Patent ID: 9570080
Date: 2017-02-14
CPC Classifications: G10L,H03M,H04S

Claim:
1. An apparatus for encoding a multi-channel audio signal, the apparatus comprising: a receiver for receiving the multi-channel audio signal, the multi-channel audio signal comprising a first audio signal from a first microphone and a second audio signal from a second microphone; a time-difference unit for determining an inter-time difference between the first audio signal and the second audio signal by combining successive observations of cross correlations between the first audio signal and the second audio signal for a plurality of time offsets for determining the inter-time difference in response to the cross correlations and where the cross-correlations are processed to derive probabilities that are accumulated using a modified Viterbi algorithm; a delay unit for generating a compensated multi-channel audio signal from the multi-channel audio signal by delaying at least one of the first audio signal and the second audio signal in response to the inter-time difference signal; a mono unit for generating a mono signal by combining channels of the compensated multi-channel audio signal; a mono signal encoder for encoding the mono signal; and an output multiplexer for multiplexing the encoded mono signal and data representing the inter-time difference, wherein the time difference unit comprises; a trellis state machine having a plurality of states, each of the plurality of states corresponding to a time offset of the plurality of time offsets; a path unit for determining path metrics for states of the trellis state machine in response to the cross correlations; a probability unit for determining state probability metrics for the states in response to path metrics associated with paths from previous states to current states; and a unit for determining the inter-time difference in response to the state probability metrics.