DirectShow Custom Source Pin - wpf

Question

I am new to DirectShow. I, like many others, am trying to create a socket-based P2P streaming solution for a WPF-based card game. I want each player to be able to see each other via small video windows.
My questions are two-fold. The first is How do I lower the frame sample rate and resolution? I believe 320x200 x 15 to 20 fps should be fine. I am using the SampleGrabber callback to grab frame data and send it over the socket; which is actually working with no compression at 640x480 resolution.
My second question is, since each frame contains 921,600 bytes, this really bogs down and I get very slow rendering just across my local WiFi connected LAN. I added a simple MJPEG compression (wanting to switch to h.264 later) and I noticed the bytes drop to around 330-360k. Not a bad improvement.
On the receiving end Do I need to create a custom DirectShow Source Pin in order to serve up the bytes received from the socket so I can attach a decoder and render the bytes in a window?
I just wanted to ask this first since it seems like a lot of work to create a new COM object (haven't done that in about 15 years!), register it, and use/debug it.
Is there perhaps another way?
Also if that is the way to go, should I use a SampleGrabber on the receiving end and create a BitmapSource from the decompressed bytes, or should I allow DirectShow to create a child window? Thing is, I want to have more than one other player and I set an extra byte in the socket to tell what table position they are in. How do I render each position in turn?

Answer 1

For those that are interested, here is how you set the resolution and add an encoder/compressor:
// Create a graph builder
int hr = captureGraphBuilder.SetFiltergraph(graphBuilder);
// Find a capture device (WebCam) and attach it to the graph
sourceFilter = FindCaptureDevice();
hr = graphBuilder.AddFilter(sourceFilter, "Video Capture");
// Get the source output Pin
IPin sourcePin = DsFindPin.ByDirection((IBaseFilter)sourceFilter, PinDirection.Output, 0);
IAMStreamConfig sc = (IAMStreamConfig)sourcePin;
int count;
int size;
sc.GetNumberOfCapabilities(out count, out size);
VideoInfoHeader v;
AMMediaType media2 = null;
IntPtr memPtr = Marshal.AllocCoTaskMem(size);
for (int i = 0; i < count; ++i)
{
sc.GetStreamCaps(i, out media2, memPtr);
v = (VideoInfoHeader)Marshal.PtrToStructure(media2.formatPtr, typeof(VideoInfoHeader));
// Break when width is 160
if (v.BmiHeader.Width == 160)
break;
}
// Set the new media format t0 160 x 120
hr = sc.SetFormat(media2);
Marshal.FreeCoTaskMem(memPtr);
DsUtils.FreeAMMediaType(media2);
// Create a FramGrabber
IBaseFilter grabberF = (IBaseFilter)new SampleGrabber();
ISampleGrabber grabber = (ISampleGrabber)grabberF;
// Set the media type
var media = new AMMediaType
{
majorType = MediaType.Video,
subType = MediaSubType.MJPG
//subType = MediaSubType.RGB24
};
// The media sub type will be MJPG
hr = grabber.SetMediaType(media);
DsUtils.FreeAMMediaType(media);
hr = grabber.SetCallback(this, 1);
hr = graphBuilder.AddFilter(grabberF, "Sample Grabber");
IPin grabberPin = DsFindPin.ByDirection(grabberF, PinDirection.Input, 0);
// Get the MPEG compressor
Guid iid = typeof(IBaseFilter).GUID;
object compressor = null;
foreach (DsDevice device in DsDevice.GetDevicesOfCat(FilterCategory.VideoCompressorCategory))//.MediaEncoderCategory))
{
if (device.Name == "MJPEG Compressor")
{
device.Mon.BindToObject(null, null, ref iid, out compressor);
hr = graphBuilder.AddFilter((IBaseFilter)compressor, "Compressor");
break;
}
string name = device.Name;
}
// This also works!
//IBaseFilter enc = (IBaseFilter)new MJPGEnc();
//graphBuilder.AddFilter(enc, "MJPEG Encoder");
// Get the input and out pins of the compressor
IBaseFilter enc = (IBaseFilter)compressor;
IPin encPinIn = DsFindPin.ByDirection(enc, PinDirection.Input, 0);
IPin encPinOut = DsFindPin.ByDirection(enc, PinDirection.Output, 0);
// Attach the pins: source to input, output to grabber
hr = graphBuilder.Connect(sourcePin, encPinIn);
hr = graphBuilder.Connect(encPinOut, grabberPin);
// Free the pin resources
Marshal.ReleaseComObject(sourcePin);
Marshal.ReleaseComObject(enc);
Marshal.ReleaseComObject(encPinIn);
Marshal.ReleaseComObject(encPinOut);
Marshal.ReleaseComObject(grabberPin);
// Create a render stream
hr = captureGraphBuilder.RenderStream(PinCategory.Preview, MediaType.Video, sourceFilter, null, grabberF);
Marshal.ReleaseComObject(sourceFilter);
Configure(grabber);