Hello,
I use DirectShow in C# application to create a graph containing a camera (Camera-M) connected to SampleGrabber. I used GraphEdit to generate an example that I copied into my app.
But this code does not run correctly and produces an error: "Building graph ...
Camera-M can not connect and SampleGrabber", at the connection of the two filters.
I send you the code used by GraphEdit product.
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices.ComTypes;
using System.Runtime.InteropServices;
using DirectShowLib;
namespace PixiGraph
{
public class Graph
{
public Graph()
{
IGraphBuilder graph = (IGraphBuilder)new FilterGraph();
Console.WriteLine("Building graph...");
BuildGraph(graph);
}
static void BuildGraph(IGraphBuilder pGraph)
{
int hr = 0;
//graph builder
ICaptureGraphBuilder2 pBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();
hr = pBuilder.SetFiltergraph(pGraph);
checkHR(hr, "Can't SetFiltergraph");
Guid CLSID_VideoCaptureSources = new Guid("{860BB310-5D01-11D0-BD3B-00A0C911CE86}"); //
Guid CLSID_SampleGrabber = new Guid("{C1F400A0-3F08-11D3-9F0B-006008039E37}"); //qedit.dll
//add Camera-M
IBaseFilter pCameraM = CreateFilterByName(@"Camera-M", CLSID_VideoCaptureSources);
hr = pGraph.AddFilter(pCameraM, "Camera-M");
checkHR(hr, "Can't add Camera-M to graph");
//add SampleGrabber
IBaseFilter pSampleGrabber = (IBaseFilter)Activator.CreateInstance(Type.GetTypeFromCLSID(CLSID_SampleGrabber));
hr = pGraph.AddFilter(pSampleGrabber, "SampleGrabber");
checkHR(hr, "Can't add SampleGrabber to graph");
AMMediaType pSampleGrabber_pmt = new AMMediaType();
pSampleGrabber_pmt.majorType = MediaType.Video;
pSampleGrabber_pmt.subType = MediaSubType.I420;
pSampleGrabber_pmt.formatType = FormatType.VideoInfo;
pSampleGrabber_pmt.fixedSizeSamples = true;
pSampleGrabber_pmt.formatSize = 88;
pSampleGrabber_pmt.sampleSize = 460800;
pSampleGrabber_pmt.temporalCompression = false;
VideoInfoHeader pSampleGrabber_format = new VideoInfoHeader();
pSampleGrabber_format.SrcRect = new DsRect();
pSampleGrabber_format.TargetRect = new DsRect();
pSampleGrabber_format.BitRate = 110592000;
pSampleGrabber_format.AvgTimePerFrame = 333333;
pSampleGrabber_format.BmiHeader = new BitmapInfoHeader();
pSampleGrabber_format.BmiHeader.Size = 40;
pSampleGrabber_format.BmiHeader.Width = 640;
pSampleGrabber_format.BmiHeader.Height = 480;
pSampleGrabber_format.BmiHeader.Planes = 1;
pSampleGrabber_format.BmiHeader.BitCount = 12;
pSampleGrabber_format.BmiHeader.Compression = 808596553;
pSampleGrabber_format.BmiHeader.ImageSize = 460800;
pSampleGrabber_pmt.formatPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(pSampleGrabber_format));
Marshal.StructureToPtr(pSampleGrabber_format, pSampleGrabber_pmt.formatPtr, false);
hr = ((ISampleGrabber)pSampleGrabber).SetMediaType(pSampleGrabber_pmt);
DsUtils.FreeAMMediaType(pSampleGrabber_pmt);
checkHR(hr, "Can't set media type to sample grabber");
//connect Camera-M and SampleGrabber
hr = pGraph.ConnectDirect(GetPin(pCameraM, "Capturer"), GetPin(pSampleGrabber, "Input"), null);
checkHR(hr, "Can't connect Camera-M and SampleGrabber");
}
public static IBaseFilter CreateFilterByName(string filterName, Guid category)
{
int hr = 0;
DsDevice[] devices = DsDevice.GetDevicesOfCat(category);
foreach (DsDevice dev in devices)
if (dev.Name == filterName)
{
IBaseFilter filter = null;
IBindCtx bindCtx = null;
try
{
hr = CreateBindCtx(0, out bindCtx);
DsError.ThrowExceptionForHR(hr);
Guid guid = typeof(IBaseFilter).GUID;
object obj;
dev.Mon.BindToObject(bindCtx, null, ref guid, out obj);
filter = (IBaseFilter)obj;
}
finally
{
if (bindCtx != null) Marshal.ReleaseComObject(bindCtx);
}
return filter;
}
return null;
}
[DllImport("ole32.dll")]
public static extern int CreateBindCtx(int reserved, out IBindCtx ppbc);
static IPin GetPin(IBaseFilter filter, string pinname)
{
IEnumPins epins;
int hr = filter.EnumPins(out epins);
checkHR(hr, "Can't enumerate pins");
IntPtr fetched = Marshal.AllocCoTaskMem(4);
IPin[] pins = new IPin[1];
while (epins.Next(1, pins, fetched) == 0)
{
PinInfo pinfo;
pins[0].QueryPinInfo(out pinfo);
bool found = (pinfo.name == pinname);
DsUtils.FreePinInfo(pinfo);
if (found)
return pins[0];
}
checkHR(-1, "Pin not found");
return null;
}
static void checkHR(int hr, string msg)
{
if (hr < 0)
{
Console.WriteLine(msg);
DsError.ThrowExceptionForHR(hr);
}
}
}
}
Can you help me find the reason for this bug?
Thank you for your help.
Regards
Alain
