Surround Sound Processed by Opus Codec: A Perceptual Quality Assessment


The article describes the first perceptual quality study of 5.1 surround sound that has been processed by the Opus codec standardised by the Internet Engineering Task Force (IETF). All listening sessions with up to five subjects took place in a slightly sound absorbing laboratory – simulating living room conditions. For the assessment we conducted a Degradation Category Rating (DCR) listeningopinion test according to ITU-T P.800 recommendation with stimuli for six channels at total bitrates between 96 kbit/s and 192 kbit/s as well as hidden references. A group of 27 naive listeners compared a total of 20 sound samples. The differences between uncompressed and degraded sound samples were rated on a five-point degradation category scale resulting in Degradation Mean Opinion Score (DMOS). The overall results show that the average quality correlates with the bitrates. The quality diverges for the individual test stimuli depending on the music characteristics. Under most circumstances, a bitrate of 128 kbit/s is sufficient to achieve acceptable quality.

Year: 2017
In session: Poster
Pages: 300 to 307