[FFmpeg-devel] Possible new feature: moving zoom

Stefano Sabatini stefano.sabatini-lala
Sat Jul 11 22:48:10 CEST 2009

On date Saturday 2009-07-11 19:42:03 +0200, Mark Roberts encoded:
> 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().

ffmpeg.c is not the right place for that, have a look at
libavfilter. Note that a good amount of work is needed to get
libavfilter merged into the main trunk, help in that area is very

> 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!

FFmpeg = Furious & Faboulous Multipurpose Puristic Experimenting Game

More information about the ffmpeg-devel mailing list