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• Problem with streamcopy of a part of av1 video in ffmpeg

  22 avril 2020, par vorrom

  I'm trying to cut part of a video from av1-mp4 file with FFMmpeg command and I want do it withuout recompressing. But there is no result.
I try method with -ss -t or -to parameters with different combinations.

  



  ffmpeg -ss 10 -i D:\in_av1.mp4 -t 5 -vcodec copy -acodec copy D:\out_av1.mp4


  



  -ss from input file get me 15 seconds video from beginning instead 5 seconds from 10

  



  ffmpeg -i D:\in_av1.mp4 -ss 10 -t 5 -vcodec copy -acodec copy D:\out_av1.mp4


  



  this way get 5 seconds audio file without video data.
It seems to me that coder can not find start point for operation.

  



  I make an av1.mp4 example file, you can find it here. https://pixeldrain.com/u/c8fbQgYK I understand that AV1 is new format and have experimental flag while converting with it. But nevertheless FFmpeg carrectly change result when I change -t parameter. If I use

  



  ffmpeg -ss 10 -i D:\in_av1.mp4 -t 7 -vcodec copy -acodec copy D:\out_av1.mp4


  



  it give me 17 seconds. So -t part working. Whats why I hope there is way to solve my problem.

  



  I use ffmpeg-20200417-889ad93-win64-static for Windows.

  


• configure+libm.h : add hypot emulation

  14 novembre 2015, par Ganesh Ajjanagadde

  configure+libm.h : add hypot emulation
  It is known that the naive sqrt(x*x + y*y) approach for computing the
  
  hypotenuse suffers from overflow and accuracy issues, see e.g
  
  http://www.johndcook.com/blog/2010/06/02/whats-so-hard-about-finding-a-hypotenuse/.
  
  This adds hypot support to FFmpeg, a C99 function.
  On platforms without hypot, this patch does a reaonable workaround, that
  
  although not as accurate as GNU libm, is readable and does not suffer
  
  from the overflow issue. Improvements can be made separately.
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  

  • [DH] configure
  • [DH] libavutil/libm.h

• Error using javacv library for live streaming camera to server

  22 juin 2015, par Prathyush Kumar

  I am new to live-streaming i’m following this link
  here for implementing camera streaming to server with ffserver listening on port 8090.But my code breaks at this line

  public void startRecording() {
  
      try {
  
          recorder.start();    //breaks here
  
          startTime = System.currentTimeMillis();
  
          recording = true;
  
          audioThread.start();
  
      } catch (FFmpegFrameRecorder.Exception e) {
  
          e.printStackTrace();
  
      }
  
  }

  I debugged a little bit to find out what is happening and i found out in this line in FFmpegFrameRecorder.class

  if((this.oformat.flags() & 1) == 0) {
  
      AVIOContext pb1 = new AVIOContext((Pointer)null);
  
      if((ret = avformat.avio_open(pb1, this.filename, 2)) < 0) {//throwing exception here
  
          this.release();
  
          throw new Exception("avio_open error() error " + ret + ": Could not open \'" + this.filename + "\'");
  
      }
  
  
  
      this.oc.pb(pb1);
  
  }

  ret is -5 which is less than 0 and so it cannot open the file(rtmp ://live:live@192.168.0.115:8090/live/test.flv).

  I am not able to understand whats happening in avformat.class Please help

  Is this any configuration problem for ffserver or is it anything else ?I’m not able to figure this out please any help would be greatly appreciated.