Dynamic Jitter Buffer Play-out Delay Control
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Solution Overview
Problem
Existing methods for compensating for delay jitter in data packets transmitted over packet-switched networks often result in excessive play-out delays, leading to quality degradation in speech data transmission, especially in IP telephony, due to the inability to adaptively adjust to varying network conditions effectively.
Innovation Solution
A method that integrates differences in delay between data packets to determine an optimal play-out delay, using minimum and maximum value detectors to adjust the play-out delay dynamically, ensuring it remains as short as possible while preventing buffer underflow, by setting the play-out delay as a function of the difference between maximum and minimum detected values, with optional multiplicative or additive safety factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed play-out delay is used in the jitter buffer, then data packets are prevented from being discarded due to late arrival, but the speech data quality degrades due to excessive delay
Solution Approach 1:
The patent implements a dynamic play-out delay mechanism where the delay value is continuously adjusted based on the measured delay jitter of incoming data packets. The play-out delay is set as a function of the measured jitter, allowing the system to adapt to varying network conditions rather than using a fixed delay value. This resolves the contradiction by making the delay responsive to actual network状况, preventing buffer underflow when jitter is high while minimizing delay when jitter is low.
Solution Approach 2:
The system employs feedback by measuring the delay jitter of incoming data packets and using this measurement to adjust the play-out delay. The delay compensation value is calculated based on the measured jitter, creating a closed-loop control system. This feedback mechanism allows the jitter buffer to automatically adapt to changing network conditions, resolving the contradiction between reliability and time loss by using real-time information to optimize the delay parameter.
2Loss of time
If the play-out delay is reduced to improve speech quality, then buffer underflow occurs when data packets arrive later than expected
Solution Approach 1:
The patent makes the play-out delay dynamic by adjusting it according to the measured delay jitter. When jitter is high, the play-out delay increases to prevent buffer underflow; when jitter is low, the delay decreases to improve speech quality. This dynamic adjustment resolves the contradiction by making the delay adaptive to actual network conditions rather than fixed.
Solution Approach 2:
The system changes the play-out delay parameter based on the measured jitter characteristics. The delay is set as a function of the measured jitter, allowing the parameter to vary within a range that balances speech quality and buffer underflow prevention. This parameter change approach resolves the contradiction by optimizing the delay value according to actual network状况.
3Reliability
If a large play-out delay is used to prevent buffer underflow, then speech data quality degrades due to excessive delay
Solution Approach 1:
The patent implements dynamic adjustment of the play-out delay based on measured jitter, allowing the system to use large delays only when necessary (high jitter) and small delays when possible (low jitter). This resolves the contradiction by making the delay responsive to actual network conditions rather than consistently large.
Solution Approach 2:
The system uses feedback from jitter measurements to adjust the play-out delay appropriately. When jitter measurements indicate stable network conditions, the delay is reduced to improve quality; when jitter increases, the delay is increased to prevent underflow. This feedback-driven approach resolves the contradiction between reliability and productivity.
4Loss of time
If the play-out delay is dynamically adjusted to minimize delay, then buffer underflow may occur during high jitter periods
Solution Approach 1:
The patent changes the play-out delay parameter as a function of measured jitter, allowing the delay to vary within an optimal range. The delay is set based on the measured jitter characteristics, balancing the need to minimize delay with the need to prevent buffer underflow during high jitter periods.
Solution Approach 2:
The system applies a safety margin or cushion to the calculated play-out delay to account for unpredictable jitter variations. This beforehand cushioning ensures that even during high jitter periods, the delay is sufficient to prevent buffer underflow while still being minimized as much as possible given the uncertainty.
Data Source
AI summary
To compensate for jitter in the delay of data packets (1) which are transmitted over a transmission link (40), e.g. a data network, the data packets (1) are buffer-stored in a jitter buffer (10) and are then played out of the jitter buffer (10) at preset intervals of time, after an additional play-out delay (ΔT). The additional play-out delay (ΔT) is set in this case as a function of a magnitude that is determined of the delay jitter, for which purpose differences in delay between successive data packets (1) are determined and an integrated value of the differences in delay is formed by integration. The additional play-out delay (ΔT) is then set on the basis of the integrated value of the differences in delay.