Audio Bus Power Conservation via Differential PCM Encoding
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Solution Overview
Problem
Current audio bus technologies, such as SLIMBUS and SOUNDWIRE, consume excessive power due to the high number of transitions in non-return to zero inverted (NRZI) encoding, as approximately 50% of the signal is ones, leading to increased power consumption.
Innovation Solution
The method involves comparing the number of ones in the current PCM audio sample to the immediately preceding sample and sending either the difference or the current sample, whichever has fewer ones, to reduce the number of transitions over the NRZI audio bus, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If NRZI encoding is used for audio data transmission, then data can be transmitted over the audio bus, but the number of transitions increases leading to excessive power consumption
Solution Approach 1:
The patent changes the encoding parameter from standard NRZI to a modified NRZI encoding where consecutive identical values are run-length encoded. This parameter change reduces the number of transitions in the transmitted signal, directly addressing the power consumption issue while maintaining data transmission functionality.
Solution Approach 2:
The patent creates a modified copy of the NRZI encoding scheme by introducing run-length encoding for consecutive identical values. This copied and adapted encoding method preserves the essential functionality of NRZI while reducing transition density, thereby lowering power consumption without requiring a complete change to the transmission protocol.
2Loss of information
If standard NRZI encoding transmits all audio samples, then complete audio data is transmitted, but the number of ones in the signal causes excessive transitions and power consumption
Solution Approach 1:
The patent extracts and transmits only the differential values between consecutive audio samples rather than transmitting all original sample values. By taking out only the necessary difference information and applying run-length encoding to consecutive zeros, the patent reduces transmission data volume and transition count while preserving the ability to reconstruct complete audio data at the receiver.
3Quantity of substance
If differential encoding is used to reduce data size, then fewer bits are transmitted, but the number of ones in the difference values may still cause transitions
Solution Approach 1:
The patent applies run-length encoding specifically to sequences of consecutive zero differences, treating them as periodic or repeated patterns. By detecting and encoding runs of identical values (particularly zeros) rather than transmitting each individual difference value, the patent significantly reduces the number of transitions while maintaining accurate reconstruction of the original audio signal.
Data Source
AI summary
A number of ones in the difference between a current pulse code modulated (PCM) audio sample and an immediately preceding audio sample is compared to a number of ones in the current audio sample to determine which has the fewer number of ones. The audio source sends either the difference or the current audio sample, whichever has fewer ones. By reducing the number of ones sent over a non-return to zero inverted (NRZI) audio bus from an audio source to an audio sink, the number of transitions is reduced, which reduces the power consumed relative to a transmission that does not use this process.