COP Packetizing Circuit for Variable Bit Rate Audio Power Reduction
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Solution Overview
Problem
Conventional interfaces used in mobile computing devices, such as SLIMBus or those defined by the International Electrotechnical Commission (IEC) 61937 standard, primarily support transmission of pulse code modulation (PCM) data at a constant bit rate, making it difficult to transmit audio formats with varying bit rates, like Bluetooth™, aptX, and AAC, without power inefficiencies.
Innovation Solution
The development of a COP packetizing circuit that generates compressed-over-pulse code modulation (COP) packets with a packet length proportional to the PCM frame length, allowing for transmission over isochronous PCM interfaces with reduced power consumption by scaling bit rates, and supporting multiple audio formats through a single packetizing scheme.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional PCM interfaces transmit encoded audio frames at constant bit rate, then interface compatibility is maintained, but power consumption increases and support for variable bit rate audio formats is lost
Solution Approach 1:
The patent changes the bit rate parameter from constant to variable by scaling it according to the ratio of encoded audio frame size to PCM frame size. This allows the system to adapt to different audio formats (SBC, aptX, AAC) with varying compression ratios, reducing power consumption when lower bit rates suffice while maintaining compatibility with PCM interfaces through the COP packetization framework
Solution Approach 2:
The COP packetizing circuit provides a universal interface that handles multiple audio formats (SBC, aptX, aptX-HD, AAC) through a single packetization scheme. The circuit universally applies the bit rate scaling formula across all formats, enabling one interface to serve multiple functions while maintaining PCM interface compatibility
2Use of energy by moving object
If encoded audio frames are transmitted with variable bit rates, then power consumption is reduced, but compatibility with conventional PCM interfaces is compromised
Solution Approach 1:
The COP packetizing circuit acts as an intermediary between variable bit rate encoded audio frames and constant bit rate PCM interfaces. It mediates the transmission by packetizing encoded frames into COP packets with standardized structure (header + subframe + zero padding), enabling variable bit rate audio to traverse conventional PCM interfaces without compromising compatibility while still achieving power savings
Solution Approach 2:
The patent transforms the variable bit rate parameter into a compatible form for PCM interfaces by scaling it according to the compression ratio. The bit rate is dynamically adjusted based on the encoded frame size relative to the PCM frame size, maintaining interface compatibility while exploiting compression efficiency to reduce power consumption
3Device complexity
If a single packetizing scheme is used for multiple audio formats, then device complexity is reduced, but precision in handling format-specific requirements may be compromised
Solution Approach 1:
The patent implements a universal packetizing scheme that handles multiple audio formats (SBC, aptX, aptX-HD, AAC) through a single unified approach. The COP packet structure (header with format identifier + subframe with encoded data + zero padding) universally accommodates all formats without requiring format-specific packetization logic, reducing device complexity while maintaining sufficient precision through the standardized framework
Data Source
AI summary
Aspects disclosed in the detailed description include packetizing encoded audio frames into compressed-over-pulse code modulation (PCM) (COP) packets for transmission over PCM interfaces. In one aspect, a COP packetizing circuit is configured to receive an encoded audio frame generated from a PCM frame, and generate a COP packet that includes the encoded audio frame irrespective of the audio format. The COP packet is generated with a packet length proportional to a PCM length of the PCM frame, allowing the COP packetizing circuit to transmit the COP packet over an isochronous PCM interface with a lower bit rate than the PCM frame to reduce power. The COP packetizing circuit provides a mobile computing device with a single packetizing scheme that supports multiple audio formats, and allows for reducing power through bit rate scaling.