Bitstream Syntax for Spatial Voice Coding

摘要

An encoding system (100) encodes a first (E1) and further (E2, E3) audio signals as a layered bitstream (B), wherein a quantizer for each frequency band of each signal is selected using a rate allocation rule based on signal-specific rate allocation data, a spectral envelope of the signal and a reference level (EnvE1Max), which is determined based on the spectral envelope of the first signal and is not necessarily included in the bitstream. Further disclosed is a decoding system for reconstructing the audio signals based on the bitstream. In embodiments, the bitstream has a basic layer (BE1), which contains data that enable decoding of the first audio signal, and a spatial layer (Bspatial) facilitating decoding of the further audio signal(s). In embodiments, the encoding system prepares the bitstream subject to a basic-layer bitrate constraint and a total bitrate constraint.

主权项

1. A scalable adaptive audio encoding system, comprising:
an envelope analyzer for outputting spectral envelopes on the basis of a time frame of a frequency-domain representation of a first audio signal (E1) and at least one further audio signal (E2, E3); a multichannel encoder including: a rate allocation component (for determining: first rate allocation data indicating, in a collection of predefined quantizers, quantizers for respective frequency bands of the first audio signal; and second rate allocation data indicating, in a collection of predefined quantizers, quantizers for respective frequency bands of the at least one further audio signal; and a quantization component configured to retrieve the quantizers indicated by the rate allocation component and to quantize the first audio signal and the at least one further audio signal using the quantizers thus retrieved, and to output signal data; and a multiplexer for outputting a bitstream (B) comprising the spectral envelopes, the signal data and the rate allocation data, wherein the rate allocation component is configured with a first rate allocation rule (R1), by which the first rate allocation data, the spectral envelope of the first audio signal (EnvE1) and a reference level (EnvE1Max) derived from the spectral envelope of the first audio signal using a predefined non-zero functional determine the quantizers for the first audio signal, and with a second rate allocation rule (R2), by which the second rate allocation data, the spectral envelope of the at least one further audio signal (EnvE2, EnvE3) and said reference level (EnvE1Max) derived from the first audio signal determine the quantizers for the at least one further audio signal.