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• Including ffmpeg in qt project on windows causes the program to unexpectedly finish

  1er avril 2016, par Burn-Man

  I am trying to include ffmpeg in my qt project on windows. I am running QT4 and compiling with microsoft visual compiler 2010 on 32 bit windows 7. I am trying to include ffmpeg 2.8 which I got the dev and shared downloads from zeranoe. When I run it I get the following output :

  Starting (executable path)...
  
  The program has unexpectedly finished.
  
  (executable path) exited with code -1073741819

  I am able to produce this output with the following :

  ffmpeg_test.pro :

  QT += core
  
  TARGET = ffmpeg_test
  
  
  
  INCLUDEPATH += (ffmpeg dev path)/include
  
  LIBS += -L(ffmpeg dev path)/lib
  
  LIBS += -lavformat
  
  
  
  SOURCES += main.cpp

  main.cpp :

  extern "C"
  
  {
  
  #ifndef __STDC_CONSTANT_MACROS
  
  #define __STDC_CONSTANT_MACROS
  
  #endif
  
  #include <libavformat></libavformat>avformat.h>
  
  }
  
  
  
  int main(int argc, char *argv[])
  
  {
  
    av_register_all();
  
    return 0;
  
  }

  I have put the .dll files from the ffmpeg share bin into the same folder that QT builds ffmpeg_test.exe into. I have also confirmed that they are found using dependency walker which shows a question mark when they are not in that directory and the avformat-56.dll file path when they are (the fact that the .dll files are found does not effect the output of the program).

  Dependency walker does reveal that something weird is going on as there are no expected functions, but the functions found in avformat-56.dll look correct. I also have ran Dumpbin.exe /EXPORTS on avformat.lib and it also looks fine (I can post output if it would be helpful). It is worth noting that I have included this version of ffmpeg in a different application on this machine, it was not a qt project however. That project generated its make file with CMake rather than QMake and was built with Microsoft Visual C++ 2010 rather than QT Creator.

  I have also included other .lib/.dll pairs in qt and they have no problems. I am noticing two differences from those pairs. First in the ffmpeg-dev lib folder instead of having only .lib files (as is the case for all my other .lib/.dll pairs) I also have a .def and a .dll.a file for each library. Second ffmpeg is a c library whereas all my other included libraries are c++.

  update 3/29 :

  I have tried replacing the LIBS lines in my .pro with both of the following :

  LIBS += (ffmpeg dev path)/lib/avformat.lib

  LIBS += (ffmpeg dev path)/lib/libavformat.dll.a

  Both give the same error message. I have also tried adding the following to my .pro file also with no effect.

  DEFINES += __STDC_CONSTANT_MACROS
QMAKE_CXX_FLAGS += -D_STDC_CONSTANT_MACROS

  Additionally I tried adding #define inline __inline to main.cpp as suggested on the ffmpeg website. Any ideas of things to try would be hugely appreciated !

  update 3/31 :

  I have tried to start over with a new Windows build environment but the result remains unchanged with the test code above. (The new environment was able to run a hello world program).

  My process for setting up this environment was to install a fresh version of 32 bit windows 7. Install Visual C++ 2010 Express from the Visual Studio 2010 Express All-in-one ISO. Install Qt 4.8.6 for 32 bit windows and Visual Studio 2010. And finally install Qt Creator 2.5.2. To set up Qt creator I went under tools->options and told it where to find the Qt 4.8.6 qmake. I downloaded the dev and shared builds for ffmpeg 2.8 from Zeranoe. I was missing stdint.h and inttypes so I downloaded them and put the files in /include/libavutil. Then I corrected any of the header files that complained from to "stdint.h" ect. I then put the dll files from ffmpeg-2.8-win32-shared/bin into the folder where qt was building ffmpeg_test ffmpeg_test-build-desktop-Qt_4_8_6__4_8_6__Release/release.

• Screen Recorder .Net SDK [on hold]

  15 novembre 2017, par ShankarSangoli

  I want to record my Selenium automated tests which are written in C#.

  I am planning to write a .Net console application which will start a screen recorder and at the same time, start the Selenium automated tests. I was looking for any available Screen Recorder .Net library which can be incorporated in the .Net console application. But I could not find anything useful which will help me to record the video in mp4 format with audio(optionally).

  I have already looked at Microsoft Expression Encoder 4 SDK but it has several limitations and also it cannot record video in .mp4 format unless you use Pro version which is not easily available.

  Can anyone please provide a pointer to any helpful resources ?

• Pause a FFmpeg encoding in a Python Popen subprocess on Windows

  5 décembre 2020, par CasualDemon

  I am trying to pause an encode of FFmpeg while it is in a non-shell subprocess (This is important to how it plays into a larger program). This can be done by presssing the "Pause / Break" key on the keyboard by itself, and I am trying to send that to Popen.

  


  The command itself must be cross platform compatible, so I cannot wrap it in any way, but I can send signals or run functions that are platform specific as needed.

  


  I looked at how to send a "Ctrl+Break" to a subprocess via pid or handler and it suggested to send a signal, but that raised a "ValueError : Unsupported signal : 21"

  


  from subprocess import Popen, PIPE
import signal


if __name__ == '__main__':
    command = "ffmpeg.exe -y -i example_video.mkv -map 0:v -c:v libx265 -preset slow -crf 18 output.mkv"
    proc = Popen(command, stdin=PIPE, shell=False)

    try:
        proc.send_signal(signal.SIGBREAK)
    finally:
        proc.wait()


  


  Then attempted to use GenerateConsoleCtrlEvent to create a Ctrl+Break event as described here https://docs.microsoft.com/en-us/windows/console/generateconsolectrlevent

  


  from subprocess import Popen, PIPE
import ctypes


if __name__ == '__main__':
    command = "ffmpeg.exe -y -i example_video.mkv -map 0:v -c:v libx265 -preset slow -crf 18 output.mkv"
    proc = Popen(command, stdin=PIPE, shell=False)

    try:
        ctypes.windll.kernel32.GenerateConsoleCtrlEvent(1, proc.pid)
    finally:
        proc.wait()


  


  I have tried psutil pause feature, but it keeps the CPU load really high even when "paused".

  


  Even though it wouldn't work with the program overall, I have at least tried setting creationflags=CREATE_NEW_PROCESS_GROUP which makes the SIGBREAK not error, but also not pause it. For the Ctrl-Break event will entirely stop the encode instead of pausing it.