事实上，它是多种技术的组合，但我的问题的答案（我认为）最接近 Direct3D 9。我正在连接任意 D3D9 应用程序，在大多数情况下它是一个游戏，并注入我自己的代码来修改EndScene 函数的行为。后缓冲区被复制到一个表面，该表面设置为指向推送源 DirectShow 过滤器中的位图。过滤器以 25 fps 的速度对位图进行采样，并将视频流式传输到 .avi 文件中。在游戏的屏幕上显示了一个文本叠加层，告诉用户应该停止游戏捕获的热键组合，但这个叠加层不应该出现在录制的视频中。除了一个令人讨厌的事实外，一切都运行得又快又漂亮。在随机的情况下，带有文本的帧过度进入录制的视频。这不是一个真正想要的人工制品，最终用户只想在视频中看到他的游戏玩法，而不是别的。我很想听听是否有人可以分享为什么会发生这种情况的想法。这是 EndScene 挂钩的源代码：
using System;
using SlimDX;
using SlimDX.Direct3D9;
using System.Diagnostics;
using DirectShowLib;
using System.Runtime.InteropServices;
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[System.Security.SuppressUnmanagedCodeSecurity]
[Guid("EA2829B9-F644-4341-B3CF-82FF92FD7C20")]
public interface IScene
{
unsafe int PassMemoryPtr(void* ptr, bool noheaders);
int SetBITMAPINFO([MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)]byte[] ptr, bool noheaders);
}
public class Class1
{
object _lockRenderTarget = new object();
public string StatusMess { get; set; }
Surface _renderTarget;
//points to image bytes
unsafe void* bytesptr;
//used to store headers AND image bytes
byte[] bytes;
IFilterGraph2 ifg2;
ICaptureGraphBuilder2 icgb2;
IBaseFilter push;
IBaseFilter compressor;
IScene scene;
IBaseFilter mux;
IFileSinkFilter sink;
IMediaControl media;
bool NeedRunGraphInit = true;
bool NeedRunGraphClean = true;
DataStream s;
DataRectangle dr;
unsafe int EndSceneHook(IntPtr devicePtr)
{
int hr;
using (Device device = Device.FromPointer(devicePtr))
{
try
{
lock (_lockRenderTarget)
{
bool TimeToGrabFrame = false;
//....
//logic based on elapsed milliseconds deciding if it is time to grab another frame
if (TimeToGrabFrame)
{
//First ensure we have a Surface to render target data into
//called only once
if (_renderTarget == null)
{
//Create offscreen surface to use as copy of render target data
using (SwapChain sc = device.GetSwapChain(0))
{
//Att: created in system memory, not in video memory
_renderTarget = Surface.CreateOffscreenPlain(device, sc.PresentParameters.BackBufferWidth, sc.PresentParameters.BackBufferHeight, sc.PresentParameters.BackBufferFormat, Pool.SystemMemory);
} //end using
} // end if
using (Surface backBuffer = device.GetBackBuffer(0, 0))
{
//The following line is where main action takes place:
//Direct3D 9 back buffer gets copied to Surface _renderTarget,
//which has been connected by references to DirectShow's
//bitmap capture filter
//Inside the filter ( code not shown in this listing) the bitmap is periodically
//scanned to create a streaming video.
device.GetRenderTargetData(backBuffer, _renderTarget);
if (NeedRunGraphInit) //ran only once
{
ifg2 = (IFilterGraph2)new FilterGraph();
icgb2 = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();
icgb2.SetFiltergraph(ifg2);
push = (IBaseFilter) new PushSourceFilter();
scene = (IScene)push;
//this way we get bitmapfile and bitmapinfo headers
//ToStream is slow, but run it only once to get the headers
s = Surface.ToStream(_renderTarget, ImageFileFormat.Bmp);
bytes = new byte[s.Length];
s.Read(bytes, 0, (int)s.Length);
hr = scene.SetBITMAPINFO(bytes, false);
//we just supplied the header to the PushSource
//filter. Let's pass reference to
//just image bytes from LockRectangle
dr = _renderTarget.LockRectangle(LockFlags.None);
s = dr.Data;
Result r = _renderTarget.UnlockRectangle();
bytesptr = s.DataPointer.ToPointer();
hr = scene.PassMemoryPtr(bytesptr, true);
//continue building graph
ifg2.AddFilter(push, "MyPushSource");
icgb2.SetOutputFileName(MediaSubType.Avi, "C:\foo.avi", out mux, out sink);
icgb2.RenderStream(null, null, push, null, mux);
media = (IMediaControl)ifg2;
media.Run();
NeedRunGraphInit = false;
NeedRunGraphClean = true;
StatusMess = "now capturing, press shift-F11 to stop";
} //end if
} // end using backbuffer
} // end if Time to grab frame
} //end lock
} // end try
//It is usually thrown when the user makes game window inactive
//or it is thrown deliberately when time is up, or the user pressed F11 and
//it resulted in stopping a capture.
//If it is thrown for another reason, it is still a good
//idea to stop recording and free the graph
catch (Exception ex)
{
//..
//stop the DirectShow graph and cleanup
} // end catch
//draw overlay
using (SlimDX.Direct3D9.Font font = new SlimDX.Direct3D9.Font(device, new System.Drawing.Font("Times New Roman", 26.0f, FontStyle.Bold)))
{
font.DrawString(null, StatusMess, 20, 100, System.Drawing.Color.FromArgb(255, 255, 255, 255));
}
return device.EndScene().Code;
} // end using device
} //end EndSceneHook