Yutaka Kamamoto

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The recently standardized 3GPP codec for Enhanced Voice Services (EVS) offers new features and improvements for low-delay real-time communication systems. Based on a novel, switched low-delay speech/audio codec, the EVS codec contains various tools for better compression efficiency and higher quality for clean/noisy speech, mixed content and music,(More)
The ITU-T Recommendation G.711 is the benchmark standard for narrowband telephony. It has been successful for many decades because of its proven voice quality, ubiquity and utility. A new ITU-T recommendation, denoted G.711.0, has been recently established defining a lossless compression for G.711 packet payloads typically found in IP networks. This paper(More)
Optical communication through light-emitting diodes (LEDs) and video cameras is rapidly gaining attention due to the increasing pervassiveness of those devices, and because of its potential data capacity. However, the communication quality is greatly compromised by the low resolution of the imaging sensor which produces blurred images of the LEDs at long(More)
MPEG-4 Audio Lossless Coding (ALS) is a new extension of the MPEG-4 audio coding family. The ALS core codec is based on forward-adaptive linear prediction, which offers remarkable compression together with low complexity. Additional features include long-term prediction, multichannel coding, and compression of floating-point audio material. In this paper(More)
This paper describes a new search algorithm that quickly finds interchannel relationships between a coding channel and a reference channel in the multichannel coding tool of the MPEG- 4 Audio Lossless Coding (ALS) international standard. The algorithm has tree structure and can reduce data size with significantly smaller computation load than that of the(More)
We propose a novel principle based on Complex Spectrum Circle Centroid (CSCC) for restoring complex spectrum of the target signal from multiple microphone input signals in a noisy environment. If noise arrives at multiple microphones with different time delays relative to the target signal, the observed noisy signals lie on a circle in the complex spectrum(More)
ITU-T Rec. G.711 is widely used for the narrow band speech communication. ITU-T has just established a very low complexity and efficient lossless coding standard for G.711, called G.711.0 - Lossless compression of G.711 pulse code modulation. This paper introduces some coding technologies newly proposed and applied to the G.711.0 codec, such as Plus-Minus(More)
This paper describes two low-complexity tools used for the new ITU-T recommendation G.711.0, the lossless coding of G.711 (A-law/μ-law logarithmic PCM) speech data. One is an algorithm for quantizing the PARCOR/reflection coefficients and the other is an estimation method for the optimal prediction order. Both tools are based on a criterion that(More)