Abstract

Broadcasters are now transmitting 5.1-channel surround sound as part of their HD TV services. However, since much of the audio content in original programme material is 2-channel stereo, broadcasters are required to switch between the two formats. Switching between 2- and 5.1-channel formats can cause problems in decoding the content, including switching artefacts, video synchronisation and loudness changes. In general it is preferable to transmit all programme audio in 5.1 surround, and this can be achieved by automatically upmixing any 2-channel stereo content to 5.1 format prior to broadcasting. This paper reports on tests designed to assess the subjective performance of a selection of upmixers for use in the broadcast chain.