Google Inc.

Huawei Technologies Co., Limited

Minyue Li

Willem Bastiaan Kleijn

Jan K Skoglund

Janusz Klejsa

Guoqiang Zhang

Henrik Lundin

Alessio Bazzica

Niklas Blum

Tina Le Grand

Michael Tschumi

Alexander Narest

W Bastiaan Kleijn

Provided are methods, systems, and apparatus for hierarchical decorrelation of multichannel audio. A hierarchical decorrelation algorithm is designed to adapt to possibly changing characteristics of an input signal, and also preserves the energy of the original signal. The algorithm is invertible in that the original signal can be retrieved if needed. Furthermore, the proposed algorithm decomposes the decorrelation process into multiple low-complexity steps. The contribution of these steps is generally in a decreasing order, and thus the complexity of the algorithm can be scaled.

Hierarchical decorrelation of multichannel audio

Control logic determines when a network condition has changed by evaluating network condition data. Based on a detected network condition change, the control logic reorders an encoder parameter controller execution sequence of a plurality of encoder parameter controllers. The control logic configures the plurality of reordered encoder parameter controllers so that an encoder parameter determination from a prior encoder parameter controller is used as a decision input for a subsequent encoder parameter controller. An encoder encodes data, such as audio data, video data or other type of data using the generated encoder control parameters from the reordered plurality of encoder parameter controllers. A related method is also disclosed.

Method and device for providing pipeline reordering of encoder parameter controllers for an encoder

Aspects of the disclosure simulate a conversation over a real-time communication system and a reference script shared between the communication devices serves as a basis for comparison against the received speech-recognized conversation. A method of evaluating call quality of a real-time communication system that includes at least two communication devices is disclosed that includes receiving a reference script, the reference script containing linguistic contents of an audio signal being sent to one of the communication devices; generating an evaluation transcript by applying speech recognition to the audio signal being received; comparing the reference script with the evaluation transcript; and generating a call quality metric of the real-time communication system based on the comparison. The call quality metric may also include a communication delay which may be evaluated by determining a duration of a speaking turn; determining a duration of a listening turn from the audio signal being received by one of the communication devices; and estimating a communication delay of the audio signal based on the duration of the speaking turn and the listening turn.

Conversational call quality evaluator

Hierarchical deccorelation of multichannel audio

Provided are methods and systems for rearranging a multichannel audio signal into sub-signals and allocating bit rates among them, such that compressing the sub-signals with a set of audio codecs at the allocated bit rates yields an optimal fidelity with respect to the original multichannel audio signal. Rearranging the multichannel audio signal into sub-signals and assigning each sub-signal a bit rate may be optimized according to a criterion. Existing audio codecs may be used to quantize the sub-signals at the assigned bit rates and the compressed sub-signals may be combined into the original format according to the manner in which the original multichannel audio signal is rearranged.

Rearrangement and rate allocation for compressing multichannel audio

In a method for reconstructing a source signal, which is encoded by a set of at least two descriptions, the method comprises: receiving a subset of the set of descriptions; reconstructing a reconstructed signal at an operating bitrate of a set of operating bitrates upon the basis of the subset of descriptions, the reconstructed signal having a second probability density, wherein the second probability density comprises a first statistical moment and a second statistical moment; and manipulating the reconstructed signal, wherein the reconstructed signal is manipulated such that, irrespective of the operating bitrate, a predetermined minimum similarity between a first statistical moment of a third probability density and a first statistical moment of a first probability density and between a second statistical moment of the third probability density and a second statistical moment of the first probability density is maintained.

Method and decoder for reconstructing a source signal

In a method for reconstructing a source signal, which is encoded by a set of at least two descriptions, the method comprises: receiving a subset of the set of descriptions; reconstructing a reconstructed signal at an operating bitrate of a set of operating bitrates upon the basis of the subset of descriptions, the reconstructed signal having a second probability density, wherein the second probability density comprises a first statistical moment and a second statistical moment; and manipulating the reconstructed signal, wherein the reconstructed signal is manipulated such that, irrespective of the operating bitrate, a predetermined minimum similarity between the first statistical moment of the third probability density and the first statistical moment of the first probability density and between the second statistical moment of the third probability density and the second statistical moment of the first probability density is maintained.

The invention relates to an estimator for estimating a probability distribution of a quantization index generated from a source coder encoding a source signal, into a sequence of quantization indices, the source signal being described by a signal model, the source coder providing a current quantization index and current side information, the estimator being configured to obtain auxiliary parameters based on a configuration of the source coder and the current available side information and the signal model, the estimator being further configured to adaptively update the probability distribution of a quantization index upon the basis of a probability density function relating to a previous state of the estimator, the auxiliary parameters, the current quantization index and the current side information.

Estimator for estimating a probability distribution of a quantization index

Methods and devices for encoding and decoding are provided. A source signal value is encoded by a quantization index determined using a partition into quantization cells. Decoding of the quantization index takes place by sampling a reconstruction probability distribution, thereby obtaining a reconstructed signal value, such that the reconstructed signal value lies in the same quantization cell as the source signal value. In one embodiment, encoding and decoding are such that their succession preserves the source signal distribution. In another embodiment, the partition and the reconstruction probability distribution are determined in such manner that the quantization error is minimized subject to a constraint on the relative entropy between the source signal and the reconstructed signal.

Coding and decoding of source signals using constrained relative entropy quantization

The present invention relates to methods and devices for encoding and decoding digital audio signals, e.g. a speech signal. An audio coder and a decoder are provided wherein a modeller adds a first distribution model obtained from model parameters of past segments of the digital audio signal and a fixed distribution model, each of the models being multiplied by a weighting coefficient, for obtaining a combined distribution model. The weighting coefficients are selected to minimize a code length of a current segment of the digital audio signal. As the combined distribution model is a sum of several distribution models, wherein at least some of the models is based on the model parameters, flexibility is introduced in the signal model used to encode the digital audio signal. Thus, an audio coder and decoder providing a low bit rate in average, low bit rate variations and low error propagation are provided.

Growing community of inventors

Beijing, China

Minyue Li