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• ffmpeg webcam capture a/v out of sync

  7 juillet 2014, par Cameron Ball

  I’m running this command to capture video and audio from my webcam :

  ffmpeg -y -f video4linux2 -s 320x240 -i /dev/video0 -f alsa -i "plughw:CARD=U0x46d0x825,DEV=0" -ac 2 -strict experimental Filename.mp4

  It works, but the audio is about half a second behind the video (EG if I clap, when I watch the video I’ll hear the clap and then see me do it).

  This is for an online stream, so I can’t fix it up later, it needs to be recorded correctly.

  It always seems to be off by the same amount, so I’m trying to find an option to simply delay when audio starts recording, but I can’t figure it out.

  Any ideas ?

• Progress with rtc.io

  12 août 2014, par silvia

  At the end of July, I gave a presentation about WebRTC and rtc.io at the WDCNZ Web Dev Conference in beautiful Wellington, NZ.

  

  Putting that talk together reminded me about how far we have come in the last year both with the progress of WebRTC, its standards and browser implementations, as well as with our own small team at NICTA and our rtc.io WebRTC toolbox.

  

  One of the most exciting opportunities is still under-exploited : the data channel. When I talked about the above slide and pointed out Bananabread, PeerCDN, Copay, PubNub and also later WebTorrent, that’s where I really started to get Web Developers excited about WebRTC. They can totally see the shift in paradigm to peer-to-peer applications away from the Server-based architecture of the current Web.

  Many were also excited to learn more about rtc.io, our own npm nodules based approach to a JavaScript API for WebRTC.

  

  We believe that the World of JavaScript has reached a critical stage where we can no longer code by copy-and-paste of JavaScript snippets from all over the Web universe. We need a more structured module reuse approach to JavaScript. Node with JavaScript on the back end really only motivated this development. However, we’ve needed it for a long time on the front end, too. One big library (jquery anyone ?) that does everything that anyone could ever need on the front-end isn’t going to work any longer with the amount of functionality that we now expect Web applications to support. Just look at the insane growth of npm compared to other module collections :

  

  For those that – like myself – found it difficult to understand how to tap into the sheer power of npm modules as a font end developer, simply use browserify. npm modules are prepared following the CommonJS module definition spec. Browserify works natively with that and “compiles” all the dependencies of a npm modules into a single bundle.js file that you can use on the front end through a script tag as you would in plain HTML. You can learn more about browserify and module definitions and how to use browserify.

  For those of you not quite ready to dive in with browserify we have prepared prepared the rtc module, which exposes the most commonly used packages of rtc.io through an “RTC” object from a browserified JavaScript file. You can also directly download the JavaScript file from GitHub.

  

  So, I hope you enjoy rtc.io and I hope you enjoy my slides and large collection of interesting links inside the deck, and of course : enjoy WebRTC ! Thanks to Damon, JEeff, Cathy, Pete and Nathan – you’re an awesome team !

  On a side note, I was really excited to meet the author of browserify, James Halliday (@substack) at WDCNZ, whose talk on “building your own tools” seemed to take me back to the times where everything was done on the command-line. I think James is using Node and the Web in a way that would appeal to a Linux Kernel developer. Fascinating !!

• How to make video from images using Java + x264 ; cross platform solution required

  19 octobre 2014, par Shashank Tulsyan

  I have made a software which records my entire day into a video.
  Example video : https://www.youtube.com/watch?v=ITZYMMcubdw (Note : >16hrs compressed in 2mins, video speed too high, might cause epilepsy :P )

  The approach that I use right now is, Avisynth + x264 + Java.
  This is very very efficient. The video for entire day is created in 3-4mins, and reduced to a size of 40-50MB. This is perfect, the only issue is that this solution is not cross platform.
  Does anyone have a better idea ?

  I tried using java based x246 libraries but

  1. They are slow as hell
  2. The video output size is too big
  3. The video quality is not satisfactory.

  Some website suggest a command such as :

  x264.exe --crf 18 --fps 24 --input-res 1920x1080 --input-csp rgb -o "T:\crf18.mkv" "T:\___BBB\big_buck_bunny_%05d.png"

  There are 2 problems with this approach.

  1. As far as I know, x264 does accept image sequence as input, ffmpeg does
  2. The input images are not named in sequence such as image01.png , image02.png etc. They are named as timestamp_as_longinteger.png . So inorder to allow x264 to accept these images as input, I have to rename all of them ( i make a symbolic link for all images in a new folder ). This approach is again unsatisfactory, because I need more flexibility in selecting/unselecting files which would be converted to a video. Right now my approach is a hack.

  The best solution is x264. But not sure how I can send it an image sequence from Java. That too, images which are not named in sequential fashion.

  ---

  BTW The purpose of making video is going back in time, and finding out how time was spend/wasted.
  The software is aware of what the user is doing. So using this I can find out (visually) how a class evolved with time. How much time I spend on a particular class/package/module/project/customer. The granuality right now is upto the class level, I wish to take it to the function level. The software is called jitendriya.

  

  ---

  Here is 1 solution
  How does one encode a series of images into H264 using the x264 C API ?

  But this is for C. If I have to do the same in java, and in a cross plaform fashion, I will have to resort to JNA/JNI. JNA might have a significant performance hit. JNI would be more work.
  FFMpeg also looks like a nice alternative, but I am still not satisfied by any of these solutions looking at the pros and cons.

  ---

  Solution Adapted.

  package weeklyvideomaker;
  
  
  
  import java.awt.AWTException;
  
  import java.awt.Rectangle;
  
  import java.awt.Robot;
  
  import java.awt.Toolkit;
  
  import java.awt.image.BufferedImage;
  
  import java.io.File;
  
  import java.io.IOException;
  
  import java.io.OutputStream;
  
  import java.util.Calendar;
  
  import java.util.LinkedList;
  
  import java.util.logging.Level;
  
  import java.util.logging.Logger;
  
  import neembuu.release1.util.StreamGobbler;
  
  import org.shashaank.activitymonitor.ScreenCaptureHandler;
  
  import org.shashaank.jitendriya.JitendriyaParams;
  
  
  
  /**
  
   *
  
   * @author Shashank
  
   */
  
  public class DirectVideoScreenHandler implements ScreenCaptureHandler {
  
      private final JitendriyaParams  jp;
  
  
  
      private String extension="264";
  
      private boolean lossless=false;
  
      private String fps="24/1";
  
  
  
      private Process p = null;
  
      private Rectangle r1;
  
      private Robot r;
  
  
  
      private int currentDay;
  
  
  
      private static final String[]weeks={"sun","mon","tue","wed","thu","fri","sat"};
  
  
  
      public DirectVideoScreenHandler(JitendriyaParams jp) {
  
          this.jp = jp;
  
      }
  
  
  
      public String getExtension() {
  
          return extension;
  
      }
  
  
  
      public void setExtension(String extension) {
  
          this.extension = extension;
  
      }
  
  
  
      public boolean isLossless() {
  
          return lossless;
  
      }
  
  
  
      public void setLossless(boolean lossless) {
  
          this.lossless = lossless;
  
      }
  
  
  
      public String getFps() {
  
          return fps;
  
      }
  
  
  
      public void setFps(String fps) {
  
          this.fps = fps;
  
      }
  
  
  
      private static int getday(){
  
          return Calendar.getInstance().get(Calendar.DAY_OF_WEEK) - 1;
  
      }
  
  
  
      public void make()throws IOException,AWTException{
  
          currentDay = getday();
  
          File week = jp.getWeekFolder();
  
  
  
          String destinationFile = week+"\\videos\\"+weeks[currentDay]+"_"+System.currentTimeMillis()+"_direct."+extension;
  
  
  
          r = new Robot();
  
          r1 = getScreenSize();
  
  
  
          ProcessBuilder pb = makeProcess(destinationFile, 0, r1.width, r1.height);
  
  
  
          p = pb.start();
  
          StreamGobbler out = new StreamGobbler(p.getInputStream(), "out");
  
          StreamGobbler err = new StreamGobbler(p.getErrorStream(), "err");
  
          out.start();err.start();
  
      }
  
  
  
      private static Rectangle getScreenSize(){
  
          return new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
  
      }
  
  
  
      private void screenShot(OutputStream os)throws IOException{        
  
          BufferedImage bi = r.createScreenCapture(r1);
  
          int[]intRawData = ((java.awt.image.DataBufferInt)
  
                  bi.getRaster().getDataBuffer()).getData();
  
          byte[]rawData = new byte[intRawData.length*3];
  
          for (int i = 0; i < intRawData.length; i++) {
  
              int rgb = intRawData[i];
  
              rawData[ i*3 + 0 ] = (byte) (rgb >> 16);
  
              rawData[ i*3 + 1 ] = (byte) (rgb >> 8);
  
              rawData[ i*3 + 2 ] = (byte) (rgb);
  
          }
  
          os.write(rawData);
  
      }
  
  
  
      private ProcessBuilder makeProcess(String destinationFile, int numberOfFrames,
  
              int width, int height){
  
          LinkedList<string> commands = new LinkedList&lt;>();
  
          commands.add("\""+encoderPath()+"\"");
  
          if(true){
  
              commands.add("-");
  
              if(lossless){
  
                  commands.add("--qp");
  
                  commands.add("0");
  
              }
  
              commands.add("--keyint");
  
              commands.add("240");
  
              commands.add("--sar");
  
              commands.add("1:1");
  
              commands.add("--output");
  
              commands.add("\""+destinationFile+"\"");
  
              if(numberOfFrames>0){
  
                  commands.add("--frames");
  
                  commands.add(String.valueOf(numberOfFrames));
  
              }else{
  
                  commands.add("--stitchable");
  
              }
  
              commands.add("--fps");
  
              commands.add(fps);
  
              commands.add("--input-res");
  
              commands.add(width+"x"+height);
  
              commands.add("--input-csp");
  
              commands.add("rgb");//i420
  
          }
  
          return new ProcessBuilder(commands);
  
      }
  
  
  
      private String encoderPath(){
  
          return jp.getToolsPath()+File.separatorChar+"x264_64.exe";
  
      }
  
  
  
      @Override public void run() {
  
          try {
  
              if(p==null){
  
                  make();
  
              }
  
              if(currentDay!=getday()){// day changed
  
                  destroy(); 
  
                  return;
  
              }
  
              if(!r1.equals(getScreenSize())){// screensize changed
  
                  destroy();
  
                  return;
  
              }
  
              screenShot(p.getOutputStream());
  
          } catch (Exception ex) {
  
              Logger.getLogger(DirectVideoScreenHandler.class.getName()).log(Level.SEVERE, null, ex);
  
          }
  
      }
  
  
  
      private void destroy()throws Exception{
  
          p.getOutputStream().flush();
  
          p.getOutputStream().close();
  
          p.destroy();
  
          p = null;
  
      }
  
  
  
  }
  
  </string>

  ---

  package weeklyvideomaker;
  
  
  
  import org.shashaank.jitendriya.JitendriyaParams;
  
  
  
  /**
  
   *
  
   * @author Shashank
  
   */
  
  public class DirectVideoScreenHandlerTest {
  
      public static void main(String[] args)throws Exception {
  
          JitendriyaParams  jp = new JitendriyaParams.Builder()
  
                  .setToolsPath("F:\\GeneralProjects\\JReminder\\development_environment\\tools")
  
                  .setOsDependentDataFolderPath("J:\\jt_data")
  
                  .build();
  
          DirectVideoScreenHandler w = new DirectVideoScreenHandler(jp);
  
          w.setExtension("264");
  
          w.setFps("24/1");
  
          w.setLossless(false);
  
          w.make();
  
  
  
          for (int i = 0; ; i++) {
  
              w.run();
  
              Thread.sleep(1000);
  
          }
  
      }
  
  }