Newest 'ffmpeg' Questions - Stack Overflow

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• Check if a video file has subtitles [closed]

  18 mai, par TRS

  Is it possible to check if a video file has a subtitle using bash and get a simple answer like "yes" or "no". I don't need to know any details about the subtitles.

  Maybe using ffmpeg?

• Increase volume on multiple files

  17 mai, par Reckless Velociraptor

  Let say I have a couple of hundreds mp3 files. How do I increase volume in all of them with ffmpeg?

  This is for single file:

  ffmpeg -i input.mp3 -filter:a "volume=1.5" output.mp3
  

  And what about multiple files with one command?

• Black screen when recording specific screen / window using ffmpeg [closed]

  16 mai, par Mark Brin

  Issue: I'm trying to capture the specific window using ffmpeg & i've tried these below command for that:

  ffmpeg -f gdigrab -framerate 30 -i title="Window Title" -b:v 3M -pix_fmt yuv420p output_FILENAME.webm
  

  And also try changing output format to .mp4

  ffmpeg -f gdigrab -framerate 30 -i title="Window Title" -b:v 3M -pix_fmt yuv420p output_FILENAME.mp4
  

  but the output video just shows the black screen with cursor.

  What i've tried:

  • Tried online solutions like Recording Screen with FFmpeg, How to record a specific window using ffmpeg?, Record specific window using ffmpeg, but none of them worked.

  • even tried some of the tweaks like removing flags like -pix_fmt yuv420p also tried -f d3d11grab but didn't work.

  • When i try desktop capture it works completely fine.

  • I'm using this command to confirm that i'm using correct window title

  Get-Process |
    Where-Object { $_.MainWindowTitle -ne "" } |
    Select-Object -Unique MainWindowTitle
  

  System I'm using:

  Windows 11

• Converting mkv files to mp4 with ffmpeg-python

  16 mai, par myth0s

  I have a lot of .mkv files that I'm trying to convert to .mp4, so I decided to try and program a solution in python. After a few hours, trying to figure out how to copy the subfolders too, I gave up on it and decided to stick with converting individual subfolders, and then copying them over to another directory.

  I've made a simple script, that should convert .mkv files that are in the same folder as the script. However, I keep getting this error:

  FileNotFoundError: [WinError 2] The system cannot find the file specified

  Here's my code:

  import os
  import ffmpeg
  
  start_dir = os.getcwd()
  
  def convert_to_mp4(mkv_file):
      no_extension = str(os.path.splitext(mkv_file))
      with_mp4 = no_extension + ".mp4"
      ffmpeg.input(mkv_file).output(with_mp4).run()
      print("Finished converting {}".format(no_extension))
  
  for path, folder, files in os.walk(start_dir):
      for file in files:
          if file.endswith('.mkv'):
              print("Found file: %s" % file)
              convert_to_mp4(file)
          else:
              pass
  
  

• How to interact with process output ?

  14 mai, par 1ben99

  Ok so at the moment I have a program which runs FFmpeg using a process in VB.net. I send the process arguments in the startinfo as well as other things like the file location. When I run the code it sends the console output to the debug console; this is probably because I have the .UseShellExecute = False and processInfo.RedirectStandardOutput = True

  My question is: How do I make something which can interpret the output? Also with FFmpeg, the process is continuous so the process is always running for the most part and constantly adding more output lines in the debug console.

  The code I am using:

  Dim process As New Process
          Dim processInfo As New ProcessStartInfo
          processInfo.FileName = tempPath
          processInfo.Arguments = ("-r 1/.1 -i " + link + " -c copy " + saveLocation + "\" + streamerName + ".ts")
          processInfo.UseShellExecute = False
          processInfo.WindowStyle = ProcessWindowStyle.Hidden
          processInfo.CreateNoWindow = True
          processInfo.RedirectStandardOutput = True
          process.StartInfo = processInfo
          process.Start()
  

  I tried this with no luck.

  Dim output As String
          Using StreamReader As System.IO.StreamReader = process.StandardOutput
              output = StreamReader.ReadToEnd().ToString
          End Using
  

  Edit: I now have this code:

  Dim process As New Process
          AddHandler process.OutputDataReceived, AddressOf CallbackProcesoAsync
          AddHandler process.ErrorDataReceived, AddressOf ErrorDataReceivedAsync
          Dim processInfo As New ProcessStartInfo
          processInfo.FileName = tempPath
          processInfo.Arguments = ("-r 1/.1 -i " + link + " -c copy " + saveLocation + "\" + streamerName + ".ts")
          processInfo.UseShellExecute = False
          processInfo.WindowStyle = ProcessWindowStyle.Hidden
          processInfo.CreateNoWindow = False
          processInfo.RedirectStandardOutput = True
          processInfo.RedirectStandardError = True
          process.StartInfo = processInfo
          process.Start()
          processes.Add(Tuple.Create(tempPath, streamerName))
          Debug.WriteLine("Attempting to record " + streamerName)
          Dim output As String
          Using StreamReader As System.IO.StreamReader = process.StandardOutput
              output = StreamReader.ReadToEnd().ToString
          End Using
      End If
  End Sub
  
  Private Sub CallbackProcesoAsync(sender As Object, args As System.Diagnostics.DataReceivedEventArgs)
      If Not args.Data Is Nothing AndAlso Not String.IsNullOrEmpty(args.Data) Then
          RichTextBox1.Text = args.Data
      End If
  End Sub
  
  Private Sub ErrorDataReceivedAsync(sender As Object, args As System.Diagnostics.DataReceivedEventArgs)
      If Not args.Data Is Nothing AndAlso Not String.IsNullOrEmpty(args.Data) Then
          RichTextBox2.Text = args.Data
      End If
  End Sub
  

  But I have not recieved any outputs to the richtextboxes?

  I feel like it has something to do with the streamReader so I removed it and it still didn't work? I don't have any more ideas what it could be.