qedit: Implement partially the Sample Grabber filter

[Rob Shearman]

2009/12/23 Paul Chitescu <paulc at voip.null.ro>:
> Changelog:
>        qedit: Implement partially the Sample Grabber filter
>
> The IMediaPosition, IMediaSeeking and IQualityControl interfaces are currently
> not implemented at all. No programs I've tested tried to query them though.
>
> Buffering of samples is also not implemented yet, applications usually install
> an ISampleGrabberCB callback.

Thread-safety is non-existent in your newly written code. DirectShow
uses multiple threads so I would say thread-safety is a requirement,
not a nice-to-have.

-- 
Rob Shearman