Ntt Docomo, Inc.

Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Dolby International Ab

Vesa Ruoppila

Nobuhiko Naka

Guillaume Fuchs

Bernhard Grill

Christian Helmrich

Ralf Geiger

Markus Schnell

Emmanuel Ravelli

Tom Baeckstroem

Tom Bäckström

Tom BÄCKSTRÖM

The purpose of the present invention is to estimate, with a small amount of computation, a linear prediction synthesis filter after conversion of an internal sampling frequency. A linear prediction coefficient conversion device is a device that converts first linear prediction coefficients calculated at a first sampling frequency to second linear prediction coefficients at a second sampling frequency different from the first sampling frequency, which includes a means for calculating, on the real axis of the unit circle, a power spectrum corresponding to the second linear prediction coefficients at the second sampling frequency based on the first linear prediction coefficients or an equivalent parameter, a means for calculating, on the real axis of the unit circle, autocorrelation coefficients from the power spectrum, and a means for converting the autocorrelation coefficients to the second linear prediction coefficients at the second sampling frequency.

Linear prediction coefficient conversion device and linear prediction coefficient conversion method

The present disclosure relates to a method of downmixing a plurality of input audio channels. The method include obtaining, for each of the input audio channels, a plurality of frequency coefficients in a plurality of corresponding frequency bins, and applying, for at least one frequency bin, a downmix matrix to a first array formed by the frequency coefficients of the plurality of input audio channels for the respective frequency bin to obtain a second array formed by the frequency coefficients of a plurality of intermediate audio channels for the respective frequency bin. The method further involves determining a third array including only the non-zero entries of the downmix matrix, and determining a fourth array including, for each entry of the third array, an entry indicative of a position of the respective entry of the third array within the downmix matrix. Applying the downmix matrix to the first array involves multiplying, for the at least one frequency bin, the entries of the third array with corresponding entries of the first array for the respective frequency bin, the corresponding entries of said first array being determined on the basis of the fourth array. The present disclosure further relates to a corresponding apparatus for downmixing a plurality of input audio channels and to a corresponding program storage device configured for downmixing a plurality of input audio channels.

Efficient format conversion in audio coding

An apparatus for encoding an audio signal having a stream of audio samples has: a windower for applying a prediction coding analysis window to the stream of audio samples to obtain windowed data for a prediction analysis and for applying a transform coding analysis window to the stream of audio samples to obtain windowed data for a transform analysis, wherein the transform coding analysis window is associated with audio samples within a current frame of audio samples and with audio samples of a predefined portion of a future frame of audio samples being a transform-coding look-ahead portion, wherein the prediction coding analysis window is associated with at least the portion of the audio samples of the current frame and with audio samples of a predefined portion of the future frame being a prediction coding look-ahead portion, wherein the transform coding look-ahead portion and the prediction coding look-ahead portion are identically to each other or are different from each other by less than 20%; and an encoding processor for generating prediction coded data or for generating transform coded data.

Apparatus and method for encoding and decoding an audio signal using an aligned look-ahead portion

Growing community of inventors

Nuremberg, Germany

Vesa Ruoppila