PVQ Indexing With Leading-Sign Extraction for 32-Bit DSPs
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Solution Overview
Problem
Existing pyramid vector quantization (PVQ) indexing schemes are limited by 32-bit integer ranges and cannot be efficiently implemented in digital signal processor (DSP) architectures that only support signed 32-bit integers, leading to increased complexity and overhead in indexing and de-indexing operations.
Innovation Solution
The proposed method involves extracting a leading sign from the input vector and using it to index the vector with a pyramid vector quantization enumeration scheme, reducing the dynamic range requirements and enabling the use of 33-bit PVQ indices in 32-bit DSP hardware, while also supporting signed arithmetic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing PVQ indexing schemes are used, then indexing can be performed, but the implementation is limited to 32-bit integer ranges and cannot be efficiently implemented in DSP architectures that only support signed 32-bit integers
Solution Approach 1:
The patent segments the 33-bit PVQ index into two parts: a sign bit and a 32-bit magnitude. This segmentation allows the index to be processed using signed 32-bit integer arithmetic in DSP architectures, resolving the contradiction between adaptability to DSP hardware and indexing capability.
Solution Approach 2:
The patent changes the parameter representation by introducing a sign bit and using two's complement notation for the magnitude. This parameter transformation enables the PVQ indexing scheme to work within the constraints of signed 32-bit integer DSP architectures while maintaining 33-bit indexing capability.
2Measurement precision
If 33-bit PVQ indices are used, then more precise indexing is achieved, but the dynamic range requirements increase making implementation in 32-bit DSP hardware difficult
Solution Approach 1:
The 33-bit index is segmented into a sign bit and a 32-bit magnitude, allowing precise indexing to be achieved while fitting within 32-bit DSP hardware constraints through signed integer representation.
Solution Approach 2:
The patent introduces a sign dimension to the indexing system, transforming the representation from unsigned 33-bit integers to signed 32-bit integers with an explicit sign bit, thereby achieving the same precision within hardware constraints.
3Ease of operation
If large table lookup is used for de-indexing, then decomposition is made low complex, but huge stored ROM tables are required
Solution Approach 1:
The patent extracts the sign information from the PVQ index and processes it separately from the magnitude. This extraction allows the de-indexing operation to use smaller lookup tables for the magnitude while handling the sign through separate logical operations, reducing memory requirements.
Solution Approach 2:
By segmenting the index into sign and magnitude components, the patent enables independent processing of each part during de-indexing, allowing the use of smaller, more manageable lookup tables rather than requiring huge tables for the entire 33-bit index.
Data Source
AI summary
A method for pyramid vector quantization indexing of audio/video signals comprises obtaining of an integer input vector representing the audio/video signal samples. A leading sign is extracted from the integer input vector. The leading sign is a sign of a terminal non-zero coefficient in the integer input vector. The terminal non-zero coefficient is one of a first non-zero coefficient and a last non-zero coefficient in the integer input vector. The integer input vector is indexed with a pyramid vector quantization enumeration scheme into an output index representing the audio/video signal samples. The pyramid vector quantization enumeration scheme is designed for neglecting the sign of the terminal non-zero coefficient. The output index and the leading sign are outputted. A corresponding method for de-indexing, an encoder, a decoder, and computer programs therefore are also disclosed.