Method to generate multi-channel audio signals from stereo signals

Abstract

A perceptually motivated spatial decomposition for two-channel stereo audio signals, capturing the information about the virtual sound stage, is proposed. The spatial decomposition allows to re-synthesize audio signals for playback over other sound systems than two-channel stereo. With the use of more front loudspeakers, the width of the virtual sound stage can be increased beyond + / - 30 DEG and the sweet spot region is extended. Optionally, lateral independent sound components can be played back separately over loudspeakers on the two sides of a listener to increase listener envelopment. It is also explained how the spatial decomposition can be used with surround sound and wavefield synthesis based audio system. According to the main embodiment of the invention applying to multiple audio signals, it is proposed to generate multiple output audio signals (y1,..., yM) from multiple input audio signals (x1, ..., xL), in which the number of output is equal or higher than the number of input signals , this method comprising the steps of: by means of linear combinations of the input subbands (X1(i), ..., XL(i)), computing one or more independent sound subbands representing signal components which are independent between the input subbands, by means of linear combinations of the input subbands (X1(i), ..., XL(i)), computing one or more localized direct sound subbands representing signal components which are contained in more than one of the input subbands and direction factors representing the ratios with which these signal components are contained in two or more input subbands, generating the output subband signals (Y1(i)...YM(i)), where each output subband signal is a linear combination of the independent sound subbands and the localized direct sound subbands, converting the output subband signals (Y1(i)...YM(i)), to time domain audio signals (y1,..., yM).

Description

Background technique [0001] Many technological innovations beyond binaural stereo have failed because of cost, impracticality (eg, number of speakers), and last but not least the requirement for backward compatibility. And the 5.1 surround multi-channel audio system is being widely adopted by users. In addition, this system is limited in terms of the number of speakers and due to backward compatibility limitations (the front left and right speakers are placed at the same angle as the two-channel stereo above, i.e. + / -30°, resulting in a narrow frontal virtual sound level) is a compromise. [0002] The fact is that further most audio content is available in binaural stereo format. For an audio system that enhances the sound experience beyond stereo, it is therefore crucial that stereo audio content can be desirably played with an improved experience compared to conventional systems. [0003] Furthermore, using more front speakers to improve the virtual sound level has long be...

AI Technical Summary

Problems solved by technology

However, these technical improvements over conventional stereo playback are not clear enough, and they have been widely used

The main limitation of these techniques is that they only consider location and do not explicitly take into account other aspects such as surroundings and listener envelopes

Furthermore, the location theory behind these techniques is based on a virtual source situation, which also limits its performance when many sources appear simultaneously in different directions

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