Recherche avancée

Sur d’autres sites (4599)

• Process is not exiting ffmpeg.exe only for the command which detects the silences from a video

  20 juillet 2015, par Jitender Kumar

  The job of the method ExecuteCommandSync is to detect the silences from a video and return the output as string but when I run this code it never bring the value of proc.HasExited as true. If I forcefully drag the debugger to the line

  result =proc.StandardOutput.ReadToEnd()

  then it never exit the ffmpeg.exe so as a result control never returns back.

  Although the same method is working fine for a different command like creating an audio file from a video. In this case proc.HasExited also returns false but it also generates the audio file successfully.

  public static string ExecuteCommandSync(string fileName, int timeoutMilliseconds)
  
      {
  
          string result = String.Empty;
  
          string workingDirectory = Directory.GetCurrentDirectory();
  
          try
  
          {
  
              string command = string.Format("ffmpeg -i {0} -af silencedetect=noise=-20dB:d=0.2 -f null -", "\"" + fileName + "\"");                
  
              System.Diagnostics.ProcessStartInfo procStartInfo =
  
                  new System.Diagnostics.ProcessStartInfo("cmd", "/c " + command);
  
  
  
              procStartInfo.WorkingDirectory = workingDirectory;                
  
              procStartInfo.RedirectStandardOutput = true;
  
              procStartInfo.RedirectStandardError = true;
  
              procStartInfo.UseShellExecute = false;                
  
              procStartInfo.CreateNoWindow = false;                
  
              System.Diagnostics.Process proc = new System.Diagnostics.Process();
  
              proc.StartInfo = procStartInfo;
  
              proc.Start();                
  
              proc.WaitForExit(timeoutMilliseconds);
  
              // Get the output into a string 
  
              if (proc.HasExited)
  
              {
  
                  if (!proc.StandardOutput.EndOfStream)
  
                  {
  
                      result = proc.StandardOutput.ReadToEnd();
  
                  }
  
                  else if (!proc.StandardError.EndOfStream)
  
                  {
  
                      result = "Error:: " + proc.StandardError.ReadToEnd();
  
                  }
  
              }
  
          }
  
          catch (Exception)
  
          {
  
              throw;
  
          }
  
          return result;
  
      }

  So please advice.

• Transfer audio with ffmpeg, unexpected silent at the beginning [duplicate]

  4 mai 2018, par LouisCJT

  This question already has an answer here :

  • ffmpeg wrong audio file after conversion in AAC
    
    1 answer
    
  • Why does libmp3lame add zeros to the start of the MP3 ?
    
    1 answer
    

  I was using ffmpeg to transfer the format of audio files, like from .wav to mp3. The transfer seemed fine and the audio sounds as expected. However when I check its waveform, I found that after the transfer,

  1. A small portion of silent (and with some very tiny noise) is at the beginning of the output audio. The length is about 1 ms 0.001 sec.

  2. As the silent part is appended, the end of the audio is altered - the length of the output audio is longer than the input file. (my input is exactly 10 sec, now the output is around 10.1 sec.

  Need the transfer precise because need to do further analysis frame by frame, and this situation could not go well. I used the following command to transfer a file.

  ffmpeg -I ..\wav_1K_32bit_24576kbps_384000Hz_stereo.wav -vn -ar 12000 -ac 2 -ab 320000 -f MP3 MP3_12000Hz_32kbps_stereo_VBROff.MP3

  ---

  Please refer to the screen crop of waveform view.

  Beginning of audio, input (U) & output (L)

  End of audio, input (U) & output (L)

  Thank you !

• libfdk-aacdec : Reduce the default decoder delay by one frame

  4 juillet 2014, par Omer Osman

  libfdk-aacdec : Reduce the default decoder delay by one frame
  The default error concealment method if none is set via
  
  aacDecoder_SetParam(AAC_CONCEAL_METHOD) is set in
  
  CConcealment_InitCommonData within the fdk-aac library
  
  and is set to Energy Interpolation. This method requires one frame
  
  delay to the output. To reduce the default decoder output delay and
  
  avoid missing the last frame in file based decoding, use Noise
  
  Substitution as the default concealment method.
  Signed-off-by : Omer Osman <omer.osman@iis.fraunhofer.de>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavcodec/libfdk-aacdec.c
  • [DBH] libavcodec/version.h