Investigation on objective performance of closed-loop spatial audio coding

Closed-loop spatial audio coding is a compression technique, developed based on MPEG Surround (MPS) standard, having an advantage of minimising distortion due to quantisation process of spatial parameters. Despite the MPS is developed based on filterbank, however, this closed-loop system performs better on Modified Discrete Cosine Transform (MDCT). Considering its high performance over the open-loop system, this paper presents further investigation on objective performance of closed-loop spatial audio coding against various quantisers of spatial parameters. Experiments have been conducted to measure signal to noise ratio (SNR) across different types of uniform spatial quantisers at various operating bitrates. The results show that the SNR achieved by the open-loop approach is strongly affected by the type of the quantiser while, in contrast, the SNR achieved by the closed-loop approach is relatively constant regardless the number of bits used in the quantisers. Moreover, the results also show that the closed-loop configuration can consistently improve SNR in any quantisation scheme.