using QTNewGWorldFromPtr to switch offscreen buffer

Hi all,

 

I wrote some code that basically changes the offscreen buffer on a frame by frame basis in between MoviesTask calls, my goal is to have quicktime draw into my own buffers which I can then use for purposes other than rendering to the screen. The code I have now is relatively slow I’d like to have your inputs on how I can make it more efficient.

 

I found that every time I wanted quicktime to draw into a different buffer I had to dispose of the old GWorld and re-create a new one. The sequence I use is the following:

 

DisposeGWorld

QTNewGWorldFromPtr

SetMovieGWorld

 

I timed this sequence and it’s consuming 500 micro seconds in NTSC which is relatively very significant since all I want to do after all is reset a pointer somewhere in quicktime, I’m not allocating any resources or doing anything fancy.

 

Can anyone please provide some pointers as to what I could do to speed things up, maybe use a different subset of the quicktime API?

 

Thanks!

 

Christian Bechette

www.matrox.com/video