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• java bufferedimage array data immediately changes

  26 mars 2016, par ken

      import javax.imageio.ImageIO;
  
  
  
      import org.bytedeco.javacv.FFmpegFrameGrabber;
  
  
  
      public class FrameData 
  
      {   
  
  int count = 0;
  
  int picWidth;
  
  int picHeight;
  
  
  
  BufferedImage img = null;
  
  
  
  //GET FRAME COUNT
  
  public int gf_count(int numofFrames, BufferedImage[] frameArray, String fileLocationsent, String videoNamesent) throws IOException
  
  {        
  
      String fileLocation = fileLocationsent;
  
      String videoName = videoNamesent;
  
  
  
      int frameNums = numofFrames;
  
      int totFrames = 0;
  
  
  
              FFmpegFrameGrabber grab = new FFmpegFrameGrabber(fileLocation + videoName);
  
  
  
          try {   grab.start(); } 
  
          catch (Exception e) {   System.out.println("Unable to grab frames");  }
  
  
  
                      for(int i = 0 ; i < frameNums  ; i++) 
  
          {
  
              try 
  
              {                   
  
                  frameArray[i]= grab.grab().getBufferedImage();
  
                  totFrames = i;  
  
                  File outputfile = new File(fileLocation + "GrayScaledImage" + i + ".jpg");
  
                  ImageIO.write(frameArray[i], "jpg", outputfile);
  
              } 
  
              catch (Exception e) {   /*e.printStackTrace();*/    }
  
          }//END for
  
  
  
                  return totFrames;
  
  
  
      }//END METHOD long getFrameCount()

  Hope someone can explain this to me...
  I am just learning java so here goes...
  I wrote this code to count the number of frames in a .mov file and to test my buffered image array I generated files of the images. As the code is, it works as planned... The problem is immediately after the capturing, if I send the bufferedimages out as files, they all seem to be just the first image. see example below...

      for(int i = 0 ; i < frameNums  ; i++) 
  
          {
  
              try 
  
              {                   
  
                  frameArray[i]= grab.grab().getBufferedImage();
  
                  totFrames = i;  
  
                  File outputfile = new File(fileLocation + "GrayScaledImage" + i + ".jpg");
  
                  ImageIO.write(frameArray[i], "jpg", outputfile);
  
              } 
  
              catch (Exception e) {   /*e.printStackTrace();*/    }
  
          }//END for

  And now if I change that to...

      for(int i = 0 ; i < frameNums  ; i++) 
  
          {
  
              try 
  
              {                   
  
                  frameArray[i]= grab.grab().getBufferedImage();
  
                  totFrames = i;  catch (Exception e) {   /*e.printStackTrace();*/    }}
  
      for(int j = 0; j < frameNums; j++)
  
      {
  
      File outputfile = new File(fileLocation + "GrayScaledImage" + j + ".jpg");
  
                  ImageIO.write(frameArray[j], "jpg", outputfile);
  
      }

  I don’t understand why I am getting the same image repeatedly.
  If further information Is required, just lemme know, this is my first programming question online... Usually find what I am looking for that others have asked. Couldn’t find this one.
  Thanks for your time
  Ken

• Nodejs - Using ffmpeg with video thumbnails

  8 mars 2016, par RunningFromShia

  I am pretty much lost within the concept of ffmpeg and nodejs. ffmpeg is supposed to do important conversion work, that I get, but every time I try to implement a nodejs package with ffmpeg it just fails. I will give an example :

  using this for example in my app :
  https://www.npmjs.com/package/video-thumb

  my app.js :

  var express = require('express');
  
  var app = express();    
  
  
  
  var thumbler = require('video-thumb');
  
  
  
  thumbler.extract('http://www.w3schools.com/html/mov_bbb.mp4', 'snapshot.png', '00:00:1', '200x125', function(){
  
  
  
      console.log('snapshot saved to snapshot.png (200x125) with a frame at 00:00:1');
  
  
  
  });
  
  
  
  var port = process.env.PORT || 1337;
  
  
  
  app.listen(port);  

  Basically, I’ve tried a couple of nodejs packages that turn a snapshot out of a given video, and then save it to my server. each attempt failed. they all use ffmpeg. the above is just one of them.

  Now, I put a ffmpeg.exe in my root folder, I am just not sure where it’s supposed to be or how to use it with node. Needless to say, the above example doesn’t do anything. Tutorials online only show how to convert a certain video to a certain format in windows using ffmpeg, there is nothing about nodejs.
  I’d like some guidance here, thank you for your time.

• How to handle queueing of video encoding during multiple video uploads ?

  6 mars 2016, par Yash Desai

  I am working on developing a video streaming site where users can upload videos to the site (multiple videos at once using the uploadify jquery plugin).

  Now, I am faced with the question of encoding the videos to FLV for streaming them online.

  When should the video encoding process take place ? Should it take place immediately after uploads have finished (i.e redirect the user to upload success page, and then start encoding in the background using exec command for ffmpeg ?) However, using this approach, how do i determine if the encoding has finished successfully ? What if users upload a corrupt video and ffmpeg fails to encode it ? How do i handle this in PHP ?

  How do i queue encoding of videos since multiple users can upload videos at the same ? Does FFMpeg has its own encoding queue ?

  I also read about gearman and message queueing options such as redis and AMQP in another related SO thread. Are these one of the potential solutions ?

  I would really appreciate if someone could give answers to my questions.