Seamless Compressed Audio Stream Switching
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Solution Overview
Problem
Current audio compression technologies, such as MPEG and AC-3, do not allow for seamless concatenation or switching of compressed audio fragments due to their frame-based encoding, leading to data loss or padding issues and audible artifacts when transitioning between fragments.
Innovation Solution
The method involves aligning audio fragments to frame boundaries and prepending an additional frame to set the encoder's history, which is then discarded, ensuring seamless playback by maintaining consistent encoder and decoder states across transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If audio fragments are compressed using frame-based encoding (MPEG/AC-3), then compression efficiency is improved, but seamless concatenation becomes impossible due to frame boundary constraints
Solution Approach 1:
The patent applies preliminary action by pre-padding audio fragments with silence data before compression. This ensures that each fragment's duration is extended to a multiple of the frame size, allowing seamless concatenation without frame boundary issues. The padding is performed in advance during content creation, eliminating the need for complex frame-synchronization mechanisms during playback.
2Productivity
If frame-based compression is used, then data transmission efficiency is improved, but data loss or padding artifacts occur at frame boundaries
Solution Approach 1:
The patent implements beforehand cushioning by inserting silence periods (padding) at the beginning or end of audio fragments. This cushioning ensures that when fragments are concatenated, the transition occurs at frame boundaries without causing data loss or audible artifacts. The silence padding acts as a buffer that absorbs the frame boundary discontinuities.
3Device complexity
If audio fragments are encoded independently, then encoding complexity is reduced, but encoder state inconsistency causes playback artifacts
Solution Approach 1:
The patent changes the parameter of fragment duration to be a multiple of frame size. This simple parameter change ensures that independently encoded fragments will align properly at frame boundaries during concatenation, maintaining encoder-decoder state consistency without requiring complex inter-fragment synchronization mechanisms.
4Reliability
If frame boundaries are enforced for compression, then compression reliability is improved, but audio content must be truncated or padded
Solution Approach 1:
The patent performs preliminary padding of audio fragments with silence data to extend their duration to the nearest multiple of frame size. This preliminary action preserves the complete original audio content while adding minimal silent periods, rather than truncating content to fit frame boundaries. The padding is performed during content creation, making it invisible during playback.
Data Source
AI summary
A system and method for seamless switching and concatenation of compressed audio streams in Internet, Digital Radio, Digital Television, DVD, storage, and other applications. The technology allows switching between streams at pre-determined points without the introduction of audible artifacts. It can be used for the personalization messages such as advertisements, news systems and other.