N-tuple VLC Decoder Escape Indicator Bit Lookup
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Solution Overview
Problem
Conventional methods for decoding N-tuple variable length codes in audio codecs like AAC and MP3 suffer from poor computing performance due to symbol-by-symbol comparison for escape code detection, which is inefficient and limited to specific media standards.
Innovation Solution
Incorporating an escape indicator bit in Huffman lookup tables to simplify escape code detection, allowing parallelism between symbol decoding and escape condition detection, and enabling flexible handling of escape codes without hard-coding specific standards, allowing for efficient decoding of both existing and future media standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symbol-by-symbol comparison is used for escape code detection, then escape codes can be detected, but computing performance deteriorates due to inefficient processing
Solution Approach 1:
The patent pre-calculates and stores escape code detection information in lookup tables during table generation, rather than performing symbol-by-symbol comparisons during actual decoding. This preliminary preparation allows the decoder to quickly determine escape conditions by simple table lookup, significantly improving computing performance while maintaining detection accuracy.
Solution Approach 2:
The patent creates a copied and optimized version of the escape detection logic in the form of pre-computed lookup tables. Instead of executing the original complex comparison logic during decoding, the system uses a pre-prepared copy of the detection results stored in tables, enabling faster processing without sacrificing detection reliability.
2Productivity
If hard-wired escape handling logic is implemented, then escape codes can be handled efficiently, but adaptability to different media standards deteriorates
Solution Approach 1:
The patent makes the escape handling system dynamic by allowing the lookup tables to be configured for different media standards. The escape threshold values and detection logic in the tables can be adjusted according to the specific standard being used (e.g., AAC, MP3), enabling the same decoder hardware to efficiently handle multiple standards without hard-wiring to a single standard.
Solution Approach 2:
The patent designs a universal escape handling mechanism that can work with multiple media standards through configurable lookup tables. The same decoder structure and escape detection logic can serve different standards by simply changing the table contents, making the system multi-functional and adaptable rather than dedicated to a single standard.
3Ease of operation
If lookup tables include escape indicator bits, then escape detection is simplified, but device complexity increases due to larger table size
Solution Approach 1:
The patent segments the lookup table into multiple fields, including a dedicated escape indicator bit field. This segmentation allows the escape detection function to be separated from the main decoding logic, with the indicator bits providing a simple yes/no signal about escape conditions. The segmentation makes the table more manageable and the detection process simpler despite the increased size.
Solution Approach 2:
The escape indicator bits act as an intermediary between the decoded symbol values and the escape handling logic. Rather than requiring complex comparison operations, the indicator bits provide a intermediate signal that directly indicates whether escape handling is needed, simplifying the overall detection process while the table size increase is accepted as a trade-off for this operational simplicity.
Data Source
AI summary
This application provides a flexible and efficient way to handle escape symbols during decoding of N-tuple variable length codes (VLCs). The user can request that the decoder resolve a sequence of symbols. The Huffman lookup tables can contain a field to notify the decoder if a given N-tuple VLC includes an escape symbol. For non-escape symbols, as identified by the escape indicator bit in the Huffman lookup table entry, the decoder can finish resolving the N symbols of the N-tuple without requiring a symbol-by-symbol comparison of each symbol to detect escape conditions. For escape symbols, as identified by the escape indicator bit in the Huffman lookup table entry, the decoder can either look back to the user for help, or use pre-defined logic to resolve the escape symbols. Aspects of certain embodiments enable parallelism between Huffman symbol decoding and escape condition detection without losing future expandability.