Hello.
I am trying to implement a class, that would give the user the ability to save specified frames of a given video into a file. I already know how to do this and I am using IMFSourceReader for this purpose. However, I am interested only in key frames of the video. So I need the ability to find the nearest key frame to a specified position in video or at least, I need to be able to tell if given sample from a video corresponds to a key frame.
There is a service IMFSeekInfo, which would do the job it seems, but I am not sure how to obtain this service. The documentation says that to obtain this service, one has to call MFGetService with identifier MF_SCRUBBING_SERVICE, but it isn't even mentioned in the list of service interfaces in media foundation documentation and I don't know if it is even defined in some header (my guess is it should be defined in mfidl.h, but it is not).
I would very much appreciate any help with this. Thank you.