HDC (Hybrid Digital Coding or High-Definition Coding) with SBR (spectral band replication) is a proprietary lossy audio compression codec developed by iBiquity for use with HD Radio. It replaced the earlier PAC codec in 2003.[1][2] In June 2017, the format was reverse engineered and determined to be a variant of HE-AACv1.[3] It uses a modified discrete cosine transform (MDCT) audio coding data compression algorithm.[4]


  1. ^ "Radio and WIreless: AM Bandwidth and Digital Radio". Archived from the original on 2008-06-07. Retrieved 2007-10-07.
  2. ^ Optimization of high-definition video coding and hybrid fiber-wireless transmission in the 60 GHz band
  3. ^ "Receiving NRSC-5". Theori. Archived from the original on 20 August 2017. Retrieved 14 April 2018.
  4. ^ Jones, Graham A.; Layer, David H.; Osenkowsky, Thomas G. (2013). National Association of Broadcasters Engineering Handbook: NAB Engineering Handbook. Taylor & Francis. pp. 558–9. ISBN 978-1-136-03410-7.