Audio Downmix Dynamic-Range Control With Saturation-Based Gain Adjustment
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Solution Overview
Problem
Existing audio encoding technologies, such as Dolby Digital and DTS, require complex mathematical processes and significant computational resources due to their destructive compression methods, making them costly and inefficient for achieving high-fidelity sound reproduction in home movie systems.
Innovation Solution
An audio downmix apparatus with dynamic-range control that attenuates the audio source signal by a constant ratio, rectifies it to produce an absolute value, calculates a power gain value, and adjusts the gain to achieve effective gain control without division calculations, thereby simplifying the circuit and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If destructive compression methods (Dolby Digital or DTS) are used for audio encoding, then audio files occupy smaller storage space and can be transmitted by marginal bandwidth, but complex mathematical processes and significant computational resources are required, making the system costly and complex
Solution Approach 1:
The patent extracts only the essential gain control function from the complex encoding system, implementing a separate, simplified gain control mechanism that operates independently from the main compression algorithm. This allows the complex compression to be handled once during encoding, while playback uses a simple, dedicated gain control circuit that requires minimal computational resources.
Solution Approach 2:
The patent performs gain control adjustments in advance during the encoding process, pre-calculating and embedding gain adjustment parameters in the compressed audio data. This preliminary action eliminates the need for complex real-time calculations during playback, as the gain control is already determined and stored with the audio stream.
2Measurement precision
If complex mathematical processes are used for gain control in audio encoding, then accurate gain adjustment can be achieved, but powerful CPU and large memory are required, increasing system cost
Solution Approach 1:
The patent replaces expensive, complex computational resources with a simpler, dedicated gain control circuit designed for a single purpose. This specialized hardware implementation provides accurate gain control without requiring a powerful general-purpose CPU or large memory, effectively trading versatility for efficiency in the gain control function.
Solution Approach 2:
The patent changes the approach from complex real-time mathematical calculations to using pre-calculated gain parameters stored in the compressed audio data. By transforming the problem from computation to retrieval and application of stored parameters, the system achieves accurate gain control with minimal computational overhead.
Data Source
AI summary
A method for audio downmix apparatus with dynamic-range control includes steps as follows. The procedure first calculates the power of a surround audio channel and a central audio channel and then estimates whether a gain of the surround audio channel and the central audio channel saturate or not. When the gain is saturated, the procedure enters a step for adjusting a gain of dynamic range control; while the gain is not saturated, the procedure enters a saturation process. After the step of adjusting a gain of dynamic range control, then processes a gain calculation; and then changes the gain and estimates whether the gain reaches a default value or not. When the gain reaches the default value, then the gain will be outputted. When the gain does not reach the default value, continues to process the gain calculation and change the gain.