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• Live video from raw tcp packets

  7 juin 2017, par benuuts

  we are trying to make a small python app that display a live video from sniffed packets using scapy and ffplay. This is part of our master degree research project. The goal is to make a proof of concept app that spies on video transimitted over tcp.
  We have a working script that writes into a .dat file and then we read it using ffplay. It works ok but have a lot of latency and we think we could do better : directly stream it into ffplay without the need to write raw data in a file.

  Here’s our script :

  from scapy.all import * 
  
  import os
  
  
  
  export_dat = open("data.dat", "a")
  
  
  
  def write_packet_raw(packet):
  
      export_dat.write(str(packet.getlayer(Raw)))
  
  
  
  def realtime_packet():
  
      p = sniff(iface="wlan0", filter="tcp and (port 5555)", count=5000, prn=write_packet_raw)
  
  
  
  realtime_packet()
  
  export_dat.close()

  And then we launch : ffplay -window_title Videostream -framedrop -infbuf -f h264 -i data.dat

  Any idea on how we can achieve that ? thanks.

• Matplotlib animation quality loss

  28 juin 2017, par Doe a

  I’m currently trying to use matplotlib to animate a grid using imshow. However, I am finding a fairly significant quality loss in the animation.

  Below is a simple animation that illustrates my issue fairly well. If you look at any particular frame of imagelist, you will see that there is no aliasing or gradient between colours. But if I then look at one frame of my animation, that is no longer the case. There is now a 4-5 pixel gradient between my blocks of colour. Does anyone know how I can get around this compression ? The file size of the animation doesn’t matter too much, as long as I can get a good quality animation.

  #Create list of images
  
  image=np.array([[[0,0,0],(0.7,0,0),(0,0,0),(0,0,0.8)]])
  
  imagelist=[]
  
  for i in range(0,100):
  
      image[0][1][0]=i/100
  
      imagelist.append(np.copy(image))
  
  
  
  #Create figure    
  
  fig = plt.figure()
  
  plt.axis('off')
  
  im = plt.imshow(imagelist[0], vmin=0, vmax=255,interpolation='none');
  
  
  
  #Animation
  
  def updatefig(j):
  
      im.set_array(imagelist[j])
  
      return [im]
  
  ani = animation.FuncAnimation(fig, updatefig, frames=range(len(imagelist)), interval=20, blit=False)
  
  
  
  #Save animation
  
  FFMpegWriter = animation.writers['ffmpeg']
  
  mywriter = FFMpegWriter(fps=30, bitrate=5000)
  
  ani.save("test.mp4", writer=mywriter,codec="libx264")

• How to stop recording dynamically in FFMPEG CLI Wrapper java

  14 décembre 2017, par user2237529

  https://github.com/bramp/ffmpeg-cli-wrapper/issues/13

  public class ScreenCaptureFFMPEG {
  
  
  
      public static void record(String outputVideo, String time) throws Exception
  
      {
  
          RunProcessFunction func = new RunProcessFunction();
  
  
  
          FFmpeg ffmpeg = new FFmpeg("C:\\FFMPEG\\ffmpeg.exe");
  
          FFmpegBuilder builder = new FFmpegBuilder()
  
                  .addExtraArgs("-rtbufsize", "1500M")
  
                  .addExtraArgs("-r", "30")
  
                  .setFormat("dshow")
  
                  .setInput("video=\"screen-capture-recorder\"")
  
                  .addOutput(outputVideo)
  
                  .setFormat("mp4")
  
                  .addExtraArgs("-crf", "0")
  
                  .setVideoCodec("libx264")
  
                  //.addExtraArgs("-ac", "1")
  
                  .addExtraArgs("-y")
  
          //overwrite file name
  
  
  
                  // .setAudioCodec("libmp3lame")
  
                  // .setAudioSampleRate(FFmpeg.AUDIO_SAMPLE_44100)
  
                  //  .setAudioBitRate(1_000_000)
  
  
  
                  //.addExtraArgs("-ar", "44100")
  
                  .addExtraArgs("-t", time)
  
  
  
                  //.setVideoPixelFormat("yuv420p")
  
                  //.setVideoResolution(426, 240)
  
                  //.setVideoBitRate(2_000_000)
  
                  //.setVideoFrameRate(30)
  
                  //.addExtraArgs("-deinterlace")
  
                  //.addExtraArgs("-preset", "medium")
  
                  //.addExtraArgs("-g", "30")
  
                  .done();
  
          FFmpegExecutor executor = new FFmpegExecutor(ffmpeg);
  
  
  
          executor.createJob(builder).run();
  
  
  
  
  
      }
  
  
  
      public static void capture(String name) throws Exception
  
      {
  
          BufferedImage image = new Robot().createScreenCapture(new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()));
  
          ImageIO.write(image, "png", new File(name));
  
  
  
      }
  
  
  
      public static void main(String[]args) throws Exception {
  
  
  
          capture("start.png");
  
          //record("TC_test.mp4", "00:00:10");
  
          capture("end.png");
  
          Thread t = new Thread(new Runnable() {
  
              @Override
  
              public void run() {
  
                  // Insert some method call here.
  
                  try {
  
                      record("TC_test.mp4", "00:00:10");
  
                  }
  
                  catch(Exception e)
  
                  {
  
                      System.out.println("hello");
  
                  }
  
              }
  
          });
  
          Thread.sleep(5000);
  
  
  
          t.interrupt();
  
  
  
      }
  
  }

  I am trying to stop the recording by killing the subprocess or if there is any other method its fine too. But I am unable to do that. I know its supported according to the github link. How do I kill a subprocess please ?

  PS : THis is the first time i post a question on stackoverflow so If I made any mistakes please excuse me and provide details on how i can improve