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• With CMD wrong output subprocess with ffmpeg/ffprobe

  21 avril 2021, par Nicolas Maslorz

  i have a problem with ffmpeg when i run it in the cmd i havethe correct output "ffprobe passionfruit.mp4 -show_streams"  

  


  But when i use the same with subprocess :

  


  command = 'ffprobe "C:/Users/NMASLORZ/Downloads/passionfruit.mp4" -show_streams'
p = subprocess.Popen(command, universal_newlines=True, shell=True,stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
text = p.stdout.read()
retcode = p.wait()
print (text)


  


  i have this output :
"'ffprobe' is not recognized as an internal command or external, an executable program or a batch file."
i tried every synthax and even in a list i still have the same output

  


• FFMpeg in C# with streams

  9 juin 2024, par oLaDushek

  I am trying to crop mp3 using FFMpeg. I need to use streams for both input and output data.

  


  At the moment, I'm trying to use the stream at least only for input data.

  


          var inputFile = @"D:\TestInput.mp3";
        
        var process = new Process
        {
            StartInfo = new ProcessStartInfo
            {
                FileName = @"path\to\ffmpeg.exe",
                Arguments = "-i - -vn -acodec copy -ss 00:00:00 -t 00:00:30 -y D:\\TestFFMpeg.mp3",
                RedirectStandardInput = true,
                UseShellExecute = false
            },
            EnableRaisingEvents = true
        };
        
        process.Start();
        
        using (var input = File.OpenRead(inputFile))
        {
            input.CopyTo(process.StandardInput.BaseStream);
        }
        
        process.WaitForExit();


  


  This code generates an error "System.IO.IOException : Channel is closed.", but it performs its task, the output file is created correctly.
At the same time, if I remove the "-to" block from the arguments, it will work

  


• Why subprocess.run() have unexpected behavior in try else block ?

  25 novembre 2023, par Nikita Savenkov

  Trying to make "to mp4" converter function using ffmpeg that is going to convert a file to mp4, delete original file and return True or False for specific conditions.
But I get some unexpected behavior of a subprocess.

  


  Initially I used this construction :

  


  def to_mp4_converter(file):

    input_file = file
    output_file = f"{re.sub(r'\..+$', "", file)}.mp4"

    try:
        subprocess.run(['ffmpeg', '-i', input_file, output_file])
    except subprocess.SubprocessError as e:
        print(f"Subprocess Error: {e}")
        return False
    else:
        try:
            os.remove(path=file)
        except OSError as e:
            print(f"Can't remove {file} file: {e}")
        finally:
            return True


  


  Original file is removed, but output file is half of the expected size and quality of video is low.

  


  But if I place subprocess.run() and os.remove() into separate try else blocks like that :

  


  def to_mp4_converter(file):

    input_file = file
    output_file = f"{re.sub(r'\..+$', "", file)}.mp4"

    try:
        subprocess.run(['ffmpeg', '-i', input_file, output_file])
    except subprocess.SubprocessError as e:
        print(f"Subprocess Error: {e}")
        return False
    else:
        pass

    try:
        os.remove(path=file)
    except OSError as e:
        print(f"Can't remove {file} file: {e}")
    finally:
        return True


  


  Everything works fine.

  


  Isn't subprocess.run() should be a blocking operation, so the else statement in 1st example is unreachable until conversion is done ?