c++ - Best DirectShow way to capture image from web cam preview ? SampleGrabber is deprecated

Question

I have developed DirectShow C++ app which successfully previews web cam view into provided window. Now I want to capture image from this live web cam preview. I have used graph manager, ICaptureGraphBuilder2, IMoniker etc. for that. I have searched and found following options: WIA & Sample Grabber. Many recommends using SampleGrabber but as per MS's msdn document SampleGrabber is deprecated and one should not use. And I don't want to use WIA API.

So which is the best DirectShow way to capture image from live web cam preview?

Answer 1

Here is a quote from DxSnap sample from DirectShow.NET library:

Use DirectShow to take snapshots from the Still pin of a capture device. Note the MS encourages you to use WIA for this, but if you want to do in with DirectShow and C#, here's how.

Note that this sample will only work with devices that output uncompressed video as RBG24. This will include most webcams, but probably zero tv tuners.

This is C# code, but you should get the idea as the interfaces are all the same. And there are other samples on how to use Sample Grabber Filter in C++.

Sample Grabber is deprecated, the headers are removed from a couple of latest SDKs, however the runtime components are all there and are going to be there for a long time, or otherwise a multitude of application would be broken (e.g. Video Chat in browser hosted GMail is using Sample Grabber). So basically Sample Grabber is still an easy way to capture snapshots from a web camera, or if you alternatively prefer to follow the latest MS APIs - you would want to look into Media Foundation (09 Jul 2016 update: new Windows Server installations might need one to add "Media Foundation" and/or "Desktop Experience" features to make Media Foundation API available along with DirectShow, and DirectShow Editing Services, Sample Grabber is a part of which. Default installation does not offer qedit.dll out of the box).

Also in C++ you certainly don't have to use Sample Grabber Filter. You can develop a custom filter using DirectShow BaseClasses to be a custom transformation filter or a custom renderer, which which accept incoming video feed and export the frames from the DirectShow pipeline. Another option is to use Sample Grabber sample source code from one of the older SDKs (which is not exact source for OS Sample Grabber, but it is doing the same thing). The point however that Sample Grabber shipped with Windows is still a good option.