[Libav-user] AVFilter overlay change image

Stefano Sabatini stefasab at gmail.com
Fri Feb 10 00:14:56 CET 2012

On date Thursday 2012-02-09 16:53:12 +1300, Kenneth Gibson encoded:
> Hi,
> I am using Libavfilter programmatically and I know its possible to overlay
> an image like a logo onto a video with a filterchain.
> Is it possible to change the image that I am overlaying part way through
> the video?

You can push events into the filtergraph and make every filter process
them. Right now this interface is implemented only in drawtext, but
adding that capability to the overlay filter should be
straightforward, and patches are welcome in this case.

> The idea being that the overlaid image will change every *n* number of
> frames.
> Is this possible with a filtergraph?

You may programmatically push a reconfiguration event every n frames.

> The only other way I can think of is to make a separate video where each
> frame contains my overlay image with a transparent background. Then overlay
> one on top of the other. Does this sound viable?

More information about the Libav-user mailing list