Python cv2.VideoCapture.read() does not read all frames (Bug #1938)

Added by Dmitry Kit almost 13 years ago. Updated over 9 years ago.

Status:Open Start date:2012-05-15
Priority:Normal Due date:
Assignee:Vadim Pisarevsky % Done:

0%
Category:python bindings
Target version:-
Affected version: Operating System:
Difficulty: HW Platform:
Pull request:

Description

I have some python code that tries to read all the frames from a video file (attached). However, using the following loop:

g_capture = cv2.VideoCapture('fence.wmv')
ret = True
while ret:
   ret,im = g_capture.read()
   cv2.imshow("video", im)
   cv2.waitKey(2)

results in only ~178 or so frames read before ret becomes False and things start failing. However, when I do:
g_capture.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 201)

I correctly get the frame 201. Furthermore the following C code works just fine:

int main(int argc, char* argv[])
{
    CvCapture* capture = cvCaptureFromAVI("fence.wmv");

    IplImage* img = 0; 

    while(true) {
        if(!cvGrabFrame(capture)){              // capture a frame 
            printf("Could not grab a frame\n\7");
            cvWaitKey();
            exit(0);
        }

        img=cvRetrieveFrame(capture);           // retrieve the captured frame

        cvShowImage("mainWin", img); 
        cvWaitKey(20);           // wait 20 ms
    }
    cvReleaseCapture(&capture);
}

I am using the svn version of opencv source code (from about 3 days ago) and I have tried to convert the original video to a supported avi format using the mencoder command found on http://opencv.willowgarage.com/wiki/VideoCodecs .

This bug might be a duplicate of http://code.opencv.org/issues/1690

fence.wmv (1.8 MB) Dmitry Kit, 2012-05-15 06:14 pm

Related issues

related to Bug #1690: VideoCapture is skipping frames Done 2012-03-15

History

#1
Updated by Dmitry Kit almost 13 years ago

Realized I forgot to follow some instructions when I filed this bug:

The opencv build information is included below:

General configuration for OpenCV 2.4.0 =====================================
Version control:                 svn:8335

  Platform:
    Host:                        Windows 6.1 x86
    CMake:                       2.8.8
    CMake generator:             Visual Studio 10
    CMake build tool:            /MICROS~1.0/Common7/IDE/devenv.com
    MSVC:                        1600

  C/C++:
    Built as dynamic libs?:      YES
    C++ Compiler:                cl
    C++ flags (Release):         /DWIN32 /D_WINDOWS /W4  /EHs /GR  /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /arch:SSE /arch:SSE2 /Oi /fp:fast /wd4251 /MP8  /MD /O2 /Ob2 /D NDEBUG   /Zi
    C++ flags (Debug):           /DWIN32 /D_WINDOWS /W4  /EHs /GR  /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D_SCL_SECURE_NO_WARNINGS /Gy /bigobj /arch:SSE /arch:SSE2 /Oi /fp:fast /wd4251 /MP8  /D_DEBUG /MDd /Zi /Ob0 /Od /RTC1
    C Compiler:                  cl
    C flags (Release):           /DWIN32 /D_WINDOWS /W3   /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /arch:SSE /arch:SSE2 /Oi /fp:fast   /MP8  /MD /O2 /Ob2 /D NDEBUG  /Zi
    C flags (Debug):             /DWIN32 /D_WINDOWS /W3   /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /arch:SSE /arch:SSE2 /Oi /fp:fast   /MP8  /D_DEBUG /MDd /Zi  /Ob0 /Od /RTC1
    Linker flags (Release):      /STACK:10000000 /machine:X86   /INCREMENTAL:NO /debug
    Linker flags (Debug):        /STACK:10000000 /machine:X86   /debug /INCREMENTAL

  OpenCV modules:
    To be built:                 calib3d contrib core features2d flann gpu highgui imgproc legacy ml nonfree objdetect photo python stitching ts video videostab

    Disabled by user:            world
    Disabled by dependency:      -
    Unavailable:                 androidcamera java

  GUI:
    QT 4.x:                      YES (ver 4.7.4 EDITION = OpenSource)
    QT OpenGL support:           YES (optimized /x32/qt/lib/QtOpenGL4.lib debug                   /x32/qt/lib/QtOpenGLd4.lib)
    OpenGL support:              YES (glu32 opengl32)

  Media I/O:
    ZLib:                        build (ver 1.2.6)
    JPEG:                        build (ver 62)
    PNG:                         build (ver 1.5.9)
    TIFF:                        build (ver 42)
    JPEG 2000:                   build (ver 1.900.1)
    OpenEXR:                     NO
    OpenNI:                      NO
    OpenNI PrimeSensor Modules:  NO
    XIMEA:                       NO

  Video I/O:                     DirectShow
    FFMPEG:                      YES (prebuilt binaries)
      codec:                     YES (ver 53.61.100)
      format:                    YES (ver 53.32.100)
      util:                      YES (ver 51.35.100)
      swscale:                   YES (ver 2.1.100)
      gentoo-style:              YES

  Other third-party libraries:
    Use IPP:                     NO
    Use TBB:                     YES (ver 4.0 interface 6004)
    Use Cuda:                    YES (ver 4.2)
    Use Eigen:                   NO
    Use Clp:                     NO

  NVIDIA CUDA:                   (ver 4.2)
    Use CUFFT:                   YES
    Use CUBLAS:                  YES
    NVIDIA GPU arch:             11 12 13 20 21 30
    NVIDIA PTX archs:            11 12 13 20 21 30
    NVIDIA GPU features:         11 12 13 20 20 30 20

  Python:
    Interpreter:                /Python27/python.exe (ver 2.7.2)
    Libraries:                   /Python27/libs/python27.lib (ver 2.7.2)
    numpy:                       /Python27/lib/site-packages/numpy/core/include (ver 1.6.1)
    packages path:               /Python27/Lib/site-packages

  Documentation:
    Build Documentation:         NO
    Sphinx:                      NO
    PdfLaTeX compiler:           /MiKTeX 2.9/miktex/bin/x64/pdflatex.exe

  Tests and samples:
    Tests:                       YES
    Performance tests:           YES
    Examples:                    NO

  Install path:                  /opencv_new/trunk/opencv/build32/install

  cvconfig.h is in:            /opencv_new/trunk/opencv/build32
-----------------------------------------------------------------

#2
Updated by Maksim Shabunin over 9 years ago

Issue has been transferred to GitHub: https://github.com/Itseez/opencv/issues/4362

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