AMBIQUAL - a full reference objective quality metric for ambisonic spatial audio

By Miroslaw Narbutt, Andrew Allen, Jan Skoglund, Michael Chinen, Andrew Hines. 2018

24 citations recorded by the source corpus.

Streaming spatial audio over networks requires efficient encoding techniques that compress the raw audio content without compromising quality of experience. Streaming service providers such as YouTube need a perceptually relevant objective audio quality metric to monitor users' perceived quality and spatial localization accuracy. In this paper we introduce a full reference objective spatial audio quality metric, AMBIQUAL, which assesses both Listening Quality and Localization Accuracy. In our solution both metrics are derived directly from the B-format Ambisonic audio. The metric extends and adapts the algorithm used in ViSQOLAudio, a full reference objective metric designed for assessing speech and audio quality. In particular, Listening Quality is derived from the omnidirectional channel and Localization Accuracy is derived from a weighted sum of similarity from B-format directional channels. This paper evaluates whether the proposed AMBIQUAL objective spatial audio quality metric can predict two factors: Listening Quality and Localization Accuracy by comparing its predictions with results from MUSHRA subjective listening tests. In particular, we evaluated the Listening Quality and Localization Accuracy of First and Third-Order Ambisonic audio compressed with the OPUS 1.2 codec at various bitrates (i.e. 32, 128 and 256, 512kbps respectively). The sample set for the tests comprised both recorded and synthetic audio clips with a wide range of time-frequency characteristics. To evaluate Localization Accuracy of compressed audio a number of fixed and dynamic (moving vertically and horizontally) source positions were selected for the test samples. Results showed a strong correlation (PCC=0.919; Spearman=0.882 regarding Listening Quality and PCC=0.854; Spearman=0.842 regarding Localization Accuracy) between objective quality scores derived from the B-format Ambisonic audio using AMBIQUAL and subjective scores obtained during listening MUSHRA tests. AMBIQUAL displays very promising quality assessment predictions for spatial audio. Future work will optimise the algorithm to generalise and validate it for any Higher Order Ambisonic formats.

Subfields: Cognitive Neuroscience, Computational Mechanics, Signal Processing

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Citations in the corpus

ViSQOL v3: An Open Source Production Ready Objective Speech and Audio Metric (2020, methodology): “ed to collectively as ViSQOL below), are freely available alternatives for speech and audio. These metrics are continually being expanded to cover additional domains. For example the work on AMBIQUAL [9] extends the same principles used in ViSQOLAudio into the ambisonics domain. Advancements in spee”
Jitter Buffer Compensation in Voice over IP Quality Estimation (2019, background): “adding support for Wideband speech [5], [6], audio quality [7] and spatial audio [8]) but did not address the problem of signal mis-alignment caused by jitter buffers.”