FFMPEG: Recording a video stream to disk real-time

Question

I made a video recording with ffmpeg

 var inputArgs = string.Format(CultureInfo.InvariantCulture, "-framerate {0} -f rawvideo -pix_fmt {3} -video_size {1}x{2} -i -", VideoFPS, VideoXRes, VideoYRes, VideoPXLFormat);

 var outputArgs = string.Format(CultureInfo.InvariantCulture, "-vcodec mpeg4 -crf {2} -pix_fmt yuv420p -preset {3} -shortest -r {1} \"{0}\"", outputPath, VideoFPS, VideoCRFValue, CompressionRate);

 var ffmpegProcess = new Process
        {
            StartInfo =
            {
                FileName = ffmpegPath,
                Arguments = $"{inputArgs} {outputArgs}",
                UseShellExecute = false,
                CreateNoWindow = true,
                RedirectStandardInput = true
            }
        };

        ffmpegProcess .Start();
        var VideoRecordingFFmpegInput = VideoRecordingFFmpegProcces.StandardInput.BaseStream;

Now I write data bytes from the image into the stream from time to time

VideoRecordingFFmpegInput.Write(framesByteArray, 0, sizeOfpack);

When I finished recording the frames:

  VideoRecordingFFmpegInput.Flush();
  VideoRecordingFFmpegInput.Close();
  ffmpegProcess.WaitForExit();

Everything works fine, and it creates the file I want.

When the process starts, it creates a file that has a very small size

And during the recording of image bytes in the video stream - this size does not change (Probably it is written to RAM?)

But as soon as the ffmpeg process finishes - flush / close the file size becomes normal.

The problem is that if I record for several hours it can cause an OutOfMemory exception

Is there any way to have the frames record and immediately increase the file size? (Without infinitely filling RAM?)