Stereo Signal Encoding And Decoding With Delay Interpolation
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Solution Overview
Problem
Existing time-domain stereo encoding and decoding technologies suffer from deviations in inter-channel time differences between the decoded stereo signal and the original stereo signal due to encoding and decoding delays, affecting the accuracy of the stereo sound image.
Innovation Solution
Perform interpolation processing on the inter-channel time difference in the current frame and the previous frame to adjust the delay, using predefined interpolation coefficients based on encoding and decoding delays and frame length, and transmit the adjusted inter-channel time difference to the decoding end for accurate delay alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-domain stereo encoding and decoding is performed using conventional methods, then the encoding and decoding processes can be completed, but there is a deviation between the inter-channel time difference of the decoded stereo signal and the original stereo signal due to encoding and decoding delays
Solution Approach 1:
The patent applies preliminary action by estimating the encoding and decoding delay in advance and using this estimated delay to perform interpolation on the inter-channel time difference before decoding. Specifically, the decoder estimates the delay value based on frame length and sampling rate, then uses this pre-estimated delay to interpolate the inter-channel time difference parameter from the bitstream, thereby compensating for the delay effect before the actual decoding process occurs.
Solution Approach 2:
The patent changes the parameter of inter-channel time difference by performing interpolation processing on this parameter. The decoder retrieves the inter-channel time difference from the bitstream and applies interpolation using the estimated delay to adjust this parameter, thereby transforming it into a compensated value that accounts for encoding and decoding delays, improving the accuracy of the final stereo signal reconstruction.
2Reliability
If the inter-channel time difference is directly used from the bitstream without interpolation, then the decoding process is simpler, but the stereo sound image accuracy is affected due to delay deviation
Solution Approach 1:
The patent performs preliminary estimation of the encoding and decoding delay before the actual interpolation process. The decoder calculates the delay value in advance based on known parameters (frame length, sampling rate), then uses this pre-calculated delay to determine the interpolation factor for adjusting the inter-channel time difference, thereby preparing the compensation mechanism before processing the audio data.
Solution Approach 2:
The patent introduces an intermediary element - the estimated delay value - that mediates between the raw inter-channel time difference from the bitstream and the final compensated value. This delay estimate acts as a mediator that enables the interpolation process, allowing the system to transform the inaccurate direct value into an accurate compensated value while maintaining a relatively simple decoding structure.
Data Source
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AI summary
This application provides an encoding method, a decoding method, an encoding apparatus, and a decoding apparatus for a stereo signal. The encoding method for a stereo signal includes: determining an inter-channel time difference in a current frame; performing interpolation processing based on the inter-channel time difference in the current frame and an inter-channel time difference in a previous frame of the current frame; performing delay alignment on a stereo signal in the current frame based on the inter-channel time difference in the current frame, to obtain a stereo signal after the delay alignment in the current frame; performing time-domain downmixing processing on the stereo signal after the delay alignment in the current frame, to obtain a primary-channel signal and a secondary-channel signal in the current frame; quantizing an inter-channel time difference after the interpolation processing in the current frame, and writing a quantized inter-channel time difference into a bitstream; and quantizing the primary-channel signal and the secondary-channel signal in the current frame, and writing a quantized primary-channel signal and a quantized secondary-channel signal into the bitstream. According to this application, a deviation between an inter-channel time difference of a stereo signal that is finally obtained by decoding and an inter-channel time difference in an original stereo signal can be reduced.