So if Blender is to 3d Studio Max what the GIMP is to Photoshop, what is the Linux equivilent to Combustion?

I work in TV/Video at that borderline area of some broadcast, some industrial, and I'm picturing a system with Cinelerra, (Or something that's a worthy replacement to the Avid) the GIMP, Blender, and----Well, what would be good composting software?