Methods and apparatus are provided for interfacing a plurality of encoded serial data streams, such as Serial Gigabit Media Independent Interface streams, to a serializer/deserializer circuit. A plurality of encoded serial data streams are transmitted by receiving the plurality of encoded serial data streams that have been encoded using an encoding scheme that provides a substantially uniform distribution of a first code and a second code; marking at least one of the encoded serial data streams (such as changing a first code to a predefined code); and combining at least two of the plurality of encoded serial data streams into a single data stream. A plurality of encoded serial data streams are received by receiving a single data stream comprised of the plurality of encoded serial data streams; detecting a mark in the single data stream; demultiplexing the single data stream into the plurality of encoded serial data streams based on the mark; and providing the demultiplexed plurality of encoded serial data streams to a decoder that decodes the plurality of encoded serial data streams using a decoding scheme that provides a substantially uniform distribution of a first code and a second code.