Kwangki Kim

Variable Subband Analysis for High Quality Spatial Audio Object Coding

Spatial Audio Object Coding (SAOC) handles a number of audio objects to provide a user with active audio services. It represents all objects as a stereo downmixed signal with some side information, and the bitrate can be significantly reduced compared to that of the conventional audio coders. In spite of the advantage of bitrate reduction, the SAOC has the severe problem such as the degradation of sound quality. To solve the problem while minimizing increase of the bitrate, variable subband analysis and the revised SAOC structure called two-step structure were proposed in this paper. Through a subjective listening test, it was confirmed that the proposed method improves sound quality by a small bitrate increase.

Spatial Audio Object Coding With Two-Step Coding Structure for Interactive Audio Service

An interactive audio service is a new conceptual audio service that provides the users with opportunities for a variety of experiences on the alternative and advanced audio services. In the interactive audio service, users can freely control various audio objects to make their own audio sounds. A spatial audio object coding (SAOC) is a useful technology that can support most parts of the interactive audio service with a relatively low bit-rate, but is very poor to perfect gain control of a certain audio object, i.e., the target audio object. In this paper, the SAOC with a two-step coding structure is proposed to efficiently handle the target audio object as well as the normal audio objects. A transform coded excitation (TCX) based residual coding scheme is presented in the context of the sound quality enhancement. From experimental results, it can be noted that the various audio objects can be successfully handled with respect to the bit-rate and the sound quality by using the proposed two-step coding structure SAOC.

Harmonic elimination structures for Karaoke mode in Spatial Audio Object Coding scheme

In this paper, a modified SAOC (Spatial Audio Object Coding) scheme with harmonic elimination structure is proposed. The proposed structure improves the quality of vocal-removed sound and well removes a vocal object using the harmonic information of the vocal object. Subjective and objective evaluation results show the proposed scheme is superior to the conventional ones.

Binaural decoding for efficient multi-channel audio service in network environment

In this paper, we proposed the binaural decoding in sound source location coefficient coding to focus on the reduction of the complexity. The proposed binaural decoding is implemented by convolution between the gain factors of the multi-channel audio signals generated by the spatial parameters and the HRTF coefficients in frequency domain. Compared with the typical binaural decoding in time domain, the proposed method can greatly reduce the complexity as about 90 %.

Efficient Transient Signal Detection in Spatial Cue Based Multi-Channel Audio Coding

This paper proposed the method that can efficiently detect the transient component existing in the multi-channel audio signal and accordingly extract spatial cues in order to improve the performance of the spatial cue based multi-channel audio coding. The proposed transient signal detection algorithm was implemented to use energy as well as the input signal envelope so as to successfully detect both the general transient signal and the long-duration transient signal. And it was found that the proposed method detected the transient signal more efficiently than the transient detection method using only the existing envelope through the detection of the actual transient signal.

Mastering Signal Processing with Residual Coding Scheme in Spatial Audio Object Coding

This paper presents the mastering signal processing with the residual coding scheme in spatial audio object coding. The proposed method can eliminate the difference between the original down-mix signal and the compensated down-mix signal and enhance the sound quality, successfully. Experimental result shows that the proposed method can greatly improve the performance of the original mastering signal processing and the sound quality of the proposed method is almost same with that of the output signal decoded with the original down-mix signal.

Vocal Removal From Multiobject Audio Using Harmonic Information for Karaoke Service

Interactive audio services (IASs) usually provide users with audio editing functionality and they can render their own sounds according to their preference. For IASs, the spatial audio object coding (SAOC) is an appropriate multichannel coding tool that satisfies most of the required functionalities with relatively low bit rate. Nevertheless, the SAOC usually fails to remove a specific object successfully, especially the vocal object in the case of the Karaoke service. In addition, to expand the service to mobile environments, lower bit rate and complexity are required. Thus, we propose a new SAOC vocal harmonic coding technique to improve the background music quality in the Karaoke service. Namely, utilizing the harmonic information of the vocal object, we removed the harmonics of the vocal object remaining in the background music. Our experimental results confirm that the background music quality is improved by the proposed algorithm even with the low bit rate and complexity.