Error when record audio from webcam

[Thuan Tran]

I am new with DirectShow.Net. I am implementing an C# application to record
video and audio from a webcam to a file (the webcam has a micro). Recording
video is fine but when I add a filter to record audio then it occurs exception
"One or more arguments are invalid". I do not know how to put valid arguments
since I put arguments similarly to rednering the video. Following is my code
and exception occurs at the second last line. Does anyone know how to put
correct arguments?

//Create the Graph
graphBuilder = (IGraphBuilder)new FilterGraph();

//Create the Capture Graph Builder
ICaptureGraphBuilder2 captureGraphBuilder = null;
captureGraphBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();

//Create the media control for controlling the graph
mediaControlList = (IMediaControl)this.graphBuilder;

// Attach the filter graph to the capture graph
int hr = captureGraphBuilder.SetFiltergraph(this.graphBuilder);
DsError.ThrowExceptionForHR(hr);

//Add the Video input device to the graph
IBaseFilter sourceFilter = (IBaseFilter)devices;
hr = graphBuilder.AddFilter(sourceFilter, "The webcam " + (indexOfCamera +
1).ToString());
DsError.ThrowExceptionForHR(hr);

//Add the Video compressor filter to the graph
IBaseFilter videoCompressor = getVideoCompressor();
if (videoCompressor != null)
{
hr = graphBuilder.AddFilter(videoCompressor, "video compressor filter");
DsError.ThrowExceptionForHR(hr);
}

//Add the Video compressor filter to the graph
IBaseFilter audioCompressor = getAudioCompressor();
if (audioCompressor != null)
{
hr = graphBuilder.AddFilter(audioCompressor, "audio compressor filter");
DsError.ThrowExceptionForHR(hr);
}

//Create the file writer part of the graph. SetOutputFileName does this for
us, and returns the mux and sink
IBaseFilter mux = null;
IFileSinkFilter sink = null;
hr = captureGraphBuilder.SetOutputFileName(MediaSubType.Avi, fileName, out
mux, out sink);
DsError.ThrowExceptionForHR(hr);

//Render any preview pin of the device
hr = captureGraphBuilder.RenderStream(PinCategory.Preview, MediaType.Video,
sourceFilter, null, null);
DsError.ThrowExceptionForHR(hr);

//Connect the device and compressor to the mux to render the capture part of
the graph
hr = captureGraphBuilder.RenderStream(PinCategory.Capture, MediaType.Video,
sourceFilter, null, mux);
DsError.ThrowExceptionForHR(hr);

//Render with audio
hr = captureGraphBuilder.RenderStream(PinCategory.Capture, MediaType.Audio,
sourceFilter, null, mux);
DsError.ThrowExceptionForHR(hr);

Thanks,

[snarfle]

Let's take a look at what you are doing to connect the audio:

               //Render with audio
                hr = captureGraphBuilder.RenderStream(PinCategory.Capture,MediaType.Audio, sourceFilter, null, mux);

Now, where do you get the value for sourceFilter?

You don't show where you get "devices", but presumably from using DsDevice? If
so, then the solution here should be obvious.

[Thuan Tran]

Here is how I get the webcams.

// Find all cameras
private void findAllCaptureDevices()
{
System.Collections.ArrayList availableDevices = new
System.Collections.ArrayList();
devices = new System.Collections.ArrayList();

// Get all video input devices
availableDevices.AddRange(DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDe
vice));
foreach (object obj in availableDevices)
{
DsDevice device = (DsDevice)obj;

// Bind Moniker to a filter object
Guid iid = typeof(IBaseFilter).GUID;
object source;
device.Mon.BindToObject(null, null, ref iid, out source);

devices.Add((IBaseFilter)source);
}
}

It seems DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice) does not
include audio. if yes, could you help me to get webcams including both video
and audio since I need to save both video and audio into a file.

[snarfle]

C'mon man. You've got a statement that reads:

DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice)

And you can't figure out what you have to change to get audio devices? You're
kidding, right?

[Thuan Tran]

Your first question help me to figure the problem. I now figured out how to
get video and audio devices separately and successfully recorded audio and
video into a file. But with this solution, the audio devices could not be the
micro of webcams. Is there any way to get both video and audio of webcam into
a device object?

// Find all cameras
private void findAllCaptureDevices()
{
System.Collections.ArrayList availableDevices = new
System.Collections.ArrayList();
videoDevices = new System.Collections.ArrayList();

// Get all video input devices
availableDevices.AddRange(DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDe
vice));
foreach (object obj in availableDevices)
{
DsDevice device = (DsDevice)obj;

// Bind Moniker to a filter object
Guid iid = typeof(IBaseFilter).GUID;
object source;
device.Mon.BindToObject(null, null, ref iid, out source);

videoDevices.Add((IBaseFilter)source);
}

audioDevices = new System.Collections.ArrayList();

// Get usb audio input devices
availableDevices.RemoveRange(0, videoDevices.Count);
availableDevices.AddRange(DsDevice.GetDevicesOfCat(FilterCategory.AudioInputDe
vice));
foreach (object obj in availableDevices)
{
DsDevice device = (DsDevice)obj;
if(device.Name.Contains("USB Audio Device"))
{
// Bind Moniker to a filter object
Guid iid = typeof(IBaseFilter).GUID;
object source;
device.Mon.BindToObject(null, null, ref iid, out source);

audioDevices.Add((IBaseFilter)source);
}
}
}