High efficiency digital data encoding and decoding apparatus

Abstract From the Canadian patent

An apparatus for compressing a digital input signal compresses a digital input signal, arranged into frames of plural samples. The digital input signal is orthogonally transformed by, plural orthogonal transform circuits in blocks derived by dividing the frames by a different, divisor in each circuit. The resulting spectral coefficients are quantized using an adaptive number, of bits. The output of one orthogonal transform circuit is selected based on the outputs of the, orthogonal transform circuits. The digital input signal is divided into plural frequency ranges, and, frames are formed in each range. A block length decision circuit determines division of the, frames of each range …