Hierarchical audio coding, decoding method and system
First Claim
1. A hierarchical audio coding method, comprising following steps:
- dividing frequency domain coefficients of an audio signal for which Modified Discrete Cosine Transform (MDCT) has been performed into core layer frequency domain coefficients and extended layer frequency domain coefficients, and dividing the core layer frequency domain coefficients and extended layer frequency domain coefficients into a plurality of coding sub-bands, and quantizing and coding amplitude envelope values of the coding sub-bands;
allocating bits to each coding sub-band of a core layer according to the amplitude envelope value of each coding sub-band of the core layer, and then quantizing and coding the core layer frequency domain coefficients to obtain coded bits of the core layer frequency domain coefficients;
calculating an amplitude envelope value of each coding sub-band of a core layer residual signal according to the amplitude envelope value and a bit allocation number of each coding sub-band of the core layer;
allocating bits to each coding sub-band of an extended layer according to an extended layer coding signal composed of the core layer residual signal and the extended layer frequency domain coefficients and the amplitude envelope value of each coding sub-band composed of the extended layer coding signal, and then quantizing and coding the extended layer coding signal to obtain coded bits of the extended layer coding signal; and
multiplexing and packing amplitude value envelope coded bits of each coding sub-band composed of the core layer frequency domain coefficients and the extended layer frequency domain coefficients, coded bits of the core layer frequency domain coefficients, and coded bits of the extended layer coding signal, and then transmitting to a decoding end.
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Abstract
A hierarchical audio coding, decoding method and system are provided. The method includes dividing frequency domain coefficients of an audio signal after MDCT into a plurality of coding sub-bands, quantizing and coding amplitude envelope values of coding sub-bands; allocating bits to each coding sub-band of the core layer, quantizing and coding core layer frequency domain coefficients to obtain coded bits of core layer frequency domain coefficients; calculating the amplitude envelope value of each coding sub-band of the core layer residual signal; allocating bits to each coding sub-band of the extended layer, quantizing and coding the extended layer coding signal to obtain coded bits of the extended layer coding signal; multiplexing and packing amplitude value envelope coded bits of each coding sub-band composed by core layer and extended layer frequency domain coefficients, core layer frequency coefficients coded bits, and extended layer coding signal coded bits, then transmitting to the decoding end.
31 Citations
22 Claims
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1. A hierarchical audio coding method, comprising following steps:
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dividing frequency domain coefficients of an audio signal for which Modified Discrete Cosine Transform (MDCT) has been performed into core layer frequency domain coefficients and extended layer frequency domain coefficients, and dividing the core layer frequency domain coefficients and extended layer frequency domain coefficients into a plurality of coding sub-bands, and quantizing and coding amplitude envelope values of the coding sub-bands; allocating bits to each coding sub-band of a core layer according to the amplitude envelope value of each coding sub-band of the core layer, and then quantizing and coding the core layer frequency domain coefficients to obtain coded bits of the core layer frequency domain coefficients; calculating an amplitude envelope value of each coding sub-band of a core layer residual signal according to the amplitude envelope value and a bit allocation number of each coding sub-band of the core layer; allocating bits to each coding sub-band of an extended layer according to an extended layer coding signal composed of the core layer residual signal and the extended layer frequency domain coefficients and the amplitude envelope value of each coding sub-band composed of the extended layer coding signal, and then quantizing and coding the extended layer coding signal to obtain coded bits of the extended layer coding signal; and multiplexing and packing amplitude value envelope coded bits of each coding sub-band composed of the core layer frequency domain coefficients and the extended layer frequency domain coefficients, coded bits of the core layer frequency domain coefficients, and coded bits of the extended layer coding signal, and then transmitting to a decoding end. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A hierarchical audio decoding method, comprising following steps:
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de-multiplexing a bit stream sent by a coding end, and decoding amplitude envelope coded bits of core layer frequency domain coefficients to obtain an amplitude envelope value of each coding sub-band of a core layer; allocating bits to each sub-band of the core layer according to the amplitude envelope value of each coding sub-band of the core layer, and calculating an amplitude envelope value of a core layer residual signal;
decoding amplitude envelope coded bits of extended layer frequency domain coefficients to obtain an amplitude envelope value of the extended layer frequency domain coefficients;
allocating bits to each coding sub-band of an extended layer according to the amplitude envelope value of the core layer residual signal and amplitude envelope value of the extended layer frequency domain coefficients; andrespectively decoding coded bits of the core layer frequency domain coefficients and coded bits of an extended layer coding signal according to a bit allocation number of the core layer and a bit allocation number of the extended layer to obtain the core layer frequency domain coefficients and the extended layer coding signal, rearranging the extended layer coding signal according to an order of frequency bands and adding with the core layer frequency domain coefficients to obtain frequency domain coefficients of a whole bandwidth, performing inverse Modified Discrete Cosine Transform (IMDCT) on the frequency domain coefficients of the whole bandwidth to obtain an output audio signal. - View Dependent Claims (13, 14, 15)
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16. A hierarchical audio coding system, comprising:
- a Modified Discrete Cosine Transform (MDCT) unit, an amplitude envelope calculating unit, an amplitude envelope quantizing and coding unit, a core layer bit allocating unit, a core layer frequency domain coefficient vector quantizing and coding unit, and a bit stream multiplexer;
the system further comprises;
an extended layer coding signal generating unit, a residual signal amplitude envelope generating unit, an extended layer bit allocating unit, and an extended layer coding signal vector quantizing and coding unit;
wherein;the MDCT unit is configured to perform Modified Discrete Cosine Transform on an input audio signal to generate core layer frequency domain coefficients and extended layer frequency domain coefficients; the amplitude envelope calculating unit is configured to group to-be-coded parts in the core layer frequency domain coefficients and extended layer frequency domain coefficients as core layer frequency domain coefficient coding sub-bands and extended layer frequency domain coefficient coding sub-bands, and calculate an amplitude envelope value of each coding sub-band; the amplitude envelope quantizing and coding unit is configured to quantize and code the amplitude envelope values of the core layer frequency domain coefficient coding sub-bands and extended layer frequency domain coefficient coding sub-bands to generate an amplitude envelope quantization exponent and coded bits of amplitude envelope of each coding sub-band of the core layer frequency domain coefficients and the extended layer frequency domain coefficients; the core layer bit allocating unit is configured to allocate bits to the core layer to obtain a bit allocation number of each coding sub-band of the core layer; the core layer frequency domain coefficient vector quantizing and coding unit is configured to normalize, vector quantize and code the frequency domain coefficients of each coding sub-band of the core layer using a quantization amplitude envelope value and bit allocation number of each coding sub-band of the core layer reconstructed according to the amplitude envelope quantization exponent of each coding sub-band of the core layer to obtain coded bits of the core layer frequency domain coefficients; the extended layer coding signal generating unit is configured to generate a residual signal, and obtain an extended layer coding signal composed of the residual signal and extended layer frequency domain coefficients; the residual signal amplitude envelope generating unit is configured to obtain an amplitude envelope quantization exponent of each coding sub-band of the residual signal according to an amplitude envelope quantization exponent of each coding sub-band of the core layer and a bit allocation number of a corresponding coding sub-band; the extended layer bit allocating unit is configured to allocate bits to an extended layer according to the amplitude envelope quantization exponent of each coding sub-band of the residual signal and the amplitude envelope quantization exponent of each coding sub-band of the extended layer frequency domain coefficients to obtain a bit allocation number of each coding sub-band of the extended layer coding signal; the extended layer coding signal vector quantizing and coding unit is configured to normalize, vector quantize and code the coding signal of each coding sub-band of the extended layer using a quantization amplitude envelope value and bit allocation number of each coding sub-band of the extended layer reconstructed according to the amplitude envelope quantization exponent of each coding sub-band of the extended layer to obtain coded bits of the extended layer coding signal; the bit stream multiplexer is configured to pack side information bits of the core layer, the coded bits of the amplitude envelope of each coding sub-band of the core layer, the coded bits of the core layer frequency domain coefficients, side information bits of the extended layer, the coded bits of each amplitude envelope of the extended layer frequency domain coefficients, and the coded bits of the extended layer coding signal. - View Dependent Claims (17, 18, 19)
- a Modified Discrete Cosine Transform (MDCT) unit, an amplitude envelope calculating unit, an amplitude envelope quantizing and coding unit, a core layer bit allocating unit, a core layer frequency domain coefficient vector quantizing and coding unit, and a bit stream multiplexer;
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20. A hierarchical audio decoding system, comprising:
- a bit stream de-multiplexer, a core layer amplitude envelope decoding unit, a core layer bit allocating unit, and a core layer decoding and inverse quantizing unit;
the system further comprises;
an extended layer amplitude envelope decoding unit, a core layer residual signal amplitude envelope generating unit, an extended layer bit allocating unit, an extended layer coding signal decoding and inverse quantizing unit, a frequency domain coefficient generating unit, a noise filling unit and an inverse Modified Discrete Cosine Transform (IMDCT) unit;
wherein;the core layer amplitude envelope decoding unit is configured to decode amplitude envelope coded bits of coding sub-bands of a core layer output by the bit stream de-multiplexer to obtain an amplitude envelope quantization exponent of each coding sub-band of the core layer; the core layer bit allocating unit is configured to allocate bits to the core layer to obtain a bit allocation number of each coding sub-band of the core layer; the core layer decoding and inverse quantizing unit is configured to calculate a quantization amplitude envelope value of each coding sub-band of the core layer according to the amplitude envelope quantization exponent of each coding sub-band of the core layer, and decode, inversely quantize and inversely normalize the coded bits of the core layer frequency domain coefficients output by the bit stream de-multiplexer using the bit allocation number and the quantization amplitude envelope value of each coding sub-band of the core layer to obtain the core layer frequency domain coefficients; the extended layer amplitude envelope decoding unit is configured to decode the amplitude envelope coded bits of the core layer frequency domain coefficients output by the bit stream de-multiplexer to obtain an amplitude envelope quantization exponent of each coding sub-band of the core layer frequency domain coefficients; the core layer residual signal amplitude envelope generating unit is configured to calculate an amplitude envelope quantization exponent of each coding sub-band of the residual signal according to the amplitude envelope quantization exponent of each coding sub-band of the core layer and the bit allocation number of a corresponding coding sub-band; the extended layer bit allocating unit is configured to allocate bits to an extended layer according to the amplitude envelope quantization exponent of each coding sub-band of the residual signal and the amplitude envelope quantization exponent of each coding sub-band of the extended layer frequency domain coefficients to obtain a bit allocation number of each coding sub-band of the extended layer coding signal; the extended layer coding signal decoding and inverse quantizing unit is configured to calculate a quantization amplitude envelope value of each coding sub-band of the extended layer using the amplitude envelope quantization exponent of each coding sub-band of the extended layer, and decode, inversely quantize and inversely normalize the coded bits of the extended layer coding signal output by the bit stream de-multiplexer using the bit allocation number and the quantization amplitude envelope value of each coding sub-band of the extended layer to obtain the extended layer coding signal; the frequency domain coefficient generating unit is configured to reorder the extended layer coding signal output by the extended layer coding signal decoding and inverse quantizing unit according to an order of the frequency bands, and then perform sum calculation with the core layer frequency domain coefficients output by the core layer coding signal decoding and inverse quantizing unit to obtain frequency domain coefficient output values; the noise filling unit is configured to perform noise filling on the coding sub-bands to which no coded bit is allocated during a process of coding; the IMDCT unit is configured to perform IMDCT on all frequency domain coefficients for which noise filling has been performed to obtain an output audio signal. - View Dependent Claims (21, 22)
- a bit stream de-multiplexer, a core layer amplitude envelope decoding unit, a core layer bit allocating unit, and a core layer decoding and inverse quantizing unit;
Specification