使用 DirectShow 捕获音频
我正在编写使用 DirectShow 库在 C# 中捕获音频并将其写入 ogg 容器的程序。我在 GraphEditPlus 中创建了一个图表。它生成一个 GraphBuilder 方法代码,我将其复制到我的代码中。这段代码是:
class AudioCapture
{
public static void checkHR(int hr, string msg)
{
if (hr < 0)
{
MessageBox.Show(msg);
DsError.ThrowExceptionForHR(hr);
}
}
public static void BuildGraph (IGraphBuilder pGraph, string dstFile)
{
int hr = 0;
//graph builder
ICaptureGraphBuilder2 pBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();
hr = pBuilder.SetFiltergraph(pGraph);
checkHR(hr, "Can't SetFiltergraph");
Guid CLSID_XiphOrgVorbisEncoder = new Guid("{5C94FE86-B93B-467F-BFC3-BD6C91416F9B}");
Guid CLSID_XiphOrgOggMuxer = new Guid("{1F3EFFE4-0E70-47C7-9C48-05EB99E20011}");
//add microphone
IBaseFilter pMicrophone = (IBaseFilter) new AudioRecord();
hr = pGraph.AddFilter(pMicrophone, "Microphone");
checkHR(hr, "Can't add microphone to graph");
//add Vorbis Encoder
IBaseFilter pVorbisEncoder = (IBaseFilter)Activator.CreateInstance(Type.GetTypeFromCLSID(CLSID_XiphOrgVorbisEncoder));
checkHR(hr, "Can't add Vorbis Encoder to graph");
//connect Microphone and Vorbis Encoder
hr = pGraph.ConnectDirect(GetPin(pMicrophone, "Capture"), GetPin(pVorbisEncoder, "PCM In"), null);
checkHR(hr, "Can't connect Microphone and Vorbis Encoder");
//add Ogg Muxer
IBaseFilter pOggMuxer = (IBaseFilter)Activator.CreateInstance(Type.GetTypeFromCLSID(CLSID_XiphOrgOggMuxer));
checkHR(hr, "Can't add Ogg Muxer to graph");
//set destination filename
IFileSinkFilter pOggMuxer_sink = pOggMuxer as IFileSinkFilter;
if (pOggMuxer_sink == null)
checkHR(unchecked((int)0x80004002), "Can't get IFileSinkFilter");
hr = pOggMuxer_sink.SetFileName(dstFile, null);
checkHR(hr, "Can't set filename");
//connect Vorbis Encoder and Ogg Muxer
hr = pGraph.ConnectDirect(GetPin(pVorbisEncoder, "VorbisOut"), GetPin(pOggMuxer, "Ogg Packet In"), null);
checkHR(hr, "Can't connect Vorbis Encoder and Ogg Muxer");
}
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;
}
}
当我尝试执行此代码时,在尝试连接麦克风和 vorbis 编码器过滤器后,程序向我抛出一条消息“无法找到 Pin”。经过调试发现找不到麦克风引脚。有谁知道我的错误在哪里?
I'm writing program which captures audio in C# using DirectShow library and writes it to ogg container. I created a graph in GraphEditPlus. It generates a GraphBuilder method code which I copied to my code. This code is:
class AudioCapture
{
public static void checkHR(int hr, string msg)
{
if (hr < 0)
{
MessageBox.Show(msg);
DsError.ThrowExceptionForHR(hr);
}
}
public static void BuildGraph (IGraphBuilder pGraph, string dstFile)
{
int hr = 0;
//graph builder
ICaptureGraphBuilder2 pBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();
hr = pBuilder.SetFiltergraph(pGraph);
checkHR(hr, "Can't SetFiltergraph");
Guid CLSID_XiphOrgVorbisEncoder = new Guid("{5C94FE86-B93B-467F-BFC3-BD6C91416F9B}");
Guid CLSID_XiphOrgOggMuxer = new Guid("{1F3EFFE4-0E70-47C7-9C48-05EB99E20011}");
//add microphone
IBaseFilter pMicrophone = (IBaseFilter) new AudioRecord();
hr = pGraph.AddFilter(pMicrophone, "Microphone");
checkHR(hr, "Can't add microphone to graph");
//add Vorbis Encoder
IBaseFilter pVorbisEncoder = (IBaseFilter)Activator.CreateInstance(Type.GetTypeFromCLSID(CLSID_XiphOrgVorbisEncoder));
checkHR(hr, "Can't add Vorbis Encoder to graph");
//connect Microphone and Vorbis Encoder
hr = pGraph.ConnectDirect(GetPin(pMicrophone, "Capture"), GetPin(pVorbisEncoder, "PCM In"), null);
checkHR(hr, "Can't connect Microphone and Vorbis Encoder");
//add Ogg Muxer
IBaseFilter pOggMuxer = (IBaseFilter)Activator.CreateInstance(Type.GetTypeFromCLSID(CLSID_XiphOrgOggMuxer));
checkHR(hr, "Can't add Ogg Muxer to graph");
//set destination filename
IFileSinkFilter pOggMuxer_sink = pOggMuxer as IFileSinkFilter;
if (pOggMuxer_sink == null)
checkHR(unchecked((int)0x80004002), "Can't get IFileSinkFilter");
hr = pOggMuxer_sink.SetFileName(dstFile, null);
checkHR(hr, "Can't set filename");
//connect Vorbis Encoder and Ogg Muxer
hr = pGraph.ConnectDirect(GetPin(pVorbisEncoder, "VorbisOut"), GetPin(pOggMuxer, "Ogg Packet In"), null);
checkHR(hr, "Can't connect Vorbis Encoder and Ogg Muxer");
}
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;
}
}
When I'm trying to execute this code program throws me a message "Pin can't found" after trying to connect microphone and vorbis encoder filters. After debugging I found out that it can't find the microphone pin. Does anybody knows where is my error?
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您不应该通过名称来查找引脚,因为这不太可靠。如果您绝对确定要处理的过滤器/类,也许它仍然或多或少可以接受,但这绝对不是处理通用音频源过滤器的方法(更具体地说:没有人承诺捕获引脚被命名为“Capture”,而不是引脚实现 IKsPropertySet 来指示)。
您最好的方法是将
ICaptureGraphBuilder::RenderStream
与PIN_CATEGORY_CAPTURE
参数一起使用,以便它可以为您拾取捕获引脚。有关详细信息,请参阅 MSDN http://msdn.microsoft .com/en-us/library/dd311932%28v=vs.85%29.aspx 我很确定您也可以轻松找到执行此操作的示例代码。You should not look for pins by their names, as this is not quite reliable. Perhaps it might be still more or less acceptable if you are absolutely sure what filter/class you are dealing with, but it is definitely not the way to do with generic audio source filter (more specifically: noone gives a promise that capture pin is named "Capture", instead pins implement
IKsPropertySet
to indicate that).Your best approach would be using
ICaptureGraphBuilder::RenderStream
withPIN_CATEGORY_CAPTURE
argument so that it could pick up capture pin for you. See MSDN for details http://msdn.microsoft.com/en-us/library/dd311932%28v=vs.85%29.aspx and I am pretty sure you will easily find sample code for doing this too.当您寻找引脚时,请尝试执行类似的操作,
这是比根据名称更好的方法。
Try do something like this when you looking for pins
This is better way then depending on names.