How to access audio stream using DirectShow.NET C #

Question

What I would like to do is transfer an arbitrary sound file to the DirectShow filter and get a stream object (PCM audio) at the end using .NET 3.5 C # and DirectShow.NET. I would like to say that I can say:

Stream OpenFile(string filename) {...} 

and

 stream.Read(...) 

I read on DirectShow a couple of days and I think I started to understand the idea of ​​filters and filters. I found examples ( in a file / on a device ) of how to play sound or write it to a file, but cannot find a solution for the Stream object. Is it possible? Could you point me in the right direction, if I missed something, please?

Best

Hawka

Answer 1

I would like to share my solution with my own problem with you (the focus was on the exotic bwf file, hence the name.):

  using System; using System.Collections.Generic; using System.Text; using DirectShowLib; using System.Runtime.InteropServices; using System.IO; namespace ConvertBWF2WAV { public class BWF2WavConverter : ISampleGrabberCB { IFilterGraph2 gb = null; ICaptureGraphBuilder2 icgb = null; IBaseFilter ibfSrcFile = null; DsROTEntry m_rot = null; IMediaControl m_mediaCtrl = null; ISampleGrabber sg = null; public BWF2WavConverter() { // Initialize int hr; icgb = (ICaptureGraphBuilder2)new CaptureGraphBuilder2(); gb = (IFilterGraph2) new FilterGraph(); sg = (ISampleGrabber)new SampleGrabber(); #if DEBUG m_rot = new DsROTEntry(gb); #endif hr = icgb.SetFiltergraph(gb); DsError.ThrowExceptionForHR(hr); } public void reset() { gb = null; icgb = null; ibfSrcFile = null; m_rot = null; m_mediaCtrl = null; } public void convert(object obj) { string[] pair = obj as string[]; string srcfile = pair[0]; string targetfile = pair[1]; int hr; ibfSrcFile = (IBaseFilter)new AsyncReader(); hr = gb.AddFilter(ibfSrcFile, "Reader"); DsError.ThrowExceptionForHR(hr); IFileSourceFilter ifileSource = (IFileSourceFilter)ibfSrcFile; hr = ifileSource.Load(srcfile, null); DsError.ThrowExceptionForHR(hr); // the guid is the one from ffdshow Type fftype = Type.GetTypeFromCLSID(new Guid("0F40E1E5-4F79-4988-B1A9-CC98794E6B55")); object ffdshow = Activator.CreateInstance(fftype); hr = gb.AddFilter((IBaseFilter)ffdshow, "ffdshow"); DsError.ThrowExceptionForHR(hr); // the guid is the one from the WAV Dest sample in the SDK Type type = Type.GetTypeFromCLSID(new Guid("3C78B8E2-6C4D-11d1-ADE2-0000F8754B99")); object wavedest = Activator.CreateInstance(type); hr = gb.AddFilter((IBaseFilter)wavedest, "WAV Dest"); DsError.ThrowExceptionForHR(hr); // manually tell the graph builder to try to hook up the pin that is left IPin pWaveDestOut = null; hr = icgb.FindPin(wavedest, PinDirection.Output, null, null, true, 0, out pWaveDestOut); DsError.ThrowExceptionForHR(hr); // render step 1 hr = icgb.RenderStream(null, null, ibfSrcFile, (IBaseFilter)ffdshow, (IBaseFilter)wavedest); DsError.ThrowExceptionForHR(hr); // Configure the sample grabber IBaseFilter baseGrabFlt = sg as IBaseFilter; ConfigSampleGrabber(sg); IPin pGrabberIn = DsFindPin.ByDirection(baseGrabFlt, PinDirection.Input, 0); IPin pGrabberOut = DsFindPin.ByDirection(baseGrabFlt, PinDirection.Output, 0); hr = gb.AddFilter((IBaseFilter)sg, "SampleGrabber"); DsError.ThrowExceptionForHR(hr); AMMediaType mediatype = new AMMediaType(); sg.GetConnectedMediaType(mediatype); hr = gb.Connect(pWaveDestOut, pGrabberIn); DsError.ThrowExceptionForHR(hr); // file writer FileWriter file_writer = new FileWriter(); IFileSinkFilter fs = (IFileSinkFilter)file_writer; fs.SetFileName(targetfile, null); hr = gb.AddFilter((DirectShowLib.IBaseFilter)file_writer, "File Writer"); DsError.ThrowExceptionForHR(hr); // render step 2 AMMediaType mediatype2 = new AMMediaType(); pWaveDestOut.ConnectionMediaType(mediatype2); gb.Render(pGrabberOut); // alternatively to the file writer use the NullRenderer() to just discard the rest // assign control m_mediaCtrl = gb as IMediaControl; // run hr = m_mediaCtrl.Run(); DsError.ThrowExceptionForHR(hr); } // // configure the SampleGrabber filter of the graph // void ConfigSampleGrabber(ISampleGrabber sampGrabber) { AMMediaType media; // set the media type. works with "stream" somehow... media = new AMMediaType(); media.majorType = MediaType.Stream; //media.subType = MediaSubType.WAVE; //media.formatType = FormatType.WaveEx; // that the call to the ISampleGrabber interface sg.SetMediaType(media); DsUtils.FreeAMMediaType(media); media = null; // set BufferCB as the desired Callback function sg.SetCallback(this, 1); } public int SampleCB(double a, IMediaSample b) { return 0; } /// <summary> /// Called on each SampleGrabber hit. /// </summary> /// <param name="SampleTime">Starting time of the sample, in seconds.</param> /// <param name="pBuffer">Pointer to a buffer that contains the sample data.</param> /// <param name="BufferLen">Length of the buffer pointed to by pBuffer, in bytes.</param> /// <returns></returns> public int BufferCB(double SampleTime, IntPtr pBuffer, int BufferLen) { byte[] buffer = new byte[BufferLen]; Marshal.Copy(pBuffer, buffer, 0, BufferLen); using (BinaryWriter binWriter = new BinaryWriter(File.Open(@"C:\directshowoutput.pcm", FileMode.Append))) { binWriter.Write(buffer); } return 0; } } } 

Answer 2

This ( AVILibrary Wrapper ) may lead you to a decision, it is not based on DirectSound (which, it seems to me, is very biased regarding pairing your code with reproducing equipment), but may be the answer.

Another approach can be found here .

Answer 3

How about NAudio? http://www.codeplex.com/naudio It has a stream implementation.