Got an error when tried to capture from Usb Camera
My set up:
Python 3.6
Windows10
Opencv 3.4.1
My test code:
cap = cv2.VideoCapture(0)
while True:
ret, image = cap.read()
if not ret:
break
cv2.imshow("test", image)
cv2.waitKey(1)
When I run this code, It can only capture the first frame from the camera, but the frame is black. It can not capture from the second frame. This code worked perfectly if I use a video file instead.
print(cv2.getBuildInformation()) give this result:
General configuration for OpenCV 3.4.1 =====================================
Version control: 3.4.1
Platform:
Timestamp: 2018-05-19T15:09:33Z
Host: Windows 6.3.9600 AMD64
CMake: 3.11.1
CMake generator: Visual Studio 14 2015 Win64
CMake build tool: C:/Program Files (x86)/MSBuild/14.0/bin/MSBuild.exe
MSVC: 1900
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++11: YES
C++ Compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe (ver 19.0.24215.1)
C++ flags (Release): /DWIN32 /D_WINDOWS /W4 /GR /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi /EHa /wd4127 /wd4251 /wd4324 /wd4275 /wd4512 /wd4589 /MP2 /MT /O2 /Ob2 /DNDEBUG
C++ flags (Debug): /DWIN32 /D_WINDOWS /W4 /GR /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi /EHa /wd4127 /wd4251 /wd4324 /wd4275 /wd4512 /wd4589 /MP2 /MTd /Zi /Ob0 /Od /RTC1
C Compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe
C flags (Release): /DWIN32 /D_WINDOWS /W3 /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi /MP2 /MT /O2 /Ob2 /DNDEBUG
C flags (Debug): /DWIN32 /D_WINDOWS /W3 /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi /MP2 /MTd /Zi /Ob0 /Od /RTC1
Linker flags (Release): /machine:x64 /NODEFAULTLIB:atlthunk.lib /INCREMENTAL:NO /NODEFAULTLIB:libcmtd.lib /NODEFAULTLIB:libcpmtd.lib /NODEFAULTLIB:msvcrtd.lib
Linker flags (Debug): /machine:x64 /NODEFAULTLIB:atlthunk.lib /debug /INCREMENTAL /NODEFAULTLIB:libcmt.lib /NODEFAULTLIB:libcpmt.lib /NODEFAULTLIB:msvcrt.lib
ccache: NO
Precompiled headers: YES
Extra dependencies: comctl32 gdi32 ole32 setupapi ws2_32 vfw32
3rdparty dependencies: ittnotify libprotobuf zlib libjpeg libwebp libpng libtiff libjasper IlmImf ippiw ippicv
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 python2 ts viz
Applications: -
Documentation: NO
Non-free algorithms: NO
Windows RT support: NO
GUI:
Win32 UI: YES
VTK support: NO
Media I/O:
ZLib: build (ver 1.2.11)
JPEG: build (ver 90)
WEBP: build (ver encoder: 0x020e)
PNG: build (ver 1.6.34)
TIFF: build (ver 42 - 4.0.9)
JPEG 2000 ...
how did you install this ? (opencv does not have version numbers like that)
try a :
print(cv2.getBuildInformation())
there is a "VideoIO" section, please report back.are you able to use your webcam with other programs (like vlc, mediaplayer, etc) ?
Hi berak, I edited the question, I updated the result of print(cv2.getBuildInformation()) above. I tried the above code many times and It rarely works. I tried it for about 10 times and it only works 1 time. I don't know what is the problem I use this site to test my webcam: https://webcamera.io/vi/ and it worked correctly
change a webcam to see if the problem still happen.
But, Why sometime it works, sometime it not works. I tried 3 webcams and it gave the same result.
strange,how many cameras did you use at a time?
I used 1 or 2 cameras at a time, But I changed the ID of camera in code. Now, After I restarted my computer, 1 camera works, and the others are not.