US 7,024,259 B1Granted

System and method for evaluating the quality of multi-channel audio signals

AssigneeFraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.

InventorsThomas Sporer, Roland Bitto, Karlheinz Brandenburg

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Abstract

A system for evaluating the quality of an audio test signal derived from an audio reference signal by coding and decoding, said audio test signal and said audio reference signal each comprising a plurality of channels, comprises a unit for converting the audio reference signal into a first audio reference sum signal at a first reference point and into a second audio reference sum signal at a second reference point and for converting the audio test signal into a first audio test sum signal at the first reference point and into a second audio test sum signal at the second reference point, the audio reference sum signals and the audio test sum signals at the first and second reference points being a superposition of the respective channels, which can be emitted by a plurality of loudspeakers, weighted with a respective transfer function between the respective loudspeaker and the reference point in question, and a unit for evaluating the quality of the audio test sum signals while taking into consideration the audio reference sum signals so as to provide an indication of the quality of the audio test signal. The system according to the present invention permits real rooms and an arbitrary number of channels of the audio test signal to be taken into account so as to execute a listening-adapted evaluation of the quality of a specific coding/decoding method.

Claims21

Dependent claims

A system for evaluating the quality of an audio test signal derived from an audio reference signal by coding and decoding, said audio test signal and said audio reference signal each comprising a plurality of channels, each channel being adapted to be made audible by one loudspeaker of a plurality of loudspeakers which are positioned at different positions in an at least fictitious room, and two listening reference points being defined with respect to the positions of the plurality of loudspeakers, said system comprising:

a unit for converting the audio reference signal into a first audio reference sum signal at the first reference point and into a second audio reference sum signal at the second reference point and for converting the audio test signal into a first audio test sum signal at the first reference point and into a second audio test sum signal at the second reference point, wherein the first and the second reference points are different from each other,
wherein the unit for converting includes:
a weighting device for weighting each channel using a respective transfer function between the respective loudspeaker and the reference point in question to obtain weighted channels, and
an adding device for each reference point, the adding device for the first reference point being adapted to add weighted channels generated using transfer functions between the loudspeakers and the first reference point, and the adding device for the second reference point being adapted to add weighted channels generated using transfer functions between the loudspeakers and the second reference point so as to obtain an audio reference sum signal and an audio test sum signal for each reference point;
and
a unit for evaluating the quality of the audio test sum signals output by the adding devices while taking into consideration the audio reference sum signals output by the adding devices so as to provide an indication of the quality of the audio test signal.

3 more elements

A method for evaluating the quality of an audio test signal derived from an audio reference signal by coding and decoding, said audio test signal and said audio reference signal each comprising a plurality of channels, each channel being adapted to be made audible by one loudspeaker of a plurality of loudspeakers which are positioned at different positions in an at least fictitious room, and two reference points being defined with respect to the positions of the plurality of loudspeakers, said method comprising the following steps:

converting the audio reference signal into a first audio reference sum signal at the first reference point and into a second audio reference sum signal at the second reference point, wherein the first and the second reference points are different from each other;
converting the audio test signal into a first audio test sum signal at the first reference point and into a second audio test sum signal at the second reference point;
the step of converting including
a step of weighting the each channels, which is emittable by said plurality of loudspeakers, using a respective transfer function between the respective loudspeaker and the reference point in question;
and
a step of adding weighted channels generated using transfer functions between the loudspeakers and the first reference point and a step of adding weighted channels generated using transfer functions between the loudspeakers and the second reference point so as to obtain an audio reference sum signal and an audio test sum signal for each reference point;
and
conducting the audio test sum signals and the audio reference sum signals to a unit for evaluating the quality of the audio test sum signals while taking into consideration the audio reference sum signals so as to obtain an indication of the quality of the audio test signal.

5 more elements

Dependencies are inferred from the claim text.