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• java.lang.NoClassDefFoundError : Could not initialize class on Linux (Works fine on Windows)

  26 décembre 2016, par Jake Miller

  I’m using a C++ FFmpeg wrapper for Java (org.bytedeco.javacpp). This works perfectly on a Windows machine (my development machine) but throws this error when ran on Linux (Amazon Web Services Elastic Beanstalk) :

  java.lang.NoClassDefFoundError: Could not initialize class org.bytedeco.javacpp.avutil
  
      at java.lang.Class.forName0(Native Method) ~[na:1.8.0_111]
  
      at java.lang.Class.forName(Class.java:348) ~[na:1.8.0_111]
  
      at org.bytedeco.javacpp.Loader.load(Loader.java:472) ~[javacpp-1.2.1.jar!/:1.2.1]
  
      at org.bytedeco.javacpp.Loader.load(Loader.java:417) ~[javacpp-1.2.1.jar!/:1.2.1]
  
      at org.bytedeco.javacpp.avformat$AVFormatContext.<clinit>(avformat.java:2819) ~[ffmpeg-3.2.1-1.3.jar!/:1.2.1]
  
      at org.bytedeco.javacv.FFmpegFrameGrabber.startUnsafe(FFmpegFrameGrabber.java:391) ~[javacv-1.3.jar!/:1.3]
  
      at org.bytedeco.javacv.FFmpegFrameGrabber.start(FFmpegFrameGrabber.java:385) ~[javacv-1.3.jar!/:1.3]
  
  </clinit>

  I’ve been troubleshooting for the past 2 days and have tried the following to fix the issue :

  • upgrade to Linux to 2.4
  • downgrading javacpp to 1.2.1
  • running mvn clean
  • running mvn -U
  • deleting contents of /.m2/ and redownloading dependencies
  • various combinations of dependency versions
  • git clone on a Linux VM & running mvn install there

  When looking further into the issue, I stumbled upon documentation for avformat$AVFormatContext as it’s in the stack trace posted above (6th line). The documentation for a C++ class named AVFormatContext. Whenever I attempt to view the class in Eclipse, it says Source Not Found.

  My question : could this problem possibly be caused by the C++ libraries on my Linux VM ? None of the above solutions fixed it so this is my only hypothesis as of now.

  Here’s my other Stack Overflow question regarding this subject : Java.lang.NoClassDefFoundError caused by FFmpeg when deployed on Linux as a packaged .war (Works on development machine)

• How can I use my exe in a new Process() call ?

  24 février 2017, par looksgoodhoss

  I am working on a project where I create a 10 second sample from a video. To do this, I am using FFMPEG. I would like for the user to upload their own video where the sampling will then take place. The processing will be done in an Azure worker-role and that is where my problem lies.

  If I execute the following command (excuse the absolute paths, they’re my next problem) in Command Prompt then the sampling is completed successfully.

  ffmpeg -t 10 -i C:\Users\looksgoodhoss\Documents\Videos\video.mp4 -map_metadata 0 -acodec copy C:\Users\looksgoodhoss\Documents\Videos\vid.mp4 -y

  I am trying to bring this command into my Visual Studio project via a new Process() call. The video.mp4 and vid.mp4 are trivial names to test and work out my bug.

  bool success = false;
  
              string EXEArguements = @"ffmpeg -t 10 -i C:\Users\looksgoodhoss\Documents\Videos\video.mp4 -map_metadata 0 -acodec copy C:\Users\looksgoodhoss\Documents\Videos\vid.mp4 -y";
  
              string EXEPath = Path.Combine(Environment.GetEnvironmentVariable("RoleRoot") + @"\", @"approot\ffmpeg.exe");
  
  
  
              try
  
              {
  
                  Process proc = new Process();
  
                  //proc.StartInfo.FileName = @"C:\FFMPEG\bin\ffmpeg";
  
                  proc.StartInfo.FileName = EXEPath;
  
                  proc.StartInfo.Arguments = EXEArguements;
  
                  proc.StartInfo.CreateNoWindow = true;
  
                  proc.StartInfo.UseShellExecute = false;
  
                  proc.StartInfo.ErrorDialog = false;
  
  
  
                  Trace.TraceInformation("FFMPEG completed."); // is shown in log
  
  
  
                  proc.Start();
  
                  proc.WaitForExit();
  
                  success = true;
  
              }
  
              catch (Exception e)
  
              {
  
                  throw;
  
              }
  
              return success;

  The message "FFMPEG completed" is shown in the Compute Emulator UI and so I know that this block of code is executing, however, they’re is no sample video created despite the command being the same.

  Am I executing FFMPEG incorrectly in my Visual Studio project ? I think this is my problem because the same command can successfully be performed through Command Prompt.

  Any help or advice would be greatly appreciated,

  Thanks.

• Thumbs depending on the video duration

  28 février 2017, par MaelLacour

  as said in the title, i would like to add thumbs, depending on the video duration.

  It it possible to define time using percentage ? Or to use a variable duration ? I know that the duration can be found in the _meta, but is it possible to retrieve it before saving the video ?
  (I can certainly do it by using ffmpeg command, but it should be available using paperclip command ?)

  Here is my code :

  validates :title,
  
          length: { in: 2..60 }
  
  validates :description,
  
          length: { minimum: 2 }
  
  
  
  
  
  has_attached_file :content, styles: {
  
      :medium => {
  
          :format => 'mp4',
  
          #convert_options: {
  
              #output: {
  
                #name: 'value' # Results in `-name value` in the command line
  
              #}
  
          #}
  
      },
  
    :thumb0 => { :geometry => '320x180#', :format => 'jpeg', :time => 1.0 * duration / 6.0},
  
    :thumb1 => { :geometry => '320x180#', :format => 'jpeg', :time => 2.0 * duration / 6.0},
  
    :thumb2 => { :geometry => '320x180#', :format => 'jpeg', :time => 3.0 * duration / 6.0},
  
    :thumb3 => { :geometry => '320x180#', :format => 'jpeg', :time => 4.0 * duration / 6.0},
  
    :thumb4 => { :geometry => '320x180#', :format => 'jpeg', :time => 5.0 * duration / 6.0},
  
    }, :processors => [:transcoder]
  
  
  
    validates_attachment :content, presence: true,
  
                         content_type: { content_type: /\Avideo\/.*\Z/ },
  
                         size: { :less_than => 2.gigabytes }

  Thx in advance for your reply ! If it’s not clear or if you need extra-data let me know :)

  (I posted my question here, after wrongly posted it in GitHub, don’t be surprise if you found it on the issue repo)

  EDIT

  I made it to work with the following code,even if it’s not elegant at all :

    has_attached_file :content, styles: {
  
        :medium => {
  
            :format => 'mp4',
  
        },
  
        :thumb0 => { :geometry => '320x180#', :format => 'jpeg', :time => ->(attachment) { attachment.instance.method(:style_time_for0) } },
  
        :thumb1 => { :geometry => '320x180#', :format => 'jpeg', :time => ->(attachment) { attachment.instance.method(:style_time_for1) } },
  
        :thumb2 => { :geometry => '320x180#', :format => 'jpeg', :time => ->(attachment) { attachment.instance.method(:style_time_for2) } },
  
        :thumb3 => { :geometry => '320x180#', :format => 'jpeg', :time => ->(attachment) { attachment.instance.method(:style_time_for3) } },
  
        :thumb4 => { :geometry => '320x180#', :format => 'jpeg', :time => ->(attachment) { attachment.instance.method(:style_time_for4) } },
  
        }, :processors => [:transcoder]
  
  
  
    def style_time_for0(meta, _options)
  
      1*meta[:duration].to_f / 6
  
    end
  
    def style_time_for1(meta, _options)
  
      2*meta[:duration].to_f / 6
  
    end
  
    def style_time_for2(meta, _options)
  
      3*meta[:duration].to_f / 6
  
    end
  
    def style_time_for3(meta, _options)
  
      4*meta[:duration].to_f / 6
  
    end
  
    def style_time_for4(meta, _options)
  
      5*meta[:duration].to_f / 6
  
    end

  I should add a loop and a parameter to the style_time_for, but i can’t get it to work. Does someone have an idea ?