Dolby Pro Logic II (DPL II) has become the second matrixed-surround format to be approved by HD Radio inventor iBiquity for use by digital AM and FM broadcasters. Circle Surround II (CS II) was approved more than a year ago.
During the National Association of Broadcasters (NAB) convention, here, broadcast-equipment supplier Broadcast Electronics demonstrated a DPL II encoder that broadcast stations would use to transmit stereo-compatible 5.1-channel music from multichannel recordings, including multichannel music played from DVD-Audio discs and Super Audio CDs. Home and car audio systems equipped with Pro Logic II decoders would hear the music the way it was mixed. Home and car systems using other surround decoders, including CS II decoders, would also deliver a surround-sound experience, but not necessarily in the way that the music was originally mixed, the companies said.
Likewise, CS II decoders would play back CSII-encoded programs in the way the music was originally mixed, the company said. CS II encoders were available for sale to radio stations by early 2004.
Three other surround-sound technologies are also competing for adoption by radio stations that plan to convert to digital. They will deliver five discrete channels rather than five matrixed channels, but they are nonetheless said to be backward-compatible with two-channel HD Radio receivers. Two of the technologies are from radio-station suppliers Telos and Neural, which have also demonstrated its technology with XM Satellite Radio. The third technology, called HDC Surround, was developed jointly by Coding Technologies, a developer of audio compression technologies.