These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.02 s (backtrack: 0/20).

[ebuild  N     ] sys-libs/libraw1394-2.1.2-r1::gentoo  USE="-valgrind" 306 KiB
[ebuild  N     ] dev-libs/libusb-1.0.30:1::gentoo  USE="-debug -doc -examples -static-libs -test -udev -verify-sig" 641 KiB
[ebuild  N     ] virtual/libusb-1-r2:1::gentoo  USE="-udev" 0 KiB
[ebuild  N     ] media-libs/libdc1394-2.2.6:2/25::gentoo  USE="-doc -static-libs" 601 KiB

Total: 4 packages (4 new), Size of downloads: 1547 KiB