Slow camera capture on Raspberry Pi 400

Question

Using Ubuntu 64 bit on a Raspberry Pi 400 I get a very slow frame rate, like 2.2 frames per second.

int main() {
    cv::VideoCapture cap(0);
    do {
        double t = (double)cv::getTickCount();
        std::cout << "Tick count: " << cv::getTickCount() << std::endl;         
        cap >> img;
        key = cv::waitKey(1);
        t = ((double)cv::getTickCount() - t)/cv::getTickFrequency();
        std::cout<< " Frequency: " << cv::getTickFrequency() << std::endl;
        std::cout<< "Tick: " << t << std::endl;
        std::cout<< "Rate: " << (1.0 / t)<< std::endl;
    } while(key != 27);
    return 0;
}

As you can see, I'm not even displaying the image on screen or doing any image operation.

The same camera has a better performance when used by other apps (like cheese). Are there mechanisms for achieving a better performance?

UPDATE: here you have my build info

General configuration for OpenCV 4.2.0 ===================================== Version control: unknown

Extra modules: Location (extra): /build/opencv-f6XtMJ/opencv-4.2.0+dfsg/contrib/modules Version control (extra): unknown

Platform: Timestamp: 2020-10-04T07:09:34Z Host: Linux 4.15.0-118-generic aarch64 CMake: 3.16.3 CMake generator: Ninja CMake build tool: /usr/bin/ninja Configuration: Release

CPU/HW features: Baseline: NEON FP16 required: NEON disabled: VFPV3

C/C++: Built as dynamic libs?: YES C++ Compiler: /usr/bin/c++ (ver 10.2.0) C++ flags (Release): -g -O2 -fdebug-prefix-map=/build/opencv-f6XtMJ/opencv-4.2.0+dfsg=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -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 -Wsign-promo -Wuninitialized -Winit-self -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 -O2 -fdebug-prefix-map=/build/opencv-f6XtMJ/opencv-4.2.0+dfsg=. -fstack-protector-strong -Wformat -Werror=format-security -DNDEBUG C++ flags (Debug): -g -O2 -fdebug-prefix-map=/build/opencv-f6XtMJ/opencv-4.2.0+dfsg=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -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 -Wsign-promo -Wuninitialized -Winit-self -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 -DDEBUG -D_DEBUG C Compiler: /usr/bin/cc C flags (Release): -g -O2 -fdebug-prefix-map=/build/opencv-f6XtMJ/opencv-4.2.0+dfsg=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -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 -Wsign-promo -Wuninitialized -Winit-self -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 -O2 -fdebug-prefix-map=/build/opencv-f6XtMJ/opencv-4.2.0+dfsg=. -fstack-protector-strong -Wformat -Werror=format-security -DNDEBUG C flags (Debug): -g -O2 -fdebug-prefix-map=/build/opencv-f6XtMJ/opencv-4.2.0+dfsg=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -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 -Wsign-promo -Wuninitialized -Winit-self -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 -DDEBUG -D_DEBUG Linker flags (Release): -Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -Wl,--gc-sections -Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now Linker flags (Debug): -Wl,-Bsymbolic-functions -Wl,-z,relro -Wl,-z,now -Wl,--gc-sections
ccache: NO Precompiled headers: NO Extra dependencies: dl m pthread rt 3rdparty dependencies:

OpenCV modules: To be built: aruco bgsegm bioinspired calib3d ccalib core datasets dnn dnn_objdetect dnn_superres dpm face features2d flann freetype fuzzy hdf hfs highgui img_hash imgcodecs imgproc java line_descriptor ml objdetect optflow phase_unwrapping photo plot python3 quality reg rgbd saliency shape stereo stitching structured_light superres surface_matching text tracking video videoio videostab viz ximgproc xobjdetect xphoto Disabled: world Disabled by dependency: sfm Unavailable: cnn_3dobj cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev cvv gapi js matlab ovis python2 ts Applications: apps Documentation: doxygen python javadoc Non-free algorithms: NO

GUI: GTK+: YES (ver 3.24.23) GThread : YES (ver 2.66.0) GtkGlExt: NO OpenGL support: NO VTK support: YES (ver 6.3.0)

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: /usr/lib/aarch64-linux-gnu/libwebp.so (ver encoder: 0x020e) PNG: /usr/lib/aarch64-linux-gnu/libpng.so (ver 1.6.37) TIFF: /usr/lib/aarch64-linux-gnu/libtiff.so (ver 42 / 4.1.0) OpenEXR: /usr/lib/aarch64-linux-gnu/libImath.so /usr/lib/aarch64-linux-gnu/libIlmImf.so /usr/lib/aarch64-linux-gnu/libIex.so /usr/lib/aarch64-linux-gnu/libHalf.so /usr/lib/aarch64-linux-gnu/libIlmThread.so (ver 2.5.3) GDAL: YES (/usr/lib/libgdal.so) GDCM: YES (3.0.7) HDR: YES SUNRASTER: YES PXM: YES PFM: YES

Video I/O: DC1394: YES (2.2.6) FFMPEG: YES avcodec: YES (58.91.100) avformat: YES (58.45.100) avutil: YES (56.51.100) swscale: YES (5.7.100) avresample: YES (4.0.0) GStreamer: YES (1.18.0) PvAPI: NO v4l/v4l2: YES (linux/videodev2.h)

Parallel framework: TBB (ver 2020.3 interface 11103)

Trace: YES (built-in)

Other third-party libraries: Lapack: NO Eigen: YES (ver 3.3.7) Custom HAL: NO Protobuf: /usr/lib/aarch64-linux-gnu/libprotobuf.so (3.12.3)

OpenCL: YES (no extra features) Include path: /usr/include/CL Link libraries: Dynamic load

Python 3: Interpreter: /usr/bin/python3 (ver 3.8.6) Libraries: /usr/lib/aarch64-linux-gnu/libpython3.8.so (ver 3.8.6) numpy: /usr/lib/python3/dist-packages/numpy/core/include (ver 1.18.4) install path: lib/python3.8/dist-packages

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

Java:
ant: /usr/bin/ant (ver 1.10.8) JNI: /usr/lib/jvm/default-java/include /usr/lib/jvm/default-java/include/linux /usr/lib/jvm/default-java/include Java wrappers: YES Java tests: NO

Install to: /usr

If you put back the headers you have removed, other folks might run your code. If you add cv::getBuildInformation(); output, someone may spot an issue. If you show your compilation command with parameters, an issue may become apparent. — Mark Setchell
– Mark Setchell, Commented Apr 14, 2021 at 7:38
Might be worth changing waitKey to pollKey, waitKey will wait for at least a millisecond, it could be more. cout can be slow std::endl makes it even slower — Alan Birtles
– Alan Birtles, Commented Apr 14, 2021 at 7:41
@AlanBirtles it is not cout or endl fault. I've already tried without them and the performance was the same. — Hola Soy Edu Feliz Navidad
– Hola Soy Edu Feliz Navidad, Commented Apr 14, 2021 at 12:13
have you tried changing/removing waitKey? are you using compiler optimisations? — Alan Birtles
– Alan Birtles, Commented Apr 14, 2021 at 12:45

Hola Soy Edu Feliz Navidad · Accepted Answer · 2021-04-17 01:33:31Z

1

I think that I found the issue. listing the camera resolutions I could see that there was a setting with only 2 fps, and it was when using YUYV format. I forced the input to be MJPG with cap.set(cv::CAP_PROP_FOURCC ,cv::VideoWriter::fourcc('M', 'J', 'P', 'G') ); and the frame rate increased to 19-20, which is still low but might be acceptable.

answered Apr 17, 2021 at 1:33

Hola Soy Edu Feliz Navidad

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