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• FFMPEG stereo track stops capturing at random times during a capture session

  26 mai 2022, par mrwassen

  I am currently working on building a workflow to capture and archive a large stash of family and friends PAL and NTSC VHS tapes. The hardware setup is as follows :

  


  

  • JVC HR-7860S VCR

  


  • s-video / RCA audio >

  


  • ADVC-3000 converter

  


  • SDI / BNC cable >

  


  • Blackmagic Decklink Mini Recorder 4K PCIe card

  


  • installed in a fairly hi-spec windows machine : AMD Ryzen 9 5900X 3.7 Ghz base 12 core, GEFORCE RTX 3060 12 gB, 32 gB ram

  


  


  The plan is to capture to lossless AVI, then drop into an NLE (Vegas Pro v.16) to do a minimal amount of cleanup / trimming, then render to a more compressed video format (TBD) for upload to AWS S3 accessible through a family website.

  


  The issue I am having is that when I run the capture using ffmpeg/directshow e.g. for a perfectly fine 90 min. PAL tape, at some random point of time during the capture one of the 2 stereo channels just stops capturing. This has happened with all of the tapes I have tested so far, and it happens at different times during the same video. I have examined the frames surrounding points in time when this happens, and it doesn't correlate to any transitions or jitter, but often just randomly in the middle of a perfectly smooth scene. Once the one channel stops capturing it never starts back up again during that capture session.

  


  The ADVC-3000 and the VCR are both showing both stereo channels playing normally throughout the capture. The windows machine running the capture hardly breaks a sweat at any time, and the transfer easily keeps up constantly showing a speed = 1x which I assume means nothing lagging. Also there are no video/audio sync issues at any point in time even towards the end of long tapes e.g. 90 mins.

  


  I am fairly new at ffmpeg, so I have spent extensive amounts of time reading up on forum posts and experimenting and have ended up with the following syntax :

  


  ffmpeg -y -f dshow -rtbufsize 2000M -i video="Blackmagic WDM Capture":audio="Blackmagic WDM Capture" -codec:v v210 -pix_fmt yuv422p -codec:a pcm_s16le -b:a 128k -t 02:00:00 -r 25 -threads 4 -maxrate 2500k -filter:a "volume=1.5" output_v210_audio.avi


  


  The capture runs without a single dropped frame, the only error I am getting when launching (and perhaps this is a smoking gun ?) is :

  


  


  "Non-monotonous DTS in output stream 0:1 ; previous : 0, current : -30 ;
changing to 1. This may result in incorrect timestamps in the output
file."

  


  


  I have tried to troubleshoot this in the hopes that it is tied to my issue but so far without luck.

  


  Hoping somebody can help correct or modify my command line or perhaps other ideas to help resolve the issue.

  


• Running "FFMPEG" for several times in winfoms

  13 novembre 2015, par Ahmad

  In a C# Windows application, I try to call "ffmpeg" to multiplex video and audio. It may be called several times. In the first call, everything is fine, but in the next call I have some problems. One problem is that the earlier "ffmpeg" process isn’t closed. So, I tried to kill it if it exists. but now I got an error for a disposed object in the following code :

     public static void FFMPEG3(string exe_path, string avi_path, string mp3_path, string output_file)
  
      {
  
          const int timeout = 2000;
  
          Kill(exe_path);
  
          using (Process process = new Process())
  
          {
  
              process.StartInfo.FileName = exe_path;
  
              process.StartInfo.Arguments = string.Format(@"-i ""{0}"" -i ""{1}"" -acodec copy -vcodec copy ""{2}""",
  
                                             avi_path, mp3_path, output_file);
  
              process.StartInfo.UseShellExecute = false;
  
              process.StartInfo.CreateNoWindow = true;
  
              process.StartInfo.RedirectStandardOutput = true;
  
              process.StartInfo.RedirectStandardError = true;
  
  
  
              StringBuilder output = new StringBuilder();
  
              StringBuilder error = new StringBuilder();
  
  
  
              using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
  
              using (AutoResetEvent errorWaitHandle = new AutoResetEvent(false))
  
              {
  
                  process.OutputDataReceived += (sender, e) =>
  
                  {
  
                      if (e.Data == null)
  
                      {
  
                          outputWaitHandle.Set();
  
                      }
  
                      else
  
                      {
  
                          output.AppendLine(e.Data);
  
                      }
  
                  };
  
                  process.ErrorDataReceived += (sender, e) =>
  
                  {
  
                      if (e.Data == null)
  
                      {
  
                          errorWaitHandle.Set();
  
                      }
  
                      else
  
                      {
  
                          error.AppendLine(e.Data);
  
                      }
  
                  };
  
  
  
                  process.Start();
  
  
  
                  process.BeginOutputReadLine();
  
                  process.BeginErrorReadLine();
  
  
  
                  if (process.WaitForExit(timeout) &&
  
                      outputWaitHandle.WaitOne(timeout) &&
  
                      errorWaitHandle.WaitOne(timeout))
  
                  {
  
                      // Process completed. Check process.ExitCode here.
  
                      process.Close();
  
                  }
  
                  else
  
                  {
  
                      // Timed out.
  
                      process.Close();
  
                  }
  
              }
  
          }
  
      }

  I get ObjectDisposedException for ErrorDataRecieved event on errorWaitHandle.Set();

  First, I want to resolve this error, but if you know any better solution to run the "ffmpeg" for several times please suggest me.

• Scheduled ffmpeg function gives thread.error and also fires ffmpeg too many times

  16 février 2016, par user2192778

  I want to record a clip of a radio stream every hour. Below is the code I am using to accomplish this so far.

      def sched(): # schedules a recording every hour
  
          def stream_record ():
  
              timeinfo = datetime.now().strftime('%Y%m%d_%H%M_%S%f')
  
              ffmpegEXE = "C:/path/to/ffmpeg.exe" 
  
              subprocess.call([ffmpegEXE, '-i', url, '-t', '00:07:00', 
  
              output_folder + timeinfo + '_' + str(start_minute) + 'url.mp3'], shell=True)
  
  
  
          i = 0
  
          while True:
  
  
  
          x = datetime.today()
  
          y=x.replace(day=x.day+1, hour=i, minute= start_minute, second=0, microsecond=0) 
  
          i = (i + 1) % 24
  
          delta_t=y-x
  
          secs=delta_t.seconds+1
  
          t = Timer(secs,stream_record)
  
          t.start()
  
  
  
  sched()

  Two things go wrong. (1) It will run, however an error reads :

  line X in (module)

  sched()

  line Y in sched

  t.start()

  line Z in start

  _start_new_thread(self.__bootstrap, ())

  thread.error : can’t start new thread

  And (2) when it runs, ffmpeg will initialize a recording anywhere from 5-15 times, saving many clips when I only want it to save one.

  How do I fix these errors and get ffmpeg to connect and record only one clip every hour ?

  I know this is an issue with the scheduling function ; the ffmpeg command works fine, as does the python script calling it.