Stereo Audio Encoding with Overlap Pre-Encoding for Delay Alignment
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Solution Overview
Problem
The existing embedded encoding/decoding technologies for sound signals with multiple channels and monaural signals result in a larger algorithmic delay for stereo encoding/decoding compared to monaural encoding/decoding, complicating control in systems like multipoint control units for conference calls.
Innovation Solution
A sound signal encoding method that includes a stereo encoding step, a downmix step, and a monaural encoding step, with an additional encoding of a section corresponding to the overlap between frames to obtain an additional code, ensuring the algorithmic delay of stereo encoding/decoding is not larger than that of monaural encoding/decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a monaural encoding/decoding scheme with window overlap processing is used for embedded encoding/decoding, then the monaural decoding quality is improved, but the algorithmic delay of stereo encoding/decoding becomes larger than that of monaural encoding/decoding
Solution Approach 1:
The patent applies preliminary action by performing encoding of the overlap section in advance during the current frame processing. The encoder encodes a portion of the downmix signal corresponding to the overlap section between the current frame and the immediately following frame, and outputs an additional code. This allows the decoder to have the additional decoded signal ready before it is actually needed for stereo decoding, thereby eliminating the additional delay that would otherwise occur when the overlap section encoding is performed separately after monaural decoding.
2Adaptability or versatility
If stereo decoding is performed after monaural decoding with window overlap, then embedded encoding/decoding functionality is achieved, but control complexity in multipoint systems increases
Solution Approach 1:
By encoding the overlap section in advance and outputting an additional code, the patent eliminates the need for complex delay compensation mechanisms in multipoint control units. The decoder outputs an additional decoded signal that can be directly used for stereo decoding without requiring additional buffering or delay adjustment, thereby simplifying the control logic in multipoint conference call systems.
3Loss of time
If additional encoding of overlap section is performed, then the algorithmic delay of stereo encoding/decoding matches that of monaural encoding/decoding, but the encoding complexity increases
Solution Approach 1:
The patent segments the downmix signal encoding into two distinct parts: the main downmix signal encoding and the overlap section encoding. The encoder performs standard monaural encoding on the downmix signal to obtain a monaural code, and separately encodes only the overlap section portion to obtain an additional code. This segmentation allows the system to achieve delay alignment without requiring complete re-encoding of the entire signal, thereby limiting the increase in encoding complexity to only the overlap section processing.
Data Source
AI summary
There is provided such embedded encoding that the algorithmic delay of stereo coding/decoding is not larger than that of monaural coding/decoding. An encoding device (100) encodes a sound signal having a plurality of channels. A stereo encoding unit (110) obtains and outputs a stereo code representing a characteristic of difference between channels of the sound signal. A downmix unit (150) obtains a signal by mixing the sound signal as a downmix signal. A monaural encoding unit (120) encodes the downmix signal by an encoding scheme that includes processing of applying a window having overlap between frames to obtain and output a monaural code. An additional encoding unit (130) encodes a part of the downmix signal for a section corresponding to the overlap between a current frame and an immediately following frame to obtain and output an additional code.