Can I use x264 with Opencv in Python on Linux - python-3.x

Question

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
-----------------------------------------------------------------

Answer 1

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;
}