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• ffmpeg - on end function probably not working correctly ?

  19 janvier 2020, par Jul Pod

  got this code to loop through some .mp4 files and create a screenshot of them :

  files.forEach(file => {
  
      console.log(file);
  
      if(!fs.existsSync('img/' + file.replace('.mp4', '.png'))) {
  
  
  
          ffmpeg({ source: 'movies/' + file})
  
          .takeScreenshots({ timemarks: [ '50' ], size: '150x100' }, 'img/', function(err, filenames) {
  
          })
  
          .on('end', function() {      
  
            fs.rename('img/tn.png', 'img/' + file.replace('.mp4', '.png'), function(err) {if (err) console.log('Error: ' + err) }); 
  
            sleep(1000);  
  
        })   
  
        }    
  
  });

  Now i got the problem that it seems like that .on(end) is sometimes not working, Error :
  ENOENT : no such file or directory, rename

  i think it´s because the process of saving the tn.png is slower than the renaming...

• FFMPEG delay mutliple overlay videos (with different delays)

  28 avril 2019, par Bamba675

  I’m trying to overlay a video (for example a report) with different other videos or images, like hints to the facebook page or a hint to the website. These other videos or images are smaller than the original and sometimes transparent (rgba).

  I already tried to overlay multiple videos, which works pretty well :
  

  ffmpeg -i 30fps_fhd.mp4 -i sample.mp4 -i timer.webm -i logo.jpg -filter_complex "overlay = x=100:y=1000, overlay = x=30:y=66:eof_action=pass, overlay = x=0:y=0" -acodec copy -t 70 out.mp4

  But now, I want to start some videos or images not at the beginning of the video, instead after a period of time.
  I found flags like ’itsoffset’ or ’setpts’, but I dont know how to apply them on this ’multiple video / image overlay command’.

  LG Bamba

• using ffmpeg for silence detect with input pipe

  24 août 2018, par Moharrer

  I am trying to detect silence from audio file with ffmpeg in c#.
  i want to pipe input from c# memory stream and get silence duration like following command

  ffmpeg -hide_banner -i pipe:0 -af silencedetect=noise=-50dB:d=0.5 -f null - 

  but there is a problem, when input stream pump in pipe, ffmpeg waiting in p.WaitForExit() line.
  when i change p.WaitForExit() to p.WaitForExit(1000) and set force timeout the following result is displayed.
  

  [mp3 @ 00000163818da580] invalid concatenated file detected - using bitrate for durationInput #0, mp3, from ’pipe:0’ :  
  Metadata :    encoder : Lavf57.71.100  Duration : N/A, start : 0.023021, bitrate : 86 kb/s    
  Stream #0:0 : Audio : mp3, 48000 Hz, mono, fltp, 86 kb/sStream mapping :  Stream #0:0 -> #0:0 (mp3 (mp3float) -> pcm_s16le (native))Output #0, null, to ’pipe :’ :  
  Metadata :    encoder : Lavf58.17.101    Stream #0:0 : Audio : pcm_s16le, 48000 Hz, mono, s16, 768 kb/s   
   Metadata :      encoder : Lavc58.21.105 pcm_s16le
  [silencedetect @ 0000023df1786840] silence_start : 50.1098
  
  [silencedetect @ 0000023df1786840] silence_end : 51.5957 | silence_duration : 1.48588
  
  [silencedetect @ 0000023df1786840] silence_start : 51.5959
  
  [silencedetect @ 0000023df1786840] silence_end : 52.127 | silence_duration : 0.531062
  
  [silencedetect @ 0000023df1786840] silence_start : 52.8622
  
  [silencedetect @ 0000023df1786840] silence_end : 54.0096 | silence_duration : 1.14733
  
  [silencedetect @ 0000023df1786840] silence_start : 54.6804
  

  as you can see in result silence detection done but with error at the first.
  this mean input file pumped correctly in ffmpg but waiting.
  how can i solve problem without set time out for p.WaitForExit()

  private void Execute(string exePath, string parameters, Stream inputStream)
          
              byte[] Data = new byte[5000] ;
              var p = new Process() ;
  
              var sti = p.StartInfo ;
  
              sti.CreateNoWindow = true ;
  
              sti.UseShellExecute = false ;
  
              sti.FileName = exePath ;
  
              sti.Arguments = arg ;
  
              sti.LoadUserProfile = false ;
  
              sti.RedirectStandardInput = true ;
  
              sti.RedirectStandardOutput = true ;
              sti.RedirectStandardError = true ;
              p.ErrorDataReceived += P_ErrorDataReceived ;
  
              p.OutputDataReceived += P_OutputDataReceived ;
              p.Start() ;
              p.BeginOutputReadLine() ;
  
              p.BeginErrorReadLine() ;
              var spInput = new StreamPump(inputStream, p.StandardInput.BaseStream, 4064) ;
  
              spInput.Pump((pump, result) =>
  
              
  
                  pump.Output.Flush() ;
  
                  inputStream.Dispose() ;
  
              ) ;
              //unlimited waiting
  
              //p.WaitForExit() ;
              p.WaitForExit(1000) ;