Audio codec using the Fast Fourier Transform, the partial overlap and a decomposition in two plans based on the energy.
First Claim
1. ) A method of audio compression and decompression comprising the use of the Fast Fourier Transform (FFT) for the voice and the music and a decomposition in two plans based on the energy.
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Abstract
Audio codec using the Fast Fourier Transform, the partial overlap and a decomposition in two plans based on the energy. The present invention concerns a method of audio compression and decompression, simple, of high quality, not requiring a lot of computations and allowing to obtain very high compression ratios. This codec is optimized for both the voice and the music. The most spread methods nowadays use the Linear Predictive Coding (LPC) in the time domain for the voice and the Modified Discrete Cosine Transform (MDCT) in the frequency domain for the music. The present codec uses the Fast Fourier Transform (FFT). The Fast Fourier Transform buffers are split into a forward plan (composed only of the biggest points) and a backward plan (composed of the most energetic bands). The non null points in the bands are composed only of points not taken into account in the forward plan. For the voice, this codec uses only the magnitudes of the local peaks (without the laterals points) and only the imaginary part in decompression. For the music and all audio signals, it uses the magnitudes and the phases of the points of the forward and backward plans, in compression and in decompression. It can also use only the local peaks with the phases. The edge effects are canceled with the help of a partial overlap method (50% or less) allowing a perfect reconstruction. Efficient methods of coding of magnitudes and phases are used. This codec is intended for all vocal bi-directional communications (voice over IP or mobile phones for instance), for the audio streaming (radios on Internet for instance) as well as for the stocking of audio data (files on hard disk for instance).
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Citations
10 Claims
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1. ) A method of audio compression and decompression comprising
the use of the Fast Fourier Transform (FFT) for the voice and the music and a decomposition in two plans based on the energy.
Specification