Method and apparatus for the perceptual coding of audio signals
CA 2090052 C · Owner: American Telephone And Telegraph Company · Inventors: De Sousa Ferreira, Anibal Joao; Johnston, James David
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method and apparatus for performing a Modified Discrete Cosine Transform on an audio signal is disclosed which utilizes a Discrete Fourier Transform. Illustratively, the MDCT spectral coefficients for the signal are generated from the real FFT spectral coefficients.
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 February 22, 1993 and granted November 24, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 22, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 22, 2015.
- 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.