1. A method of controlling distribution of content-related metadata from different content-related sources, said method comprising: a) receiving said metadata at an intermediate location between said content-related sources and a recommender engine, wherein said metadata is metadata of a content item to be played out on a personalized content channel; b) processing the received metadata at said intermediate location to transform a received format of said received metadata into a predetermined common format used by said recommender engine, wherein the recommender engine is associated with the personalized content channel; c) forwarding the processed metadata to a metadata base, wherein the metadata base is connected to the recommender engine via a pre-selection filter for filtering content items; and d) checking whether said received format of said received metadata is a known format, and if said received format is an unknown format, discarding said received metadata, sending information about the unknown format to a source of said received metadata and prompting said source to use a different format for said metadata of said content item.