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• Is there a document or page describing the output of ffprobe -show_frames ?

  4 novembre 2017, par yang

  I am trying to use scene detection filter and extract key frames.

  ffprobe -v quiet -show_frames -of compact=p=0 -f lavfi "movie=sample.mp4,select='gt(scene,.5)'"

  However, the output is really hard to read for me.

  media_type=video|stream_index=0|key_frame=1|pkt_pts=4879872|pkt_pts_time=317.700000|pkt_dts=4879872|pkt_dts_time=317.700000|best_effort_timestamp=4879872|best_effort_timestamp_time=317.700000|pkt_duration=N/A|pkt_duration_time=N/A|pkt_pos=16582154|pkt_size=691200|width=640|height=360|pix_fmt=rgb24|sample_aspect_ratio=1:1|pict_type=I|coded_picture_number=0|display_picture_number=0|interlaced_frame=0|top_field_first=0|repeat_pict=0|tag:lavfi.scene_score=0.548330

  I searched google and here, couldn’t find a document that explain each result. Like what is pkt_pts ? what does best_effort_timestamp mean ? Is there a place to learn all these outputs ?

• JavaFX MediaPlayer unable to play local m3u8 file

  3 mai 2017, par Lennart

  I want to show a live stream of a web cam in my JavaFX application using the MediaPlayer/MediaView. My attempt was to use ffmpeg to record a HLS and to play the resulting m3u8 file, but that throws the following exception (VLC plays the video without problems) :

  MediaException: UNKNOWN : com.sun.media.jfxmedia.MediaException: Could not create player! : com.sun.media.jfxmedia.MediaException: Could not create player!
  
      at javafx.scene.media.MediaException.exceptionToMediaException(MediaException.java:146)
  
      at javafx.scene.media.MediaPlayer.init(MediaPlayer.java:511)
  
      at javafx.scene.media.MediaPlayer.<init>(MediaPlayer.java:414)
  
      at de.fraunhofer.iosb.ias.flow.assessment.management.monitor.MonitorViewController.testStream(MonitorViewController.java:203)
  
      ... 58 more
  
  Caused by: com.sun.media.jfxmedia.MediaException: Could not create player!
  
      at com.sun.media.jfxmediaimpl.NativeMediaManager.getPlayer(NativeMediaManager.java:274)
  
      at com.sun.media.jfxmedia.MediaManager.getPlayer(MediaManager.java:118)
  
      at javafx.scene.media.MediaPlayer.init(MediaPlayer.java:467)
  
      ... 60 more
  
  </init>

  I debugged the player creation and the error occurs inside the constructor of GSTMediaPlayer when GSTMediaPlayer.gstInitPlayer() is called. This native method returns the error code 257, which javafx maps to MediaError.ERROR_MEDIA_NULL.

  I used the following ffmpeg command to record the video :

  ffmpeg -hide_banner -y -rtbufsize 250MB -f dshow -pixel_format yuv420p -video_size 960x720 -i video="Logitech HD Pro Webcam C920" -c:v libx264 -crf 20 -pix_fmt yuv420p out.m3u8

  I’m pretty sure that the encoding matches the requirements of javafx, because if I change the output container from m3u8 to mp4, the video is played without problems using the exact same ffmpeg command.

  This is the output of ffprobe for the m3u8 file :

  Input #0, hls,applehttp, from 'out.m3u8':
  
    Duration: 00:00:24.23, start: 1.466667, bitrate: 0 kb/s
  
    Program 0
  
      Metadata:
  
        variant_bitrate : 0
  
      Stream #0:0: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 960x720, 30 fps, 30 tbr, 90k tbn, 60 tbc

  And for the mp4 file :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'out.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf57.41.100
  
    Duration: 00:01:04.93, start: 0.000000, bitrate: 1676 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 960x720, 1673 kb/s, 30 fps, 30 tbr, 10000k tbn, 60 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler

  The resulting m3u8 file looks like this :

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-TARGETDURATION:9
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXTINF:8.333322,
  
  out0.ts
  
  #EXTINF:8.333333,
  
  out1.ts
  
  #EXTINF:7.133322,
  
  out2.ts
  
  #EXTINF:0.433333,
  
  out3.ts
  
  #EXT-X-ENDLIST

  Update : After I found this reference m3u file, I think that the problem is that the file is stored locally and isn’t delivered via HTTP. The video plays fine with this :

  Media media = new Media("http://download.oracle.com/otndocs/products/javafx/JavaRap/prog_index.m3u8");
  
  MediaPlayer player = new MediaPlayer(media);
  
  player.setAutoPlay(true);
  
  mediaView.setMediaPlayer(player);

  But after I downloaded the reference m3u and all of its segments and tried to open the local file like this, the error occurred again :

  File video = new File("H://Projects//Tools//ref//prog_index.m3u8");
  
  Media media = new Media(video.toURI().toString());
  
  MediaPlayer player = new MediaPlayer(media);
  
  player.setAutoPlay(true);
  
  mediaView.setMediaPlayer(player);

  I tried to change my m3u file so that the segements are referenced with absolute paths. I tried different notations (H:\f\out0.ts, H:/f/out0.ts, H://f//out0.ts, file:/H:/f/out0.ts, file:///H:/f/out0.ts), but I couldn’t get it to work.

• c# Process Arguments and Missing Output

  8 décembre 2017, par Tawm

  I’m using an FFMPEG Process to gather some information on a file :

  private void GatherFrames()
  
  {
  
      Process process = new Process();
  
      process.StartInfo.FileName = "ffmpeg";
  
      process.StartInfo.Arguments = "-i \"" + filePath + "\"";
  
      process.StartInfo.RedirectStandardError = true;
  
      process.StartInfo.UseShellExecute = false;
  
  
  
      if (!process.Start())
  
      {
  
          Console.WriteLine("Error starting");
  
          return;
  
      }
  
      StreamReader reader = process.StandardError;
  
      string line;
  
      while ((line = reader.ReadLine()) != null)
  
      {
  
          outputRichTextBox.AppendText(line + "\n");
  
      }
  
      process.Close();
  
  }

  This seems to works fine. Now I want to get just the FrameRate, and thanks to other posts, I’ve found that ffprobe can be used to do just that :

  public void GetFrameRate()
  
  {
  
      Process process = new Process();
  
      process.StartInfo.FileName = "ffprobe";
  
      process.StartInfo.Arguments = "-v 0 -of compact=p=0 -select_streams 0 -show_entries stream = r_frame_rate \"" + filePath + "\"";
  
      Console.WriteLine(process.StartInfo.Arguments);
  
      process.StartInfo.RedirectStandardError = true;
  
      process.StartInfo.RedirectStandardOutput = true;
  
      process.StartInfo.UseShellExecute = false;
  
      process.StartInfo.CreateNoWindow = false;
  
      Console.WriteLine(process.StartInfo);
  
  
  
      if (!process.Start())
  
      {
  
          Console.WriteLine("Error starting");
  
          return;
  
      }
  
  
  
      StreamReader reader = process.StandardError;
  
      string line;
  
      while ((line = reader.ReadLine()) != null)
  
      {
  
          Console.WriteLine(line);
  
      }
  
      process.Close();
  
  }

  This does not seem to work at all. The process starts, but does not return what I expect to be returned.

  If I run the command manually, I do the following in cmd.exe :

  > e:
  
  > cd "FILE_PATH"
  
  > ffprobe -v 0 -of compact=p=0 -select_streams 0 -show_entries stream=r_frame_rate "FILE_NAME.mp4"
  
  r_frame_rate=60/1

  Note : -show_entries stream = r_frame_rate does not work, only -show_entries stream=r_frame_rate without the spaces.

  ---

  I’m not sure how to properly go about doing this with a Process.