VR Audio Latency Reduction via Client-Side HRTF Convolution

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Solution Overview

Problem

Current virtual reality (VR) systems face challenges in providing low audio latency, which disrupts the immersive experience due to high computational demands in recalculating audio frames based on user head position changes, leading to latency issues and inaccurate positional audio cues.

Innovation Solution

The implementation of a mechanism that uses head-related transfer functions (HRTFs) to modify existing audio frames in real-time on a client device, reducing computational overhead and latency by applying HRTFs to audio frames generated based on prior positions, allowing for quick adaptation to new head positions without relying on intensive server computations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If audio frames are recalculated in real-time based on user head position changes, then positional audio accuracy is improved, but audio latency increases due to intensive computation

Engineering Contradiction:
Improvepositional audio accuracyVSAvoidaudio latency
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system pre-calculates and stores head-related transfer functions (HRTFs) for various head positions before they are needed. When the user moves their head, the system retrieves and applies the pre-computed HRTF corresponding to the new position, avoiding real-time computation delays while maintaining accurate positional audio cues.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically selects from a set of pre-computed HRTFs based on the user's current head position. Instead of static audio rendering, the system continuously adapts by choosing the most appropriate pre-calculated HRTF that matches the user's head orientation and position, enabling real-time adaptation without intensive computation.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If intensive real-time computation is performed to generate accurate positional audio cues, then audio quality is improved, but system complexity and processing requirements increase

Engineering Contradiction:
Improvepositional audio cue accuracyVSAvoidcomputational requirements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Complex HRTF calculations are performed in advance and stored in lookup tables. The runtime system only needs to perform simple retrieval and application operations, dramatically reducing computational requirements while maintaining high positional audio accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of computing unique audio renderings for each possible head position, the system creates a library of pre-computed audio responses (copies) for representative positions. These copies are then selected and applied based on the user's actual head position, reducing computational complexity while preserving audio fidelity.

Inventive Principle:
Principle #26Copying

3Productivity

If audio frames are generated based on prior head positions, then computational overhead is reduced, but audio latency increases

Engineering Contradiction:
Improveaudio frame generation speedVSAvoidaudio latency
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system pre-computes audio frames for multiple potential head positions in advance. When the user moves their head, the system has already prepared the corresponding audio frames, allowing immediate application without computation delays while maintaining synchronization with the user's actual position.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS10871939B2Method and system for immersive virtual reality (VR) streaming with reduced audio latency
Publication Date: 2020.12.22 NVIDIA CORP
  • US10871939B2 patent drawing
  • US10871939B2 patent drawing
  • US10871939B2 patent drawing

AI summary

A virtual reality (VR) audio rendering system and method of using HRTF functions to quickly capture new positional cues to pre-computed audio frames responsive to changes in user position relative to sound systems. In a client-server VR system, when a user position change is detected, the client determines an appropriate HRTF based on the new position and convolves them with a set of audio frames that have been generated by the server based on a prior position, resulting in modified frames for rendering. Meanwhile, the client propagates the new position to the server to generate subsequent audio frames for the corrected position. As HRTF convolution is computationally inexpensive, the latency between user position change and the resultant sound change as perceived by the user can be significantly reduced. As a result, an immersive VR experience of the user can be preserved.