[FFmpeg-devel] Possible new feature: moving zoom

[Mark Roberts]

Dear list!

I am planning to implement a feature I need in ffmpeg.c. We have several 
recordings of theatre performances in high resolution video made with a 
camcorder on a fixed stand. I would like to add a virtual hand-held 
effect, that is: zoom in on the active character, follow him about the 
stage, zoom out again, that sort of thing.

I would create a configuration file which states, for every frame of the 
film, the rectangle I want zooming to full size. The better the config, 
the better the result. For instance, if the rectangle corners follow 
spline curves, the zooming will look smooth. As if filmed by a good camera 
man.

Is anybody but me interested in this feature? It would consist of a 
command-line option like "-zoomconfig <filename>" and some additional 
clipping and rescaling in ffmpeg.c:do_video_out().

If anybody wants it, I will have to watch the identation :) otherwise I'll 
just hack it and keep it to myself.


Two more cool feature could be (1) incorporating the computation of the 
spline curves in ffmpeg (thus the config file need not state anything like 
so many rectangles), and (2) creating the config file while watching the 
film with ffplay, using the mouse.

Needless to say: all this is only possible because the ffmpeg code base is 
so good. Thank you for providing it!

Any comments?
Thanks,
Mark Roberts