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• File created in subprocess.run not found by os.listdir()

  13 novembre 2019, par Abitbol

  I am using subprocess to launch an instance of ffmpeg extracting frames in a folder. Then I do os.listdir on that same folder and it returns an empty list ; off course I would except to see the files created by ffmpeg listed.

  Here is a minimal example

  import os
  
  import subprocess
  
  
  
  folder = 'generated'
  
  subprocess.run(['ffmpeg', '-i', 'input.mp4', '-vf', 'fps=4', f'{folder}/%05d.png'])
  
  print(os.listdir(folder))  # []

  I can testify that the files are created while the script is running.

  In the full example I am using ffmpeg complex filter to generate two output, I don’t think that is the source of the problem.

• How to write command in android when I m using FFmpeg Native with C++ file ?

  16 octobre 2019, par axita.savani

  Using FFmpeg lastest version ("Ada") with native code and write command in android .cpp file below it’s very simple function VideogetDuration() :

  #include 
  
  #include <string>
  
  #include <iostream>
  
  #include <android></android>log.h>
  
  #include 
  
  
  
  extern "C" {
  
  #include <libavutil></libavutil>timestamp.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavutil></libavutil>display.h>
  
  }
  
  
  
      /***
  
       *
  
       * @param input - the absolute path to file
  
       * @returns the duration of file in seconds
  
       *
  
       */
  
      extern "C"
  
      JNIEXPORT jint JNICALL
  
      Java_com_ffmpegjni_videoprocessinglibrary_VideoProcessing_getDuration(JNIEnv *env,
  
                                                                            jobject instance,
  
                                                                            jstring input_) {
  
          av_register_all();
  
          AVFormatContext *pFormatCtx = NULL;
  
          if (avformat_open_input(&amp;pFormatCtx, jStr2str(env, input_), NULL, NULL) &lt; 0) {
  
              throwException(env, "Could not open input file");
  
              return 0;
  
          }
  
  
  
  
  
          if (avformat_find_stream_info(pFormatCtx, NULL) &lt; 0) {
  
              throwException(env, "Failed to retrieve input stream information");
  
              return 0;
  
          }
  
  
  
          int64_t duration = pFormatCtx->duration;
  
  
  
  
  
          avformat_close_input(&amp;pFormatCtx);
  
          avformat_free_context(pFormatCtx);
  
          return (jint) (duration / AV_TIME_BASE);
  
      }
  
  </iostream></string>

  when this value returns 0 value either the wrong value.
  also i have read the below docs for more information.
  1)http://dranger.com/ffmpeg/data.html
  2)https://static.packt-cdn.com/downloads/Developing_Multimedia_Applications_with_NDK.pdf
  3)https://github.com/KucherenkoIhor/VideoProcessingLibrary (also see this project)
  4)https://github.com/leandromoreira/ffmpeg-libav-tutorial#video---what-you-see

  i have also add the same problem with below link :
  how to use libavcodec/ffmpeg to find duration of video file

• Why MediaArea_MediaInfo, AlturosDestinations_Alturos.VideoInfo and Xabe.FFmpeg work in C# console and winforms applications but not in UWP apps ?

  15 octobre 2020, par Morteza

  I want to get video files metadata. I used MediaInfo, AlturosVideoInfo and Xabe.FFmpeg. AlturosVideoInfo and MediaInfo return null but Xabe.FFmpeg returns an exception that says Invalid File (Can't open the file).

  


  I think the problem is limitations in accessing files in UWP, but I added the folder that contains video files to FutureAccessList and even used FileOpenPicker.

  


  How can I use these tools to get video metadata in UWP ?

  


  Thank you