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• How to properly pipe adb screenrecord (h264 stream) to ffplay in a WinForms app ?

  23 avril 2022, par GeneralFuzz

  How to pipe ADB's exec out to ffplay ?

  


  I have been struggling to get this "Live view" C# WinForms app working properly this last week. The goal is to have the android screen in the native app window where I then have other controls implemented as an overlay.

  


  I am able to live stream by piping adb's screen record H264 into FFplay via CMD.
A CMD process that launches a .BAT does function, but I can't manipulate FFplay as control seems to be lost with how it's launched (Correct if wrong).
I just need a programmatic version of this where I can then control the FFplay window to merge it as a child into my form.

  


  adb exec-out screenrecord --output-format=h264 - | ffplay -window_title "Live View" -framerate 60 -framedrop -probesize 32 -sync video  -


  


  I also attempted creating a ADB and FFplay process, manually trying to write the standard in from ADB's standard out. The standard out was received but I couldn't figure out writing to ffplay correctly. May have had a same thread deadlock issue.

  


          //Configure ffplay process and start
        //ffplayProcess.SynchronizingObject();
        ffplayProcess.OutputDataReceived += (o, ev) => Debug.WriteLine(ev.Data ?? "NULL", "ffplay");
        ffplayProcess.ErrorDataReceived += (o, ev) => Debug.WriteLine(ev.Data ?? "NULL", "ffplay");
        ffplayProcess.Exited += (o, ev) => Debug.WriteLine("Exited", "ffplay");
        try
        {
            ffplayProcess.Start();
        }
        catch (Exception err)
        {
            MessageBox.Show($"Failed to start livestream. {err.Message}", "Live Stream Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            return;
        }

        //Wait/check the process started, then...
        System.Threading.Thread.Sleep(200);

        //Run only if ffplay has not exited
        if (ffplayProcess.HasExited == false)
        {
            // make 'this' the parent of ffmpeg (presuming you are in scope of a Form or Control)
            SetParent(ffplayProcess.MainWindowHandle, this.Handle);
            MoveWindow(ffplayProcess.MainWindowHandle, 0, 0, 240, 320, true);
        }

        adbProcess.OutputDataReceived += (o, ev) => {
            Debug.WriteLine(ev.Data ?? "NULL", "adb");

            if (ev.Data != "NULL" || ev.Data != null)
            {
                //Convert data to byte array
                //byte[] dataBytes = Encoding.ASCII.GetBytes(ev.Data);
                byte[] dataBytes = Encoding.UTF8.GetBytes(ev.Data);
                ffplayProcess.StandardInput.BaseStream.WriteAsync(dataBytes, 0, dataBytes.Length);
                ffplayProcess.StandardInput.BaseStream.FlushAsync();
            }
        };
        adbProcess.ErrorDataReceived += (o, ev) => Debug.WriteLine(ev.Data ?? "NULL", "adb");
        adbProcess.Exited += (o, ev) => Debug.WriteLine("Exited", "adb");

        adbProcess.Start();

        adbProcess.BeginOutputReadLine();
        adbProcess.BeginErrorReadLine();


  


  My current attempt is using MedallionShell to pipe into the FFplay process. ADB and FFPlay launch, but I never get FFplay's video out window.

  


  private void FormLiveView_Load(object sender, EventArgs e)
{
        var command = Medallion.Shell.Command.Run(tmpPath + "/adb.exe", new[] { "exec-out screenrecord --output-format=h264 -" }, options => { options.DisposeOnExit(false); });
            
        command.PipeTo(Medallion.Shell.Command.Run(tmpPath + "/ffplay.exe", new[] { "-framerate 60 -framedrop -probesize 32 -sync video -" }, options => { options.DisposeOnExit(false); }));
}


  


• How to implement Seekbar for a video player playing FFmpeg pipe output in Flutter ?

  19 avril 2022, par Lins Louis

  I was about to create a video player that can play FFmpeg pipe output in flutter. Luckily i found a solution with Github project flutter-ffmpeg, Thanks @tanersener for this amazing project https://github.com/tanersener/flutter-ffmpeg

  


  Below I am mentioning the comment that helped me to achieve the feature i was looking for

  


  https://github.com/tanersener/flutter-ffmpeg/issues/92#issuecomment-606051974

  


  thanks, @reeckset also.

  


  BTW, my current issue is, that I didn't find any solution on how to seek my video player that plays a pipe output of ffmpeg. Is there anything I can do for implementing a Seekbar in my video player

  


• Receiving multiple files from ffmpeg via subprocesses.PIPE

  11 avril 2022, par Per Plexi

  I am using ffmpeg to convert a video into images. These images are then processed by my Python program. Originally I used ffmpeg to first save the images to disk, then reading them one by one with Python.

  



  This works fine, but in an effort to speed up the program I am trying to skip the storage step and only work with the images in memory.

  



  I use the following ffmpeg and Python subproccesses command to pipe the output from ffmpeg to Python :

  



  command = "ffmpeg.exe -i ADD\\sg1-original.mp4 -r 1 -f image2pipe pipe:1"
pipe = subprocess.Popen(ffmpeg-command, stdout = subprocess.PIPE, stderr = subprocess.PIPE)
image = Image.new(pipe.communicate()[0])


  



  The image variable can then be used by my program. The problem is that if I send more than 1 image from ffmpeg all the data is stored in this variable. I need a way to separate the images. The only way I can think of is splitting on jpeg markers end of file (0xff, 0xd9). This works, but is unreliable.

  



  What have I missed regarding piping files with subproccesses. Is there a way to only read one file at a time from the pipeline ?