Han-gil Moon

A multi-channel audio compression method with virtual source location information for MPEG-4 SAC

Binaural cue coding (BCC) was introduced as an efficient representation method for MPEG-4 SAC (spatial audio coding). However, in a low bit-rate environment, the spectrum of BCC output signals degrades with respect to the perceptual level. The proposed system in this paper estimates VSLI (virtual source location information) as the side information. The VSLI is the angle representation of spatial images between channels on playback layout. The subjective assessment results show that the proposed method provides better audio quality than the BCC method for encoding multi-channel signals.

Backward-compatible terrestrial digital multimedia broadcasting system for multichannel audio service

In this paper, a Terrestrial Digital Multimedia Broadcasting (T-DMB) system for a multichannel audio service is proposed. The multichannel audio information on the T-DMB system proposed in this paper consists of a stereo audio signal coded by BSAC and additional multichannel side information coded by MPEG surround. These two types of information are conveyed through two elementary streams (ES), respectively. To control two elementary streams, two object descriptor (OD) streams are exploited, each of which transmits OD commands, including ObjectDescriptorUpdate and ES_DescriptorUpdate, related to a stereo audio signal and additional multichannel side information, respectively. With this method, the proposed system can convey multichannel side information while guaranteeing backward compatibility for the legacy T-DMB terminals, and moreover makes it possible to provide various advanced service scenarios with outstanding extensibility.

Low latency audio coder design for bluetooth and bluetooth low energy

Wireless audio service attracts increasing attention both in mobile and in home audio market. For high quality audio service especially on wireless network, the audio codec with low latency is indispensable since the latency prevents a user from being immersed in the service. This paper presents a low latency audio coder design with a short length window. Side effects due to the short length window are mitigated by the proposed coding tools such as pitch coding and low frequency masking threshold control. The audio quality assessed by the objective and subjective manners shows that the proposed design outperforms the well-known commercial codec.

A multi-channel audio compression method with virtual source location information

Binaural cue coding (BCC) was introduced as an efficient representation method for MPEG-4 SAC (Spatial Audio Coding). However, in a low bit-rate environment, the spectrum of BCC output signals degrades with respect to the perceptual level. The proposed system in this paper estimates VSLI (virtual source location information) as the side information. The VSLI is the angle representation of spatial images between channels on playback layout. The subjective assessment results show that the proposed method provides better audio quality than the BCC method for encoding multi-channel signals.

Multi-microphone approach for reliable acoustic data transmission

Acoustic data transmission (ADT) is a branch of the audio data hiding techniques enabling data communication in short-range aerial space between a loudspeaker and a microphone. In this paper, we extend ADT method to a multichannel approach utilizing multiple microphones in order to enhance transmission reliability while ensuring compatibility with the previous single-microphone receiver. In the proposed multichannel method, the data coefficients obtained from each channel are linearly combined with weighting factors determined based on the Wiener-type channel estimation. From the experimental results, the proposed multichannel method has been shown to be effective in reducing bit errors in reverberant environments.

Sound customizing system for high-quality TV sound based on hearing threshold measurement

This paper presents the sound customizing system, which compensates the perceptual sound quality drop caused by individual hearing loss and poor room acoustic environment. In order to compensate the quality drop, the overall perceptual hearing profile is measured and the proposed algorithm customizes the sound according to the personal profile. The subjective assessment result shows that the proposed method improves the overall sound quality.

Low latency audio coder design for high quality audio service on server-client environment

Low latency audio coding attracts increasing attention among high quality communication applications such as video conferencing system and server-client media applications such as cloud computing based interactive A/V service. This paper presents a low latency audio coding scheme which can achieve both low delay and high subjective audio quality at the same time. In order to guarantee low delay, the proposed coding system incorporates low overlap window while preserving the window size as same as that of conventional (AAC) long window. The supplementary signal processing tool is incorporated to enhance the audio quality. The proposed coding scheme achieves the delay of 24ms in 48 kHz and the MUSHRA score which is comparable to that of commercialized AAC.