AUDIO DECODER WITH CORE DECODER AND SURROUND DECODER
First Claim
1. A method performed in an audio decoder for reconstructing N audio channels from M audio channels, the method comprising:
- receiving an encoded audio bitstream, the encoded audio bitstream including a downmixed audio signal and surround data, the downmixed audio signal having M audio channels and the surround data including a set of spatial parameters, the set of spatial parameters including at least one inter-channel intensity difference parameter and at least one inter-channel coherence parameter;
decoding, in a surround data decoder, the surround data to produce decoded surround data;
decoding, in a core decoder, the downmixed audio signal having M audio channels to obtain a decoded frequency domain representation of the M audio channels, wherein the decoded frequency domain representation of the M audio channels includes a plurality of frequency bands, and each frequency band includes one or more spectral components;
reconstructing, in a surround decoder, a frequency domain representation of the N audio channels from the decoded frequency domain representation of the M audio channels, mode information used to select one of a plurality of different mixing schemes, and the decoded surround data; and
synthesizing, with one or more synthesis filterbanks, the frequency domain representation of the N audio channels to create a time domain representation of the N audio channels;
wherein M is one or more, M is less than N, the audio decoder is implemented at least in part with hardware, and the reconstructing includes generating a decorrelated signal using an all-pass filter.
1 Assignment
0 Petitions
Accused Products
Abstract
A method performed by an audio decoder for reconstructing N audio channels from an audio signal containing M audio channels is disclosed. The method includes receiving a bitstream containing an encoded audio signal having M audio channels and a set of spatial parameters, the set of spatial parameters including an inter-channel intensity difference parameter and an inter-channel coherence parameter. The encoded audio bitstream is then decoded to obtain a decoded frequency domain representation of the M audio channels, and at least a portion of the frequency domain representation is decorrelated with an all-pass filter having a fractional delay. The all-pass filter is attenuated at locations of a transient. A matrixed version of the decorrelated signals are summed with a matrixed version of the decoded frequency domain representation to obtain N audio signals that collectively having N audio channels where M is less than N.
-
Citations
14 Claims
-
1. A method performed in an audio decoder for reconstructing N audio channels from M audio channels, the method comprising:
-
receiving an encoded audio bitstream, the encoded audio bitstream including a downmixed audio signal and surround data, the downmixed audio signal having M audio channels and the surround data including a set of spatial parameters, the set of spatial parameters including at least one inter-channel intensity difference parameter and at least one inter-channel coherence parameter; decoding, in a surround data decoder, the surround data to produce decoded surround data; decoding, in a core decoder, the downmixed audio signal having M audio channels to obtain a decoded frequency domain representation of the M audio channels, wherein the decoded frequency domain representation of the M audio channels includes a plurality of frequency bands, and each frequency band includes one or more spectral components; reconstructing, in a surround decoder, a frequency domain representation of the N audio channels from the decoded frequency domain representation of the M audio channels, mode information used to select one of a plurality of different mixing schemes, and the decoded surround data; and synthesizing, with one or more synthesis filterbanks, the frequency domain representation of the N audio channels to create a time domain representation of the N audio channels; wherein M is one or more, M is less than N, the audio decoder is implemented at least in part with hardware, and the reconstructing includes generating a decorrelated signal using an all-pass filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. An audio decoder for reconstructing N audio channels from M audio channels, the audio decoder comprising:
-
an input interface for receiving an encoded audio bitstream, the encoded audio bitstream including a downmixed audio signal and surround data, the downmixed audio signal having M audio channels and the surround data including a set of spatial parameters, the set of spatial parameters including at least one inter-channel intensity difference parameter and at least one inter-channel coherence parameter; a surround data decoder for decoding the surround data to produce decoded surround data; a core decoder for decoding the downmixed audio signal having M audio channels to obtain a decoded frequency domain representation of the M audio channels, wherein the decoded frequency domain representation of the M audio channels includes a plurality of frequency bands, and each frequency band includes one or more spectral components; a surround decoder for reconstructing a frequency domain representation of the N audio channels from the decoded frequency domain representation of the M audio channels, mode information used to select one of a plurality of different mixing schemes, and the decoded surround data; and one or more synthesis filterbanks for synthesizing the frequency domain representation of the N audio channels to create a time domain representation of the N audio channels, wherein M is one or more and M is less than N and the surround decoder includes an all-pass filter for generating a decorrelated signal.
-
Specification