我如何运行NamedPipeServerStream异步

本文关键字：NamedPipeServerStream 异步 运行 何运行 | 更新日期: 2023-09-27 18:15:22

我如何运行NamedPipeServerStream异步?

我没有通过服务器在另一台计算机上使用管道。我只在我的电脑上使用它。这是代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.IO.Pipes;
using System.Runtime.InteropServices;
namespace ScreenVideoRecorder
{
    class Ffmpeg
    {
        NamedPipeServerStream p;
        String pipename = "mytestpipe";
        byte[] b;
        //int i, j;
        System.Diagnostics.Process process;
        public Ffmpeg()
        {
        }
        public void Start(string FileName, int BitmapRate )
        {
            p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
            b = new byte[1920 * 1080 * 3]; // Some buffer for the R, G and B of pixels of an image of size 720p.
            process = new System.Diagnostics.Process();
            process.StartInfo.FileName = @"D:'pipetest'pipetest'ffmpegx86'ffmpeg.exe";
            process.EnableRaisingEvents = false;
            process.StartInfo.WorkingDirectory = @"D:'pipetest'pipetest'ffmpegx86";
            process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i ''.'pipe'mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;
            process.Start();
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = false;
            p.WaitForConnection();
        }

一切正常。问题是当进程启动时，我看到命令提示符窗口并看到窗口中的所有工作。我拿不到表格。我可以在屏幕上拖动/移动命令提示符窗口，但我无法到达表单窗口，例如单击按钮或停止操作。我需要等待它先完成在命令提示符窗口或进程窗口中的工作。

使用下面的代码行，我看到了变量p的属性来检查它是否是异步的，但是我如何将它设置为异步的呢?

p.IsAsync

我试着找一些例子，但它们都是根据两台计算机之间的服务器，我想有安全的东西。

之后，我修改了这一行:

p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte,PipeOptions.Asynchronous);

在末尾添加:PipeOptions。异步

现在，当我运行我的应用程序，我得到异常行:

p.Write(rgbValues, 0, length);
异常:

InvalidOpertionException: Pipe has not connected yet.

这是我的全部代码与所有的变化:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.IO.Pipes;
using System.Runtime.InteropServices;
namespace ScreenVideoRecorder
{
    class Ffmpeg
    {
        NamedPipeServerStream p;
        String pipename = "mytestpipe";
        byte[] b;
        //int i, j;
        System.Diagnostics.Process process;
        IAsyncResult ar;
        public Ffmpeg()
        {
        }
        public void Start(string FileName, int BitmapRate )
        {
            p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte,PipeOptions.Asynchronous);
            b = new byte[1920 * 1080 * 3]; // Some buffer for the R G and B of pixels of an image of size 720p.
            process = new System.Diagnostics.Process();
            process.StartInfo.FileName = @"D:'pipetest'pipetest'ffmpegx86'ffmpeg.exe";
            process.EnableRaisingEvents = false;
            process.StartInfo.WorkingDirectory = @"D:'pipetest'pipetest'ffmpegx86";
            process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i ''.'pipe'mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;
            process.Start();
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = false;
            ar = p.BeginWaitForConnection(EndWait,null);
        }
        void EndWait(IAsyncResult iar)
        {
            var state = ar.AsyncState; //fetch result, mandatory!
        }
        public void PushFrame(Bitmap bmp)
        {
            int length;
            // Lock the bitmap's bits.
            //bmp = new Bitmap(1920, 1080);
            Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
            //Rectangle rect = new Rectangle(0, 0, 1280, 720);
            System.Drawing.Imaging.BitmapData bmpData =
                bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly,
                bmp.PixelFormat);
            int absStride = Math.Abs(bmpData.Stride);
            // Get the address of the first line.
            IntPtr ptr = bmpData.Scan0;
            // Declare an array to hold the bytes of the bitmap.
            //length = 3 * bmp.Width * bmp.Height;
            length = absStride * bmpData.Height;
            byte[] rgbValues = new byte[length];
            //Marshal.Copy(ptr, rgbValues, 0, length);
            int j = bmp.Height - 1;
            for (int i = 0; i < bmp.Height; i++)
            {
                IntPtr pointer = new IntPtr(bmpData.Scan0.ToInt32() + (bmpData.Stride * j));
                System.Runtime.InteropServices.Marshal.Copy(pointer, rgbValues, absStride * (bmp.Height - i - 1), absStride);
                j--;
            }
            p.Write(rgbValues, 0, length);
            bmp.UnlockBits(bmpData);

异常消息:

System.InvalidOperationException was unhandled
  HResult=-2146233079
  Message=Pipe hasn't been connected yet.
  Source=System.Core
  StackTrace:
       at System.IO.Pipes.PipeStream.CheckWriteOperations()
       at System.IO.Pipes.PipeStream.Write(Byte[] buffer, Int32 offset, Int32 count)
       at ScreenVideoRecorder.Ffmpeg.PushFrame(Bitmap bmp) in d:'C-Sharp'ScreenVideoRecorder'ScreenVideoRecorderWorkingVersion'Ffmpeg.cs:line 77
       at ScreenVideoRecorder.Form1.StartRecording_Click(Object sender, EventArgs e) in d:'C-Sharp'ScreenVideoRecorder'ScreenVideoRecorderWorkingVersion'Form1.cs:line 53
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at ScreenVideoRecorder.Program.Main() in d:'C-Sharp'ScreenVideoRecorder'ScreenVideoRecorderWorkingVersion'Program.cs:line 18
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

我如何运行NamedPipeServerStream异步

当您使用NamedPipeServerStream.WaitForConnection时，当前线程将阻塞，直到操作完成。
你可以使用BeginWaitForConnection来创建一个线程，它将在后台工作。通过返回的IAsyncResult，可以获取异步操作的结果。

从MSDN:

IAsyncResult接口是由包含异步操作方法的类实现的。它是发起异步操作的方法的返回类型，比如FileStream.BeginRead，它被传递给结束异步操作的方法，比如FileStream.EndRead。当异步操作完成时，IAsyncResult对象也传递给AsyncCallback委托调用的方法。支持IAsyncResult接口的对象存储异步操作的状态信息，并提供同步对象，以便在操作完成时通知线程。

class Ffmpeg
{
    NamedPipeServerStream p;
    String pipename = "mytestpipe";
    byte[] b;
    //int i, j;
    System.Diagnostics.Process process;
    IAsyncResult ar;
    public Ffmpeg()
    {
    }
    public void Start(string FileName, int BitmapRate )
    {
        p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
        b = new byte[1920 * 1080 * 3]; // some buffer for the r g and b of pixels of an image of size 720p 
        process = new System.Diagnostics.Process();
        process.StartInfo.FileName = @"D:'pipetest'pipetest'ffmpegx86'ffmpeg.exe";
        process.EnableRaisingEvents = false;
        process.StartInfo.WorkingDirectory = @"D:'pipetest'pipetest'ffmpegx86";
        process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i ''.'pipe'mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;
        process.Start();
        process.StartInfo.UseShellExecute = false;
        process.StartInfo.CreateNoWindow = false;
        ar = p.BeginWaitForConnection(EndWait, null);
    }
//callback when client connects
void EndWait(IAsyncResult iar){
    var state = iar.AsyncState; // fetch state -> cast to desired type
    //do something when client connected
}
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