Methods for audio encoding and decoding, corresponding computer-readable media and corresponding audio encoder and decoder
AssigneeDolby International AB
InventorsHeiko PURNHAGEN, Lars VILLEMOES, Leif Jonas SAMUELSSON, Toni HIRVONEN
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Abstract
The present disclosure provides methods, devices and computer program products which provide less complex and more flexible control of the introduced decorrelation in an audio coding system. According to the disclosure, this is achieved by calculating and using two weighting factors, one for an approximated audio object and one for a decorrelated audio object, for introduction of decorrelation of audio objects in the audio coding system.
Claims21
1-28. (canceled)
A method for reconstructing a time/frequency tile of N audio objects, comprising the steps of:
- receiving M downmix signals;
- receiving a reconstruction matrix enabling reconstruction of an approximation of the N audio objects from the M downmix signals;
- applying the reconstruction matrix to the M downmix signals in order to generate N approximated audio objects;
- subjecting at least a subset of the N approximated audio objects to a decorrelation process in order to generate at least one decorrelated audio object, whereby each of the at least one decorrelated audio object corresponds to one of the N approximated audio objects;
- for each of the N approximated audio objects not having a corresponding decorrelated audio object, reconstructing the time/frequency tile of the audio object by the approximated audio object;
- and
- for each of the N approximated audio objects having a corresponding decorrelated audio object, reconstructing the time/frequency tile of the audio object by:
- receiving a single weighting parameter from which a first weighting factor and a second weighting factor are derivable,
- weighting the approximated audio object by the first weighting factor,
- weighting the decorrelated audio object corresponding to the approximated audio object by the second weighting factor, and
- combining, by performing a summation, the weighted approximated audio object with the corresponding weighted decorrelated audio object for reconstructing the time/frequency tile of the approximated audio object, whereby an energy level of the reconstructed time/frequency tile equals an energy level of a corresponding time/frequency tile of the approximated audio object.
An apparatus for reconstructing a time/frequency tile of N audio objects, comprising:
- a first receiving component configured to receive M downmix signals;
- a second receiving component configure to receive a reconstruction matrix enabling reconstruction of an approximation of the N audio objects from the M downmix signals;
- an audio object approximating component arranged downstreams of the first and second receiving components and configured to apply the reconstruction matrix to the M downmix signals in order to generate N approximated audio objects;
- a decorrelating component arranged downstreams of the audio object approximating component and configured to subject at least a subset of the N approximated audio objects to a decorrelation process in order to generate at least one decorrelated audio object, whereby each of the at least one decorrelated audio object corresponds to one of the N approximated audio objects;
- the second receiving component further configured to receive, for each of the N approximated audio objects having a corresponding decorrelated audio object, a single weighting parameter from which a first weighting factor and a second weighting factor are derivable;
- and
- an audio object reconstructing component arranged downstreams of the audio object approximating component, the decorrelating component, and the second receiving component, and configured to:
- for each of the N approximated audio objects not having a corresponding decorrelated audio object, reconstruct the time/frequency tile of the audio object by the approximated audio object;
- and
- for each of the N approximated audio objects having a corresponding decorrelated audio object, reconstruct the time/frequency tile of the audio object by:
- weighting the approximated audio object by the first weighting factor;
- weighting the decorrelated audio object corresponding to the approximated audio object by the second weighting factor;
- and
- combining, by performing a summation, the weighted approximated audio object with the corresponding weighted decorrelated audio object for reconstructing the time/frequency tile of the approximated audio object, whereby an energy level of the reconstructed time/frequency tile equals an energy level of a corresponding time/frequency tile of the approximated audio object.
A method in an encoder for generating at least one weighting parameter, to be used when reconstructing a time/frequency tile of a specific audio object the method comprising the steps of:
- receiving M downmix signals being combinations of at least N audio objects including the specific audio object;
- receiving the specific audio object;
- calculating a first quantity indicative of an energy level of the specific audio object;
- calculating a second quantity indicative of an energy level corresponding to an energy level of an encoder side approximation of the specific audio object, the encoder side approximation being a combination of the M downmix signals;
- calculating at least one weighting parameter based on the first and the second quantity, wherein the at least one weighting parameter is for weighting a decoder side approximation of the specific audio object and a decorrelated version of the decoder side approximation of the specific audio object.
The method according to 40, wherein the at least one weighting parameter comprises a single weighting parameter from which a first weighting factor and a second weighting factor is derivable, the first weighting factor for weighting of the decoder side approximation of the specific audio object and the second weighting factor for weighting the decorrelated version of the decoder side approximated audio object.
An encoder for generating at least one weighting parameter to be used when reconstructing a time/frequency tile of a specific audio object the apparatus comprising:
- a receiving component configured to receive M downmix signals being combinations of at least N audio objects including the specific audio object, the receiving component further configured to receive the specific audio object;
- a calculating unit configured to:
- calculate a first quantity indicative of an energy level of the specific audio object;
- calculate a second quantity indicative of an energy level corresponding to an energy level of an encoder side approximation of the specific audio object, the encoder side approximation being a combination of the M downmix signals;
- calculating the at least one weighting parameter based on the first and the second quantity, wherein the at least one weighting parameter is for weighting a decoder side approximation of the specific audio object and a decorrelated version of the decoder side approximation of the specific audio object.
Dependencies are inferred from the claim text.