Analysis by synthesis spatial audio coding

Abstract

This study presents a novel spatial audio coding (SAC) technique, called analysis by synthesis SAC (AbS-SAC), with a capability of minimising signal distortion introduced during the encoding processes. The reverse one-to-two (R-OTT), a module applied in the MPEG Surround to down-mix two channels as a single channel, is first configured as a closed-loop system. This closed-loop module offers a capability to reduce the quantisation errors of the spatial parameters, leading to an improved quality of the synthesised audio signals. Moreover, a sub-optimal AbS optimisation, based on the closed-loop R-OTT module, is proposed. This algorithm addresses a problem of practicality in implementing an optimal AbS optimisation while it is still capable of improving further the quality of the reconstructed audio signals. In terms of algorithm complexity, the proposed sub-optimal algorithm provides scalability. The results of objective and subjective tests are presented. It is shown that significant improvement of the objective performance, when compared to the conventional open-loop approach, is achieved. On the other hand, subjective test show that the proposed technique achieves higher subjective difference grade scores than the tested advanced audio coding multichannel.

Analisis Kinerja Skema MPEG Surround Pada Pengkodean Audio 22 Kanal Menggunakan Bitrate 1000 - 2000 Kbps

“…Proses downmixing audio multikanal 22.2 dilakukan dengan metode sinyal audio masukan 22 kanal diproses pada block downmix yang berisikan encoding block serta dikonversi jadi satu audio mono dengan spatial parameternya yang berbentuk CLD, ICC dan suatu sinyal residu [15]. Spatial parameter yang diekstrak ini nanti akan berperan sebagai parameter buat merekonstruksi kembali sinyal mono dari hasil proses downmix jadi audio multikanal kembali [20]. Proses downmixing pada audio multikanal 22.2 bisa dilihat pada gambar 1.…”

Reviews on Technology and Standard of Spatial Audio Coding

“…Analysis by Synthesis (AbS) concept [66][67][68][69][70][71], which has been widely applied in many ISSN: 2302 -2949…”

Investigation on objective performance of closed-loop spatial audio coding

“…Based on MPEG Surround, a closed-loop spatial audio coding technique [18], [19] has been proposed and its performance, tested objectively and subjectively, has been reported to show the advantages of the closed-loop system in order to improve the quality of multichannel audio reproduction. However, it is not clear yet how the effect of different spatial parameter quantisers on the performance of the closed-loop codec.…”