Subjective Evaluation of Music Compressed with the ACER Codec Compared to AAC, MP3, and Uncompressed PCM

Cunningham, Stuart; McGregor, Iain

Abstract

Audio data compression has revolutionised the way in which the music industry and musicians sell and distribute their products. Our previous research presented a novel codec named ACER (Audio Compression Exploiting Repetition), which achieves data reduction by exploiting irrelevancy and redundancy in musical structure whilst generally maintaining acceptable levels of noise and distortion in objective evaluations. However, previous work did not evaluate ACER using subjective listening tests, leaving a gap to demonstrate its applicability under human audio perception tests. In this paper, we present a double-blind listening test that was conducted with a range of listeners (N=100). The aim was to determine the efficacy of the ACER codec, in terms of perceptible noise and spatial distortion artefacts, against de facto standards for audio data compression and an uncompressed reference. Results show that participants reported no perceived differences between the uncompressed, MP3, AAC, ACER high quality, and ACER medium quality compressed audio in terms of noise and distortions but that the ACER low quality format was perceived as being of lower quality. However, in terms of participants’ perceptions of the stereo field, all formats under test performed as well as each other, with no statistically significant differences. A qualitative, thematic analysis of listeners’ feedback revealed that the noise artefacts that produced the ACER technique are different from those of comparator codecs, reflecting its novel approach. Results show that the quality of contemporary audio compression systems has reached a stage where their performance is perceived to be as good as uncompressed audio. The ACER format is able to compete as an alternative, with results showing a preference for the ACER medium quality versions over WAV, MP3, and AAC. The ACER process itself is viable on its own or in conjunction with techniques such as MP3 and AAC.

Citation

Cunningham, S., & McGregor, I. (2019). Subjective Evaluation of Music Compressed with the ACER Codec Compared to AAC, MP3, and Uncompressed PCM. International Journal of Digital Multimedia Broadcasting, 2019, 1-16. https://doi.org/10.1155/2019/8265301

• Journal Article Type: Article
• Acceptance Date: Jun 17, 2019
• Online Publication Date: Jul 11, 2019
• Publication Date: Jul 11, 2019
• Deposit Date: Jul 13, 2019
• Publicly Available Date: Jul 15, 2019
• Journal: International Journal of Digital Multimedia Broadcasting
• Print ISSN: 1687-7578
• Electronic ISSN: 1687-7586
• Publisher: Hindawi
• Peer Reviewed: Peer Reviewed
• Volume: 2019
• Pages: 1-16
• DOI: https://doi.org/10.1155/2019/8265301
• Keywords: Media Technology; Electrical and Electronic Engineering; Communication
• Public URL: http://researchrepository.napier.ac.uk/Output/1959453
• Contract Date: Jul 15, 2019