR: V4L2: setting property #8 is not supported

Other people have asked similar questions, but I haven't been able to see a convincing answer:

(no answer) Capturing H264 stream with OpenCV

(blames drivers) http://answers.opencv.org/question/30185/frame-capture-is-needlessly-slow/

(sets camera format in c++) OpenCV VideoCapture with H264 CODEC

(also done in c++ and OpenCV 2.4) Capturing 1080p at 30fps from logitech c920 with openCV 2.4.3

I found a link claiming that x264 etc doesn't support frame grabbing, therefore it can't be done, but now I can't find it - this would seem to be contradicted by the answers in c++ and the fact that we can work with x264 file formats.

Any clarity would be appreciated.

EDIT:

As requested, here are the outputs of cv2.getBuildInformation():

General configuration for OpenCV 3.4.1 =====================================
  Version control:               3.4.1

  Platform:
    Timestamp:                   2018-05-19T13:51:11Z
    Host:                        Linux 4.4.0-101-generic x86_64
    CMake:                       3.9.0
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/gmake
    Configuration:               Release

  CPU/HW features:
    Baseline:                    SSE SSE2 SSE3
      requested:                 SSE3
    Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2
      requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
      SSE4_1 (3 files):          + SSSE3 SSE4_1
      SSE4_2 (1 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
      FP16 (1 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
      AVX (5 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
      AVX2 (9 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2

  C/C++:
    Built as dynamic libs?:      NO
    C++ Compiler:                /opt/rh/devtoolset-2/root/usr/bin/c++  (ver 4.8.2)
    C++ flags (Release):         -Wl,-strip-all   -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 -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -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):           -Wl,-strip-all   -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 -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -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-2/root/usr/bin/cc
    C flags (Release):           -Wl,-strip-all   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -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):             -Wl,-strip-all   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -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):      -L/root/ffmpeg_build/lib
    Linker flags (Debug):        -L/root/ffmpeg_build/lib
    ccache:                      NO
    Precompiled headers:         NO
    Extra dependencies:          /opt/Qt4.8.7/lib/libQtGui.so /opt/Qt4.8.7/lib/libQtTest.so /opt/Qt4.8.7/lib/libQtCore.so /lib64/libz.so /opt/libjpeg-turbo/lib64/libjpeg.a avcodec avformat avutil swscale dl m pthread rt
    3rdparty dependencies:       ittnotify libprotobuf libwebp libpng libtiff libjasper IlmImf

  OpenCV modules:
    To be built:                 calib3d core dnn features2d flann highgui imgcodecs imgproc java_bindings_generator ml objdetect photo python3 python_bindings_generator shape stitching superres video videoio videostab
    Disabled:                    js world
    Disabled by dependency:      -
    Unavailable:                 cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev java python2ts viz
    Applications:                -
    Documentation:               NO
    Non-free algorithms:         NO

  GUI:
    QT:                          YES (ver 4.8.7 EDITION = OpenSource)
      QT OpenGL support:         NO
    GTK+:                        NO
    VTK support:                 NO

  Media I/O:
    ZLib:                        /lib64/libz.so (ver 1.2.3)
    JPEG:                        /opt/libjpeg-turbo/lib64/libjpeg.a (ver )
    WEBP:                        build (ver encoder: 0x020e)
    PNG:                         build (ver 1.6.34)
    TIFF:                        build (ver 42 - 4.0.9)
    JPEG 2000:                   build (ver 1.900.1)
    OpenEXR:                     build (ver 1.7.1)

  Video I/O:
    DC1394:                      NO
    FFMPEG:                      YES
      avcodec:                   YES (ver 58.19.100)
      avformat:                  YES (ver 58.13.100)
      avutil:                    YES (ver 56.18.100)
      swscale:                   YES (ver 5.2.100)
      avresample:                NO
    GStreamer:                   NO
    libv4l/libv4l2:              NO
    v4l/v4l2:                    linux/videodev.h linux/videodev2.h
    gPhoto2:                     NO

  Parallel framework:            pthreads

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    Lapack:                      NO
    Eigen:                       NO
    Custom HAL:                  NO
    Protobuf:                    build (3.5.1)

  NVIDIA CUDA:                   NO

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

  Python 3:
    Interpreter:                 /opt/python/cp36-cp36m/bin/python (ver 3.6.5)
    Libraries:                   libpython3.6m.a (ver 3.6.5)
    numpy:                       /opt/python/cp36-cp36m/lib/python3.6/site-packages/numpy/core/include (ver 1.11.3)
    packages path:               lib/python3.6/site-packages

  Python (for build):            /opt/python/cp36-cp36m/bin/python

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

  Matlab:                        NO

  Install to:                    /io/_skbuild/cmake-install
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1
python-3.xopencvcomputer-vision
Sorry, I probably didn't make it clear enough - I'm only getting 5fps. It's too slow for my needs. That's the problem I'm trying to solve - but from what I can see, the problem is the format. If I'm wrong then please, tell me :) – mike1952
Try using FFmpeg to list pixel formats and encode with different frame rates and supported pixel formats. – zindarod
I've done as you asked - H.264 is supported. But, as I said, when I try to set the format to H264, I'm told that opencv doesn't support setting camera formats. – mike1952
Sorry, now I understand - actually play around in ffmpeg. On it now. – mike1952
stackoverflow.com/questions/50470593/… I suspect that this might be part of the problem. Also, ffmpeg has a problem with resetting formats. I hate video :) – mike1952

1 Answers

0
votes

So as zindarod correctly pointed out, the solution is to:

  • run cv2.getBuildInformation()
  • Check if libv4l/libv4l2 has NO/NO as the value (if it doesn't you have some other problem)
  • Compile OpenCV from source.

Compiling OpenCV is tricky, but manageable, even for someone like me who was raised on Windows.

https://docs.opencv.org/3.2.0/d7/d9f/tutorial_linux_install.html https://docs.opencv.org/3.0-beta/doc/tutorials/introduction/linux_eclipse/linux_eclipse.html

Although those are a little out of date. In eclipse you'll need references to opencv_videoio opencv_core opencv_highgui opencv_videoio

#include "opencv2/opencv.hpp"
#include "opencv2/videoio.hpp"
using namespace cv;

int main(int, char**)
{
    VideoCapture cap(0); // open the default camera
    if(!cap.isOpened())  // check if we succeeded
        return -1;

    cap.set(CV_CAP_PROP_FRAME_WIDTH,1920);
    cap.set(CV_CAP_PROP_FRAME_HEIGHT,1080);
    Mat edges;
    namedWindow("camera",1);
    for(;;)
    {
        Mat frame;
        cap >> frame; // get a new frame from camera
        imshow("camera", frame);
        if(waitKey(30) >= 0) break;
    }
    return 0;
}