Faster way to write image to Process.StandardInput

问题:

Im trying to send a lot of desktop captured images to an encoders (FFmpeg) stdin.

The following code example works.

the CaptureScreen() function provides an image in 5-10 ms.

If I save the image in a MemoryStream it takes almost no time.

But I can only save 1 image every 45 ms to proc.StandardInput.BaseStream.

public void Start(string bitrate, string buffer, string fps, string rtmp, string resolution, string preset)
{
    proc.StartInfo.FileName = myPath + "\\ffmpeg.exe";
    proc.StartInfo.Arguments = "-f image2pipe -i pipe:.bmp -vcodec libx264 -preset " + preset + " -maxrate " + bitrate + "k -bufsize " +
    buffer + "k -bt 10 -r " + fps + " -an -y test.avi"; //+ rtmp;
    proc.StartInfo.UseShellExecute = false;
    proc.StartInfo.RedirectStandardInput = true;
    proc.StartInfo.RedirectStandardOutput = true;

    proc.Start();

    Stopwatch st = new Stopwatch();
    BinaryWriter writer = new BinaryWriter(proc.StandardInput.BaseStream);
    System.Drawing.Image img;

    st.Reset();
    st.Start();

    for (int z = 0; z < 100; z++)
    {
        img = ScrCap.CaptureScreen();
        img.Save(writer.BaseStream, System.Drawing.Imaging.ImageFormat.Bmp);
        img.Dispose();
    }

    st.Stop();
    System.Windows.Forms.MessageBox.Show(st.ElapsedMilliseconds.ToString());
}

The question is:

Can I do the saving process faster?

I try to get stable 60 fps this way

回答1:

The bottleneck here is that ffmpeg reads data at the same speed it compresses it to .avi, which is slow. So your img.Save method blocks until there is some space in the stream's buffer to write its data.

There is not much you can do. Compressing 60 fps HD video in real time require a huge processing power.