Recherche avancée

Sur d’autres sites (5981)

• Running an FFprobe process in Xcode to return file duration data

  24 octobre 2019, par NCrusher

  Using this example, I was able to create a process to run ffmpeg from the main resource bundle of a MacOS app. The fact that I was able to get it to work, however, was really dumb luck.

  But now I need to be able to do something similar with ffprobe, along the lines of what is discussed in this post, to get the duration of an audio file in order to trim a set number of seconds off the end of it, using these arguments :

  ffprobe -v 0 -show_entries format=duration -of compact=p=0:nk=1 input.m4b

  But I don’t know how to implement it. This is basically what I want to accomplish :

      func insertTrimArguments() {
  
          conversionSelection()
  
          if trimStartEndClipsCheckbox.state == .on {
  
              ffmpegArguments.insert(contentsOf: ["-ss", "00:00:02.000", /*"-t", "duration minus 4.2secs"]*/, at: 3)
  
          }
  
          else {
  
          }
  
      }

  I haven’t been coding in Swift long and processes are entirely new for me and not something that was ever covered in any of the "fundamentals" tutorials I studied before I began my project. Taking the monkey-see/monkey-do approach from the first example I linked, I can sort of make a start imitating it for my ffprobe function, but I have no idea if I’m doing it right or where to go with it from here.

  This is all I have so far.

      // get file duration and subtract 4.2 seconds if "trim audible clips is enabled, then insert additional arguments into conversionSelection arrays
  
      func getFileDuration() {
  
          guard let ffprobePath = Bundle.main.path(forResource: "ffprobe", ofType: "") else { return }
  
          do {
  
              let ffprobeTask: Process = Process()
  
              ffprobeTask.launchPath = ffprobePath
  
              ffprobeTask.arguments = [
  
                  "-v", "error",
  
                  "-show_entries",
  
                  "format=duration", "-of",
  
                  "compact=p=0:nk=1",
  
                  "\(inputFilePath)"]
  
              ffprobeTask.standardInput = FileHandle.nullDevice
  
              ffprobeTask.launch()
  
              ffprobeTask.waitUntilExit()
  
          }
  
      }

  How do I adapt this process so that instead of converting and outputing a new file, it returning the duration of the input file so that I can do the necessary math and include it in my arguments ?

• fftools/ffmpeg_mux_init : only process -enc_time_base if the stream is encoded

  28 mai 2023, par Anton Khirnov

  fftools/ffmpeg_mux_init : only process -enc_time_base if the stream is encoded
  It has no effect otherwise.
  

  • [DH] fftools/ffmpeg_mux_init.c

• .NET Process - Redirect stdin and stdout without causing deadlock

  21 juillet 2017, par user1150856

  I’m trying to encode a video file with FFmpeg from frames generated by my program and then redirect the output of FFmpeg back to my program to avoid having an intermediate video file.

  However, I’ve run into what seems to be a rather common problem when redirecting outputs in System.Diagnostic.Process, mentioned in the remarks of the documentation here, which is that it causes a deadlock if run synchronously.

  After tearing my hair out over this for a day, and trying several proposed solutions found online, I still cannot find a way to make it work. I get some data out, but the process always freezes before it finishes.

  ---

  Here is a code snippet that produces said problem :

  static void Main(string[] args)
  
      {
  
  
  
          Process proc = new Process();
  
  
  
          proc.StartInfo.FileName = @"ffmpeg.exe";
  
          proc.StartInfo.Arguments = String.Format("-f rawvideo -vcodec rawvideo -s {0}x{1} -pix_fmt rgb24 -r {2} -i - -an -codec:v libx264 -preset veryfast -f mp4 -movflags frag_keyframe+empty_moov -",
  
              16, 9, 30);
  
          proc.StartInfo.UseShellExecute = false;
  
          proc.StartInfo.RedirectStandardInput = true;
  
          proc.StartInfo.RedirectStandardOutput = true;
  
  
  
          FileStream fs = new FileStream(@"out.mp4", FileMode.Create, FileAccess.Write);
  
  
  
          //read output asynchronously
  
          using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
  
          {
  
              proc.OutputDataReceived += (sender, e) =>
  
              {
  
                  if (e.Data == null)
  
                  {
  
                      outputWaitHandle.Set();
  
                  }
  
                  else
  
                  {
  
                      string str = e.Data;
  
                      byte[] bytes = new byte[str.Length * sizeof(char)];
  
                      System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
  
                      fs.Write(bytes, 0, bytes.Length);
  
                  }
  
              };
  
          }
  
  
  
  
  
          proc.Start();
  
          proc.BeginOutputReadLine();
  
  
  
          //Generate frames and write to stdin
  
          for (int i = 0; i < 30*60*60; i++)
  
          {
  
              byte[] myArray = Enumerable.Repeat((byte)Math.Min(i,255), 9*16*3).ToArray();
  
              proc.StandardInput.BaseStream.Write(myArray, 0, myArray.Length);
  
          }
  
  
  
          proc.WaitForExit();
  
          fs.Close();
  
          Console.WriteLine("Done!");
  
          Console.ReadKey();
  
  
  
      }

  Currently i’m trying to write the output to a file anyway for debugging purposes, but this is not how the data will eventually be used.

  If anyone knows a solution it would be very much appreciated.