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• Revision 4118 : mini scorie

  3 octobre 2010, par kent1 — Log

  mini scorie

• FFmpeg, framerate changes so my videos gets fast

  30 avril 2017, par John Smith

  Im trying to capture desktop :

  ffmpeg -r 30 -framerate 30 -rtbufsize 1500M -f dshow -i video="screen-capture-recorder":audio="virtual-audio-capturer" -vcodec libx264 -threads 0 -crf 0 -preset ultrafast -tune zerolatency -acodec pcm_s16le output.mkv

  as soon as I start it, I start a game which runs at 50 fps. But when the game runs, capturing becames "fast", so replaying the output.mk4 results fps-desynchronization. Interestingly, FFmpeg say fps at the beginning then it changes to 26 when game runs and when its done, it again jumps to 30. How to enforce constants 30 fps ?

• Is it possible to adjust position of gdigrab recording region during recording ?

  30 novembre 2020, par adelima

  I'm using ffmpeg for recording video from defined desktop region by starting ffmpeg.exe as process with arguments like so :

  


      public static void StartRecording(Video v) {
        string outPath = Path.Combine(Application.StartupPath, "rec", $"{v.FileName}.mkv");
        v.FFMPEG = new Process {
            StartInfo = new ProcessStartInfo() {
                Arguments = $"-hide_banner -y -thread_queue_size 512 -f gdigrab -offset_x {v.Bounds.X} -offset_y {v.Bounds.Y} -video_size {v.Bounds.Width}x{v.Bounds.Height} -show_region 0 -i desktop -vf \"scale=trunc(iw/2)*2:trunc(ih/2)*2\" -c:v libx264 -preset ultrafast -crf 18 -pix_fmt yuv420p \"{outPath}\"",
                WindowStyle = ProcessWindowStyle.Hidden,
                CreateNoWindow = true,
                UseShellExecute = false,
                FileName = Path.Combine(Application.StartupPath, "bin", "ffmpeg.exe"),
                RedirectStandardOutput = true,
                RedirectStandardInput = true,
                RedirectStandardError = true,
            }
        };
        v.FFMPEG.Start();

        new Thread(() => {
            using(StreamReader sr = v.FFMPEG.StandardError) {
                while(!sr.EndOfStream) {
                    Debug.WriteLine(sr.ReadLine());
                }
            }
        }).Start();
    }

    public static void StopRecording(Video v) {
        using(StreamWriter sw = v.FFMPEG.StandardInput) {
            sw.WriteLine("q\n");
        }
        v.FFMPEG.WaitForExit();
        v.FFMPEG.Dispose();
    }


  


  Is it possible to make changes to the -offset_x and -offset_y arguments during recording ? I'm drawing the recording region bounds with directx and want to add a titlebar to it which can be dragged to move the recording region, but I'm not sure how I would let ffmpeg know that I want these offsets changed or whether it's even possible.