GitLab

is specified

 * picture.* : add picture-id option. its a string that identifies the
               video.
 * mosaic.c : add mosaic-order option. its a comma separated list of
              picture-ids. Any picture who's id isn't found in the list
              will be placed after skiping the necessary number of
              slots needed to place all pictures defined in this list.

                            parameters on the fly
 * mosaic.c : center image in rectangle when keep aspect ratio is enabled
 * picture.c : remove debug message

 * mosaic.c : add a switch to keep aspect ratio when resizing

 * picture.c picture.h : vout that copies the rendered image in a libvlc
                         object.
 * mosaic.c : sub filter that takes all the images created by the picture
              module and blends them over the current video

I think i still have loads of things to fix (like memleaks)

Simple vlm configuration file to see this work :
<<<<
new chan1 broadcast enabled
setup chan1 input somevideo1.avi
setup chan1 option vout=picture

new chan2 broadcast enabled
setup chan2 input somevideo2.avi
setup chan2 option vout=picture

new bg broadcast enabled
setup bg input somevideo0.avi
setup bg option sub-filter=mosaic

control bg play
control chan1 play
control chan2 play
>>>>

You just have to launch : ./vlc -I telnet --vlm-conf vlm.conf