The movie preview is a short movie inside a movie file, that is meant to give an idea of what the main movie looks like. In order not to be confused with all those terms, keep in mind that a QuickTime movie is not just the "useful" part that we usually visualize or manipulate; it is a big container that holds a variety of information.
The movie preview is the "thumbnail" of a movie; obviously, the preview is itself a movie too. This is a situation similar to those image files containing a thumbnail of the main image inside them for previeweing purposes.
The movie poster is a movie frame that can be used as a still representation of the movie. Using the poster is useful in media databases, when a movie need be represented without playing it, just like posters are used for advertising real movies outside of theaters or in printed catalogs. Movies may have a poster or not. The poster frame is fully defined by its position in time.
A movie is a sequence of still images, also known as "movie frames". The movie poster is a special movie frame in the sense that only one frame in a movie can be the poster. However, all movie frames, including the poster, are pictures and they can be captured as pictures.
Pictures captured from movies in this way can further be processed, compressed, etc using QPix. The same goes for the poster picture.
Getting the picture of a VR movie
Exceptionally, you should use the QM_GetPosterPict command to get the current picture of a VR movie. Using QM_GetMoviePict will not yield what you expect because this command needs to refer to time and the notion of time is not straightforward in VR movies.
|QM_GetPreviewTime||Returns the movie's preview time.|
|QM_GetPosterTime||Returns the movie's poster time.|
|QM_GetPosterPict||Returns the movie's poster pict.|
|QM_GetMoviePict||Creates and returns a picture from a movie.|