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• application using ffmpeg segfaults because of for loop ?

  6 décembre 2012, par larvyde

  I am writing my first ffmpeg application using the tutorial linked to from the ffmpeg.org documentation page [tutorial] [sample]. Here is my initial code :

  const char * fnmVideoIn = argv [1];
  
  const char * fnmImageOut = argv [2];
  
  
  
  av_register_all ();
  
  
  
  // [] Open the file
  
  AVFormatContext * pcxFormat;
  
  if (avformat_open_input (&pcxFormat, fnmVideoIn, NULL, NULL)) {
  
      fprintf (stderr, "Could not open file %s for reading\n",
  
              fnmVideoIn);
  
      return -1;
  
  }
  
  
  
  // [] Get stream information
  
  if (avformat_find_stream_info (pcxFormat, NULL) < 0) {
  
      fprintf (stderr, "Could not find stream info\n");
  
      return -1;
  
  }
  
  
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);

  and all is well. The program runs without errors and dumps the video info properly. but then I got to the next step...

  ...
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);
  
  
  
  int ixVideoStream = -1, ixStrm;
  
  for (ixStrm = 0; ixStrm < pcxFormat->nb_streams; ++ixStrm) {
  
      if (pcxFormat->streams [ixStrm]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          ixVideoStream = ixStrm;
  
          break;
  
      }
  
  }

  and it exits with a segfault. gdb says :

  (gdb) r test.mp4 out
  
  ...
  
  Program received signal SIGSEGV, Segmentation fault.
  
  0xb7f572c5 in avformat_open_input () from /usr/lib/libavformat.so.53

  how is it possible that avformat_open_input segfaults because of code added after it is called ? I even tested it with a regular i=0 ; i<100 for-loop and it still segfaults ! is this a bug ? For reference, my system is :

  $ gcc --version
  
  gcc (GCC) 4.7.0 20120414 (prerelease)
  
  
  
  $ uname -srvmpio
  
  Linux 3.3.4-1-ARCH #1 SMP PREEMPT Sat Apr 28 06:04:27 UTC 2012 i686 Intel(R) Core(TM)2 Duo CPU P7450 @ 2.13GHz GenuineIntel GNU/Linux
  
  
  
  $ ffmpeg -version
  
  ffmpeg version 0.10.2
  
  built on Mar 17 2012 08:53:01 with gcc 4.6.3
  
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-libgsm --enable-libspeex --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-libpulse --enable-gpl --enable-version3 --enable-runtime-cpudetect --disable-debug --disable-static
  
  libavutil      51. 35.100 / 51. 35.100
  
  libavcodec     53. 61.100 / 53. 61.100
  
  libavformat    53. 32.100 / 53. 32.100
  
  libavdevice    53.  4.100 / 53.  4.100
  
  libavfilter     2. 61.100 /  2. 61.100
  
  libswscale      2.  1.100 /  2.  1.100
  
  libswresample   0.  6.100 /  0.  6.100
  
  libpostproc    52.  0.100 / 52.  0.100

• How to fix : GUI application who control a simple command of ffmpeg with python

  9 octobre 2019, par maoca

  I want to make a graphic application with only 2 buttons (start / stop) that allows to launch a subprocess (start) and stop it (stop).
  (I’m using Python3, PyQt5 and ffmpeg)
  The process captures the screen in a video and save it to an mp4 using the ffmpeg command to launch the POpen command.
  To make a clean output of the command, ffmpeg uses ’q’ that I write by stdin.

  In a simple script it works for me but I can’t get it to work within the buttons.

  My knowledge is very basic and as much as I look for information I do not understand what I am doing wrong, I appreciate any comments that let me move on.

  This is my code :

  import sys
  
  import subprocess
  
  from PyQt5.QtWidgets import QApplication, QWidget, QPushButton
  
  
  
  class Ventana(QWidget):
  
  
  
      def __init__(self):
  
          super().__init__()
  
          # Button 1
  
          pybutton = QPushButton('REC', self)
  
          pybutton.clicked.connect(self.clickMethodB1)
  
          pybutton.resize(50, 32)
  
          pybutton.move(50, 50)
  
  
  
          # BOTON 2
  
          pybutton = QPushButton('STOP', self)
  
          pybutton.clicked.connect(self.clickMethodB2)
  
          pybutton.resize(100, 32)
  
          pybutton.move(150, 50)
  
  
  
  
  
          self.initUI()
  
  
  
  
  
      def initUI(self):
  
          self.setGeometry(300, 300, 300, 220)
  
          self.setWindowTitle('FFMPEG')
  
          self.move(800, 400)
  
          self.show()
  
  
  
      def clickMethodB1(self):
  
          global ffmpeg
  
          filename_mp4 = 'c://tmp//output.mp4'
  
          print('REC')
  
  
  
          command = 'ffmpeg -f dshow -i video="screen-capture-recorder" '+ filename_mp4
  
  
  
          ffmpeg = subprocess.Popen(command, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE,                                                    encoding='utf-8', shell=True)
  
  
  
  
  
      def clickMethodB2(self):
  
  
  
          print('STOP')
  
          ffmpeg.stdin.write(str('q'))            
  
  
  
  
  
  if __name__ == '__main__':
  
      app = QApplication(sys.argv)
  
      ex = Ventana()
  
      sys.exit(app.exec_())

• trying to include ffmpeg in angular electron application - build fails on require()

  3 mai 2023, par Blair Holmes

  I have found a lot of resources for adding ffmpeg to my windows desktop application built with electron from my angular web app but I can't seem to get my project to build when I try and run it.

  &#xA;

  this is a pretty straight forward tutorial here : https://alexandercleasby.dev/blog/use-ffmpeg-electron

  &#xA;

  My problem comes in the require statements or when I try to use the modules via import, whenever I try to access the imported modules.

  &#xA;

  I get errors like this :

  &#xA;

  &#xA;

  Error : ./node_modules/ffprobe-static/index.js Module not found : Error :&#xA;Can't resolve 'os' in&#xA;'C :\Users\MyUser\source\repos\my-app\my-app-angular-desktop\node_modules\ffprobe-static'&#xA;resolve 'os' in&#xA;'C :\Users\MyUser\source\repos\my-app\my-app-angular-desktop\node_modules\ffprobe-static'&#xA;Parsed request is a module using description file :&#xA;C :\Users\MyUser\source\repos\my-app\my-app-angular-desktop\node_modules\ffprobe-static\package.json&#xA;(relative path : .)&#xA;Field 'browser' doesn't contain a valid alias configuration&#xA;resolve as module&#xA;looking for modules in C :/Users/MyUser/source/repos/my-app/my-app-angular-desktop&#xA;using description file : C :\Users\MyUser\source\repos\my-app\my-app-angular-desktop\package.json&#xA;(relative path : .)&#xA;Field 'browser' doesn't contain a valid alias configuration&#xA;using description file : C :\Users\MyUser\source\repos\my-app\my-app-angular-desktop\package.json&#xA;(relative path : ./os)&#xA;no extension&#xA;Field 'browser' doesn't contain a valid alias configuration&#xA;C :\Users\MyUser\source\repos\my-app\my-app-angular-desktop\os doesn't&#xA;exist

  &#xA;

  &#xA;

  Should I be trying to build with webpack directly instead of ng build ? I have never done that with an angular application so I"m not sure what steps I'd need to take.

  &#xA;

  I'm currently on angluar 11 with webpack 4.44.2.

  &#xA;