Adaptive FEC Audio Encoding for Bandwidth and Delay Reduction
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Solution Overview
Problem
Existing forward error correction (FEC) systems in packet-switched networks often result in increased bandwidth consumption and delay, leading to unnecessary waste and degraded performance due to the generation of redundant payloads with lower quality audio signals, especially in media-dependent FEC.
Innovation Solution
An adaptive method for encoding audio streams that divides the audio into frames, determines frequency bands and power envelopes, and encodes these as low-bitrate redundant transmission frames, incorporating noise generation based on the data in the frames to improve FEC efficiency and reduce bandwidth and delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FEC redundant payloads are generated to combat packet loss, then voice quality is improved, but bandwidth consumption increases
Solution Approach 1:
The patent applies local quality by generating FEC redundant payloads only for specific frequency bands where packet loss is detected, rather than encoding all frequency bands. The system identifies affected frequency bands and creates repair payloads selectively for those bands, reducing overall bandwidth consumption while maintaining voice quality in the impacted regions.
Solution Approach 2:
The patent segments the audio spectrum into multiple frequency bands and processes each band independently for FEC. By dividing the audio signal into sub-bands and applying FEC selectively to affected bands rather than treating the entire spectrum uniformly, the system reduces redundant payload generation and optimizes bandwidth usage.
2Reliability
If FEC redundant payloads are generated to combat packet loss, then voice quality is improved, but delay increases
Solution Approach 1:
The patent performs preliminary action by pre-processing audio signals into frequency bands and preparing band-specific data structures before transmission. This preprocessing allows the receiver to quickly identify and repair only the affected frequency bands without waiting for complete packet loss detection, reducing the delay introduced by FEC operations.
Solution Approach 2:
The patent implements dynamics by adaptively adjusting the FEC process based on real-time network conditions and packet loss patterns. The system dynamically selects which frequency bands require FEC repair and adjusts the redundancy generation accordingly, rather than applying static FEC to all bands, thereby minimizing delay while maintaining quality.
3Quantity of substance
If LBR codec is used to generate redundant payload, then bandwidth consumption is reduced, but audio quality of recovered signal deteriorates
Solution Approach 1:
The patent applies parameter changes by transforming the audio signal from the time domain to the frequency domain using MDCT, and then processing different frequency bands with appropriate parameters. By changing the representation parameters of the audio signal and applying FEC selectively to affected bands rather than using a generic LBR codec on the entire signal, the system achieves lower bandwidth consumption without significant quality loss.
Data Source
AI summary
A method of encoding audio information for forward error correction reconstruction of a transmitted audio stream over a lossy packet switched network, the method including the steps of: (a) dividing the audio stream into audio frames; (b) determining a series of corresponding audio frequency bands for the audio frames; (c) determining a series of power envelopes for the frequency bands; (d) encoding the envelopes as a low bit rate version of the audio frame in a redundant transmission frame.