Applicability of Virtual DirectShow Sources

Virtual DirectShow  sources have been a long time synonym of software-only camera implementation exposed to applications along with physical cameras in a way that applications consume the sources without making a difference whether the camera is real or virtual. Vivek’s template was a starting point for many:

Capture Source Filter filter (version 0.1) 86 KB zipped, includes binaries.  A sample source filter that emulates a video capture device contributed by Vivek (rep movsd from the public newsgroups).  Thanks Vivek!  TMH has not tested this filter yet.  Ask questions about this on microsoft.public.win32.programmer.directx.video.

With API changes over years, the sample and the concept is still understood as the method of adding a virtual camera, however new scenarios exist where the concept no longer works. Typical problems:

  1. 64-bit applications cannot consume virtual 32-bit virtual sources
  2. Virtual sources are no visible and accessible to applications consuming video using Media Foundation API

The diagram below explains the applicability of virtual cameras:

Applicability of Virtual DirectShow Sources

Important is that virtual sources can only be consumed by the DirectShow-based applications of the same bitness.

If source developer needs to synchronize virtual source throughout multiple applications (e.g. video is synthesized by another application and needs to be deliverable to multiple clients), he needs to add interprocess synchronization on the backyard of virtual source.

If developer needs to support both 32- and 64-bit apps, he needs both variants of virtual sources registered, and possibly synchronization of the kind of the paragraph above.

The only virtual device which is visible to all video capture applications if implemented by kernel level driver (implementations are rare but exist).

See also:

Intel® RealSense™ Camera in DirectShow/Media Foundation

There is an intersting submission for video capture device capabilities for “The Short-Range Intel® RealSense™ Camera F200” camera. Another blog user earlier mentioned they have a good stock of the devices with plans to take advantage of new technology.

Intel Realsense camera ad from Intel website

It sounds like the new cameras offer new opportunities for application in user interaction, in ability to conveniently enhance user experience with things like gestures etc.

This is what the camera looks like on the software side:

  • Intel(R) RealSense(TM) 3D Camera Virtual Driver
  • Intel(R) RealSense(TM) 3D Camera (Front F200) RGB
  • Intel(R) RealSense(TM) 3D Camera (Front F200) Depth

Presumably, there are synchronized video and depth sources. It might so happen that SDK offers other presentations of the data (snapshots for combined data and combined stream?).

So what it is all about in terms of how it looks for a video capture application and APIs? The video sensor offers standard video caps and YUV 4:2:2 video stream at 60 fps at resolutions up to 960×540, higher resolutions up to 1920×1080 at 30 fps. This exceeds USB 2.0 bandwidth, so this is either USB 3.0 device or there is hardware compression, with internal software decompression. The video device does not offers compressed video feed capabilities.

There is another video source named “Depth”. It offers YUY2 feed as well as other options with fancy FourCCs (ILER, IRNI, IVNI, IZNI, RVNI, ZVNI?) which is presumably delivering depth information at 640×480@60. Respective SDK is supposedly have the formats documented.

At 60 frames per second and supposedly low latency, the data should be a source of good real-time information to track gestures and reconstruction of short range 3D scene in front of the camera.

Original DirectShow and Media Foundation capability files:

Additional in-depth information about the technology:

IP Video Source: Support for HTTPS protocol

This publishes a small update to IP Video Source tool to expose M-JPEG/JPEG video streams as DriectShow video devices. The utility now accepts https:// URL scheme and pulls video over secure connections. Not every camera has support for HTTPS, however many do including those from UDP Technology, Axis etc.

The update also includes other minor fixes including more reasonable memory allocation, and hotfix for D-Link DCS-930L model, which – to mention – is an excellent indication of quality of camera firmware nowadays (it has nothing to do with D-Link, most of vendors do things like this):

#pragma region D-Link DCS-930L Fix
// NOTE: This is just ridiculous, the camera sends boundary with space without quotes AND misuses -- prefix
if(sValue.Compare(L"multipart/x-mixed-replace;boundary=--video boundary--") == 0)
    sValue = L"multipart/x-mixed-replace;boundary=\"video boundary--\"";
#pragma endregion

Download links

Using IP Video Source programmatically as a standalone DirectShow Video Source Filter for JPEG and M-JPEG IP Cameras

Recent IP Video Source class/module is not limited to use via registration as a video input/capture/source device. The filter is also registered as a regular filter and can be used programmatically in a regular way: CoCreateInstance, AddFilter etc.

A C++ code snippet below shows how to import interface definition, create an instance of the filter, set it up and start video from a camera:

#include <dshow.h>
#pragma comment(lib, "strmiids.lib")

#import "libid:BDCE8B49-8895-4605-8278-E9A1FBC889AC" no_namespace raw_interfaces_only raw_dispinterfaces named_guids // IpVideoSource

// [...]

inline VOID ATLENSURE_INLINE_SUCCEEDED(HRESULT nResult)
{
    ATLENSURE_SUCCEEDED(nResult);
}

// [...]

CComPtr<IBaseFilter> pBaseFilter;
ATLENSURE_INLINE_SUCCEEDED(pBaseFilter.CoCreateInstance(CLSID_JpegVideoSourceFilter));
CComQIPtr<IJpegVideoSourceFilter> pJpegVideoSourceFilter = pBaseFilter;
ATLENSURE_THROW(pJpegVideoSourceFilter, E_NOINTERFACE);
ATLENSURE_INLINE_SUCCEEDED(pFilterGraph->AddFilter(pBaseFilter, L"Source"));

ATLENSURE_INLINE_SUCCEEDED(pJpegVideoSourceFilter->put_Location(CComBSTR(_T("http://p.viewnetcam.com:60001/nphMotionJpeg?Resolution=640x480&Quality=Standard"))));
ATLENSURE_INLINE_SUCCEEDED(pJpegVideoSourceFilter->put_Width(640));
ATLENSURE_INLINE_SUCCEEDED(pJpegVideoSourceFilter->put_Height(480));

#pragma region Render Output Pin
CComPtr<IEnumPins> pEnumPins;
ATLENSURE_INLINE_SUCCEEDED(pBaseFilter->EnumPins(&pEnumPins));
CComPtr<IPin> pPin;
ATLENSURE_THROW(pEnumPins->Next(1, &pPin, NULL) == S_OK, E_FAIL);
ATLASSERT(pPin);
ATLENSURE_INLINE_SUCCEEDED(pFilterGraph->Render(pPin));
#pragma endregion

This starts M-JPEG video from Panasonic BB-HCM381A camera available to public online at http://p.viewnetcam.com:60001/nphMotionJpeg?Resolution=640×480&Quality=Standard

UPDATE: ATLENSURE_SUCCEEDED macro in the snippet replaced with ATLENSURE_INLINE_SUCCEEDED – see additional post on this.

C#.NET code snippet will look like this (using DirectShowLib):

using DirectShowLib;
using AlaxInfoIpVideoSource;

// [...]

FilterGraph filterGraph = new FilterGraph();
IJpegVideoSourceFilter sourceFilter = Activator.CreateInstance(Type.GetTypeFromCLSID(new Guid("{A8DA2ECB-DEF6-414D-8CE2-E651640DBA4F}"))) as IJpegVideoSourceFilter;
IBaseFilter sourceBaseFilter = sourceFilter as IBaseFilter;
(filterGraph as IFilterGraph2).AddFilter(sourceBaseFilter, "Source");
sourceFilter.Location = @"http://p.viewnetcam.com:60001/nphMotionJpeg?Resolution=640x480&Quality=Standard";
sourceFilter.Width = 640;
sourceFilter.Height = 480;
IPin pin = DsFindPin.ByDirection(sourceBaseFilter, PinDirection.Output, 0);
(filterGraph as IFilterGraph2).Render(pin);
(filterGraph as IMediaControl).Run();
EventCode eventCode;
(filterGraph as IMediaEvent).WaitForCompletion(-1, out eventCode);

IP Video Source: Pure JPEG URLs and Software Version

This does not update the software with new features, but there are a few simple things worth mentioning explicitly.

The first is that virtual DirectShow camera device can be set up with both M-JPEG and JPEG URLs. That is, IP cameras which do not implement M-JPEG, or implement it in a buggy way (there is a *huge* deal of such out there) can still be set up to send video as individual video frames/images as long as they implement JPEG snapshots. This is taking place often at a lower frame rate, but still works.

The driver will automatically detect type of URL (by response from the device) and will choose best access method for the given URL.

Second is that if you are looking for IP Video Source software version, such as to check against available updates, it is here on the UI (right click the caption):

IP Video Source: 64-bit version, resolution flexibility, Adobe FMLE

The IP Video Source update provides several improvements to the driver:

  • copy/paste feature to backup, restore, or synchronize installed devices between 32-bit and 64-bit versions
  • 64-bit version and .MSI
  • dynamic video resizing (via Video Resizer DSP)
  • Adobe FMLE compatibility

Updates in greater detail follow.

Device Copy/Paste Feature

The video device management window is providing Copy and Paste buttons, which let user transfer device information, including name and settings, through clipboard for various purposes:

  • save data in order to be able to restore devices later
  • restore devices from saved list, or re-create from a list saved on another machine
  • duplicate a device
  • synchronize devices between 32-bit and 64-bit versions

The device data is a text, one line per device, lines in comma-separated values (CSV) format.

Continue reading →

DirectShow Video Source Filter for JPEG and M-JPEG IP Cameras

This implements a DirectShow driver/wrapper over a HTTP based JPEG/M-JPEG streamed video, widely available with IP cameras. Once installed, it provides a Start Menu shortcut to manage video capture devices, where a user can add/remove devices. The devices are automatically registered with DriectShow and are available to applications.

The compatibility list includes:

  • Windows SDK AmCap Sample (reference)
  • VideoLan VLC
  • Skype (see below)
  • Google Talk Video Chat
  • Luxriot (as rather an example as Luxriot has its own generic JPEG/M-JPEG device driver, however this still demonstrates compatibility and interoperability of applications)
  • GraphEdit, GraphStudio and similar tools

Continue reading →