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• Java 1.7 atomic move does not work correctly ?

  22 février 2018, par Ferguson

  have this scenario :
  On a file system have FFmpeg program which streams a video source from a webcam to youtube server. FFmpeg supports text filter where you can specify from which file it can read some static text to be then "overlayed" over video. The problem is if the file not exists or if someone else is writing in this file then the FFmpeg can crash.

  In Java have done this example with StandardCopyOption.ATOMIC_MOVE option :

  import java.io.PrintWriter;
  
  import java.nio.file.Files;
  
  import java.nio.file.Path;
  
  import java.nio.file.Paths;
  
  import java.nio.file.StandardCopyOption;
  
  import java.util.Date;
  
  import java.util.Random;
  
  import java.util.Timer;
  
  import java.util.TimerTask;
  
  
  
  public class FileMover {
  
  
  
      private void runIt() {
  
          Random r = new Random();
  
          Timer timer = new Timer();
  
          timer.schedule(new TimerTask() {
  
              public void run() {
  
  
  
                  try
  
                  {
  
                    PrintWriter writer = new PrintWriter("c:/video/temppodatki.txt", "UTF-8");
  
                    writer.println("Temp: " + ((int)(Math.random() * (40 - 10)) + 10)+ " °C");
  
                    writer.println("Sla: " +  ((int)(Math.random() * (37 - 30)) + 30)+ " PSU");
  
                    writer.close();    
  
  
  
                    //premaknemo fajl..
  
                    Path sourceFile = Paths.get("c:/video/temppodatki.txt");
  
                    Path destinationFile = Paths.get("c:/video/podatki.txt");
  
                    Files.move(sourceFile, destinationFile, StandardCopyOption.ATOMIC_MOVE);
  
                    System.out.println("move.." + new Date().toString());
  
                  }
  
                  catch(Exception ex)
  
                  {
  
  
  
                  }
  
              }
  
          }, 0, 5 * (1000 * 1));
  
      }
  
  
  
      public static void main(String[] args) {
  
          new FileMover().runIt();
  
      }
  
  
  
  }

  this script writes into tmp file and after that it moves to file from which FFmpeg read.
  But the problem stil remain the same because randomly FFmpeg can crash with :

  

  Is there some other approach to take ?

• Video parameters for best web scrolling performance [duplicate]

  22 février 2018, par biven

  This question already has an answer here :

  • how to change keyframe interval in ffmpeg
    
    2 answers
    
  • How to encode (ffmpeg x264) with continuous seek
    
    1 answer
    
  • FFMPEG : How to encode for seekable video at high key frame interval
    
    1 answer
    

  There is web application which provides next workflow. User uploads video -> backend(by using ffmpeg) transform this video for smaller size(320x240) -> web browser plays transformed video. Key feature of this application should be excellent scrolling possibility of video by progress bar. I mean that video should be scrolled as smoothly as possible (without any jumps) when user moves progress bar position back and forward.

  I thought that small size of video helps to provide good scrolling possibility. But that’s incorrect. I have 2 different videos, one scrolling perfect(as I want), second has same resolotion(320x240), but it is scrolling with jumps and breaks.

  By ffprobe I compared both videos and I have next results :

  Video 1(good scrolling) :

  libavutil      56.  7.100 / 56.  7.100
  
    libavcodec     58.  9.100 / 58.  9.100
  
    libavformat    58.  5.100 / 58.  5.100
  
    libavdevice    58.  0.101 / 58.  0.101
  
    libavfilter     7. 11.101 /  7. 11.101
  
    libswscale      5.  0.101 /  5.  0.101
  
    libswresample   3.  0.101 /  3.  0.101
  
    libpostproc    55.  0.100 / 55.  0.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'spacetestSMALL_512kb.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: mp41
  
      creation_time   : 1970-01-01T00:00:00.000000Z
  
      title           : small test video - http://www.archive.org/details/alanoakleysmalltestvideo
  
      encoder         : Lavf51.10.0
  
      comment         : license:  http://www.copyright.gov/
  
    Duration: 00:00:48.32, start: 0.000000, bitrate: 555 kb/s
  
      Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 320x240, 505 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc (default)
  
      Metadata:
  
        creation_time   : 1970-01-01T00:00:00.000000Z
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 45 kb/s (default)
  
      Metadata:
  
        creation_time   : 1970-01-01T00:00:00.000000Z
  
        handler_name    : SoundHandler

  Video 2(bad scrolling) :

  libavutil      56.  7.100 / 56.  7.100
  
    libavcodec     58.  9.100 / 58.  9.100
  
    libavformat    58.  5.100 / 58.  5.100
  
    libavdevice    58.  0.101 / 58.  0.101
  
    libavfilter     7. 11.101 /  7. 11.101
  
    libswscale      5.  0.101 /  5.  0.101
  
    libswresample   3.  0.101 /  3.  0.101
  
    libpostproc    55.  0.100 / 55.  0.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'e10b1c93-5325-4500-ae7c-12ccd0f617bd.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf58.5.100
  
    Duration: 00:00:07.96, start: 0.000000, bitrate: 428 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 320x240 [SAR 4:3 DAR 16:9], 391 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 33 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler

  What is the key parameter of video which provide possibility for good scrolling in web browser ?

• hwcontext : Perform usual initialisation on derived device contexts

  8 octobre 2017, par Mark Thompson

  hwcontext : Perform usual initialisation on derived device contexts
  The initialisation should be common.  For libmfx, it was previously
  
  happening in the derivation function and this moves it out.
  

  • [DBH] libavutil/hwcontext.c
  • [DBH] libavutil/hwcontext_qsv.c