Audio Codec Switching Using INTMDCT for Real-Time Noise-Free Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for switching between lossy and lossless audio codecs are complex, require time-frequency domain transforms, and cannot be implemented in real time, leading to high overheads and perceived noise.
Innovation Solution
Implement switching between lossy and lossless codecs by using integer window time domain aliasing cancellation (INT winTDAC) and modified discrete cosine transform (MDCT/IMDCT) within frequency domain encoders and decoders, allowing direct transforms without type conversions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional switching methods between lossy and lossless codecs are used, then switching can be implemented, but the process becomes complex and cannot be performed in real time with high overheads
Solution Approach 1:
The patent changes the fundamental parameter of codec architecture by making both lossy and lossless codecs frequency domain codecs using MDCT/INTMDCT transforms. This parameter change eliminates the need for time-frequency domain conversion during switching, enabling real-time switching with low complexity and overhead
Solution Approach 2:
The patent applies homogeneity by making both lossy and lossless codecs use the same frequency domain architecture and MDCT-based transform. This homogeneous design allows seamless switching between codecs without requiring complex domain conversions, directly resolving the contradiction between switching speed and process complexity
2Reliability
If time-frequency domain transform is performed during codec switching, then domain conversion can be achieved, but overheads increase and perceived noise is introduced
Solution Approach 1:
The patent changes the operational parameter from time-frequency domain conversion to pure frequency domain processing. Both codecs use MDCT transforms, eliminating the need for time-frequency domain conversion during switching. This reduces computational overhead and avoids introducing perceived noise, simultaneously improving reliability and reducing energy loss
3Manufacturing precision
If lossless codec is used for high quality audio, then audio quality improves, but data transmission size increases beyond Bluetooth channel limitations
Solution Approach 1:
The patent applies parameter changes by using frequency domain MDCT transforms for both lossless and lossy encoding. This allows the system to achieve high encoding precision through intelligent parameter control while maintaining data compression efficiency suitable for Bluetooth transmission, resolving the contradiction between audio quality and data size
Data Source
AI summary
A method and an apparatus for switching between a lossy codec and a lossless codec are provided. The method includes: obtaining a waveform of a previous frame Ti−1, and updating the waveform of the previous frame Ti−1 to an input frame buffer in the lossless codec, where the waveform of the previous frame Ti−1 is encoded by a lossy encoder; performing integer window time domain aliasing cancellation INT winTDAC on a waveform in a lossless encoder buffer to obtain a first transform result, and updating the first transform result to an overlapped buffer in the lossless codec; obtaining a waveform of a current frame Ti, and updating the waveform of the current frame Ti to the input frame buffer; and performing integer modified discrete cosine transform INTMDCT on the waveform in the lossless encoder buffer to obtain a second transform result.