A media converter, a system and a method for converting packet based data into serial data and vice versa are provided. The media converter comprises a first interface configured to receive and provide a first type of data stream based on data packets, a second interface configured to receive and provide a second type of data stream based on a continuous serial bit stream, and a signal processor connected to the first and second interfaces and configured to convert said first type of data stream into said second type of data stream and vice versa on the basis of a block encoding/decoding algorithm and a line encoding/decoding algorithm. Thus, enhanced bit error rate may be obtained, thereby allowing the use of optical transmission channels of increased length.