Band Extension Decoding Apparatus for Audio-Video Synchronization
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Solution Overview
Problem
Conventional band extension techniques in audio decoding cause delays and resource increases, particularly when synchronizing audio with video, as they require additional processing time and memory, making it difficult to maintain optimal timing and efficiency.
Innovation Solution
A decoding apparatus and method that includes an obtaining unit for encoding results, a generating unit to create a spectrum using normalized lower and higher frequency envelopes, a randomizing unit to randomize the phase based on the degree of concentration, and a combining unit to denormalize the spectrum, allowing for simultaneous decoding and band extension without additional delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional band extension technique is used, then higher frequency spectrum can be generated, but delay time increases and resources are consumed
Solution Approach 1:
The patent applies preliminary action by performing band extension in advance during the encoding process rather than during decoding. The higher frequency envelope is extracted and prepared beforehand, allowing the decoding process to simply replicate and combine the spectrum without requiring additional processing time during playback, thus eliminating delay while maintaining quality improvement.
Solution Approach 2:
The patent segments the frequency spectrum into lower frequency components (which are fully encoded) and higher frequency components (where only the envelope is encoded). This segmentation allows the decoding apparatus to efficiently reconstruct the full spectrum by combining the lower frequency spectrum with synthesized higher frequency components based on the envelope information, reducing processing requirements and eliminating delay.
2Reliability
If band extension processing is added to decoding apparatus, then higher frequency spectrum can be generated, but device complexity and resources increase
Solution Approach 1:
The patent extracts only the essential envelope information from the higher frequency spectrum during encoding, discarding the full high-frequency spectrum data. This extraction allows the decoding apparatus to reconstruct the higher frequency spectrum using simple replication and envelope modulation techniques, significantly reducing the computational resources and complexity required compared to traditional full-spectrum processing.
Solution Approach 2:
The patent makes the envelope extraction and processing mechanism universal by using the same envelope-based approach for both encoding and decoding operations. The decoding apparatus leverages the encoded envelope information to perform band extension functionality, making the system more efficient and reducing the need for separate dedicated high-frequency processing hardware.
Data Source
AI summary
The present invention relates to a decoding apparatus, a decoding method, an encoding apparatus, an encoding method, and programs that can shorten the delay time caused by the band extension at the time of decoding, and restrain increases in resources on the decoding side.A higher frequency component generating unit (73) generates a pseudo higher frequency spectrum by using a lower frequency spectrum (SP-L) and a higher frequency envelope (ENV-H). A phase randomizing unit (74) randomizes the phase of the pseudo higher frequency spectrum, based on a random flag (RND). An inverse MDCT unit (75) denormalizes the lower frequency spectrum (SP-L) by using a lower frequency envelope (ENV-L), and combines the pseudo higher frequency spectrum supplied from the phase randomizing unit (74) with the denormalized lower frequency spectrum (SP-L). The combination result is used as the spectrum of the entire band. The present invention can be applied to a decoding apparatus that performs band extension decoding, for example.