How to use transitions between frames

For smooth switching between sources, you can use transitions between frames. 

You can do it with the MFTransition method. This method mixes 2 source frames according to given parameters and returns you a mixed frame. You can control the position of a transition and its type. 

The method has the parameters:

• _pFrameFrom - a frame from which the transition is used.
• _ppFrameRes - result mixed frame.
• _dblPos - position of a transition.
• _bsTransition - transition type.
• _bsPropsList - additional properties. This property is reserved for future usage.
• _bsConverterID - converter ID. This property is reserved for future usage.

To make a transition you need 2 MFFrame objects. You can receive them from sources or create new ones. 

In common case transition between frames looks like:

// get a frame from 1st source 
MFFrame frameFrom;
myFirstSource.SourceFrameGet(-1, out frameFrom, "");
// get a frame from 2nd source
MFFrame frameTo;
mySecondSource.SourceFrameGet(-1, out frameTo, "");
string transitionType="wheel";
double transitionPos = 0.5;
MFFrame frameResult;
frameTo.MFTransition(frameFrom, out frameResult, transitionPos, transitionType, "", "");

You can use a frameResult object for preview or to output, or whatever you like :) 

The effect depends on a transition position (transitionPos):

• if it is 0.0 the frameResult is equal to frameFrom,
• if it is 1.0 - the frameResult is equal to frameTo

So you can vary a speed of transition by changing transition position parameter. To make transition slower you should set step for transitionPos smaller (for example, 0.01 - in this case a complete transition from 1st source to 2nd one takes 100 frames), and to make it faster you should increase the step (e.g. 0.1 - in this case transition takes only 10 frames).

You can use any transition type that is supported in MFormats SDK. A full list of available transitions types is here.