Hybrid perceptual audio coding
CA 2037780 C · Owner: American Telephone And Telegraph Company · Inventors: Johnston, James David; Brandenburg, Karlheinz
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A hybrid coding technique for high quality coding of audio signals using a subband filtering technique further refined to achieve a large number ofsubbands. Noise masking thresholds for subbands are then determined using a new tonality measure applicable to individual frequency bands or single frequencies.Based on the thresholds so determined input signals are coded to achieve high quality at reduced bit rates.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 7, 1991 and granted July 2, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 7, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 7, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.