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• Child Process will neither complete nor abort in Windows ?

  4 septembre 2014, par Karthikeya Vaidya

  How to make my java parent process wait till child process gets completed. I have tried with runtime.exec and with processBuilder.pb :

  String cmd = "ffmpeg -i input.vob output.mp4" 
  
  Runtime rt = Runtime.getRuntime();
  
  Process proc = rt.exec(cmd); 
  
  proc.waitFor();

  ---

  This works fine with small input file (say less than 10 Mb). If I give larger input file then program will be hanged. Output file will be partially created and file creation will be hanged and control will not return. Even proc.join(10000); did not give any useful result. Here parent process is terminating before child process (ffmpeg) gets completed.

  How to overcome this problem ?

• OpenCV cv2 not working in Windows 7

  6 septembre 2014, par Subhendu Sinha Chaudhuri

  I have a Windows 7 SP1 64 Bit machine with open cv2.4.9 installed and python 2.7.6 installed.
  I use pre compiled version of opencv

  The following code works perfectly for me

  import cv2.cv as cv
  
  import time
  
  
  
  cv.NamedWindow("camera", 0)
  
  
  
  capture = cv.CaptureFromCAM(0)
  
  
  
  while True:
  
      img = cv.QueryFrame(capture)
  
      cv.ShowImage("camera", img)
  
      if cv.WaitKey(10) == 27:
  
          break
  
  cv.DestroyAllWindows()

  Now when I try to use this code

  import cv2
  
  import numpy as np
  
  cam = cv2.VideoCapture(0)
  
  s, img = cam.read()
  
  
  
  winName = "Movement Indicator"
  
  cv2.namedWindow(winName, cv2.CV_WINDOW_AUTOSIZE)
  
  
  
  while s:
  
    cv2.imshow( winName,img )
  
  
  
    s, img = cam.read()
  
  
  
    key = cv2.waitKey(10)
  
    if key == 27:
  
      cv2.destroyWindow(winName)
  
      break
  
  
  
  print "Goodbye"

  The window is opened , the camera is initialized (as camera lights are on) , but nothing is displayed and the window closes and the program exits.

  WHERE am I going wrong ??

  QUESTION 2
  Can any one also suggest me how to capture live video stream from my Linux machine 192.168.1.3 . The stream is being generated by ffmpeg.

  The video stream can be opened in web browser. But I want to capture it with opencv and python.

• ffmpeg compilation issue on Windows phone 8.1

  24 février 2017, par Mirko Puliafito

  Taking a look at Build ffmpeg for windows phone 8
  I was able to compile ffmpeg on Windows phone 8using these steps :

  My configuration

  OS : Windows 8.1 VS : Ultimate 2013 Update 3 (If armasm fails, msvcdis110.dll missing download it from dllsearch ) Mingw (be sure that "link" and "cl" commands point to MS "link" and "cl") FFmpeg 2.1.5

  Follow prerequisites listed here : https://ffmpeg.org/platform.html#Microsoft-Visual-C_002b_002b-or-Intel-C_002b_002b-Compiler-for-Windows

  -) Download c99toc89 : https://github.com/libav/c99-to-c89/downloads/. Be sure all files from c99toc89 are in Mingw PATH (copy in /bin)

  -) FFMPEG requires stdint.h and inttypes.h headers standardized as a part of C99. Unfortunately, Visual Studio does not include these files. Fortunately, there is a project that fixes this issue. Download the latest version and unpack it to Visual Studio includes (C :\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include).

  -) Launch cmd and "c :\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat x86_arm" and then msys

  -) configure :

  ./configure --toolchain=msvc \
  
  --disable-programs \
  
  --disable-network \
  
  --disable-protocols \
  
  --extra-cflags="-D_ARM_WINAPI_PARTITION_DESKTOP_SDK_AVAILABLE -D_M_ARM -D_WINAPI_FAMILY=WINAPIFAMILY_APP" \
  
  --enable-cross-compile \
  
  --target-os=win32 \
  
  --arch=arm \
  
  --as=armasm \
  
  --cpu=armv7 \
  
  --disable-yasm \
  
  --extra-ldflags="-MACHINE:ARM" \
  
  --disable-dxva2 \
  
  --disable-asm \
  
  --disable-doc

  I was able to get .a static libs but I wasn’t able to generate an app using it. I have problems while linking for kernel32.lib and libcmt.lib misses.

  Anyone ?