A portion of the number of bits initially allocated for encoding some of the frames of a group of pictures is accumulated in a bit bank and is subsequently used to encode other frames that may require a larger number of bits to encode than those initially allocated for these frames. Specifically, the method of the present invention includes an anodization step which is capable of converting a portion of base resistor film into an anodized region. The magnets are in attractive magnetic communication when the temple bars are closed. A compression procedure can be neglected, thereby saving more manufacturing cost and offering a higher structural strength for the sealing part. The method includes the steps of unwinding an end portion of each foil 410 over a given length, turning each end portion back on itself to constitute the free strand 413 of an open loop 414, unwinding each free strand 413 along the feed path by pulling the corresponding foil 410 from the inside of its loop 414, while partially restraining each free strand 413 as it deploys along the feed path. The power converter includes a first controller 18 for the first active rectifierinverter and a second controller 20 for the second active rectifierinverter.