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• 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

• ffmpeg overlay video with audio

  2 août 2017, par ravindu1024

  I have two video files : input.mp4 (55seconds) and overlay.mp4 (10seconds). I need to overlay the overlay.mp4 on input.mp4 between 00:00:5 and 00:00:15 with both audio streams audible.
  I am using this command and everything seems to work ok but its causing a buffer overflow and causes the overlaid video to freeze and flicker. What am I doing wrong here ?

  ffmpeg -i input.mp4 -i overlay.mp4 -strict -2 -filter_complex
  
  "[0:v]setpts=PTS-STARTPTS[v0];
  
   [1:v]setpts=PTS-STARTPTS+5/TB[v1];
  
   [v0][v1]overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2:eof_action=pass[outv];
  
   [1:a]adelay=5000[a1];
  
   [0:a][a1] amix [outa]"
  
   -map [outv] -map [outa] out.mp4

  Log :

  Output #0, mp4, to 'out.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf56.40.101
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 12800 tbn, 25 tbc (default)
  
      Metadata:
  
        encoder         : Lavc56.60.100 libx264
  
      Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, fltp, 128 kb/s (default)
  
      Metadata:
  
        encoder         : Lavc56.60.100 aac
  
  Stream mapping:
  
    Stream #0:0 (h264) -> setpts
  
    Stream #0:1 (aac) -> amix:input0
  
    Stream #1:0 (h264) -> setpts
  
    Stream #1:1 (aac) -> adelay
  
    overlay -> Stream #0:0 (libx264)
  
    amix -> Stream #0:1 (aac)
  
  Press [q] to stop, [?] for help
  
  [Parsed_overlay_2 @ 0x169afe0] [framesync @ 0x169b128] Buffer queue overflow, dropping.
  
      Last message repeated 1 times
  
  [Parsed_overlay_2 @ 0x169afe0] [framesync @ 0x169b128] Buffer queue overflow, dropping.
  
      Last message repeated 13 times
  
  [Parsed_overlay_2 @ 0x169afe0] [framesync @ 0x169b128] Buffer queue overflow, dropping