Johnston, James

What He Does

JJ is presently the Chief Scientist for DTS, Inc, working from Kirkland, Washington. DTS provides the high-quality audio system for BlueRay disc, and is an industry leader in audio coding, codec preprocessing, multichannel audio, loudness control, and other advanced signal processing algorithms for audio.

His current interests include loudspeaker pattern analysis and control, loudness modelling, room simulation, stereo image control and analysis, filter design, speech coding, audio and speech testing methodology and execution, and implementation concerns in audio processing.

He is the primary inventor and architect for a variety of signal processing algorithms related to room correction, loudness processing, perceptual modelling of audio, audio coding, audio soundfield perception and presentation, and standards and ancillary mathematics and science related to audio issues.

His prior contributions include MPEG-2 AAC (Advanced Audio Coding) standard, developed in collaboration with Fraunhofer IIS and other experts in the field of audio compression, MPEG-2 AAC is a reworking of the original AT&T Perceptual Audio Coder (PAC), done with Anibal Ferriera, co-invention and standardization of the well-known "MP3" algorithm, a variety of loudness estimation and control methods, automatic speaker and room correction systems, room and acoustic simulators, and invention of a perceptual soundfield reconstruction system to capture the "sound" of an actual performance venue and reconstruct the perceptual cues of the venue in a fashion that can be conveyed in a small (presently 5) number of conventional, independent audio channels multichannel audio presentation, and audio coding (bitrate reduction).

Interests

JJ's current research interests include acoustic scene modelling, loudspeaker design, loudspeaker pattern control, cochlear modelling, masking threshold models, stereo imaging models and stereo imaging sensitivity models, methods of reproducing soundfields either literally or perceptually, microphone and soundfield capture techniques, both actively steered and time-invariant, and speech and audio coding methods in general. He completed the first perceptual soundfield recordings, which received exceptional reviews from the listener and enthusiast community, before retiring from AT&T.

Vita

JJ is currently employed at DTS, Inc in Kirkland, Wa, where he is working on a variety of acoustical modelling, preprocessing and postprocessing algorithms for audio capture, analysis, control, and presentation.

He joined DTS, Inc from his position at Neural Audio when Neural was acquired by DTS. Prior to that, he worked for 5 years at Microsoft Corporation in the "Codecs", "Core Media Processing" and finally the video services groups as Audio Architect.

He is retired from AT&T Labs - Research, quartered at Florham Park, NJ, Speech Processing Software and Technology Research Department. Before that, he was employed by AT&T Bell Laboratories, in the Acoustics Research Department under Dr. J. L. Flanagan, and in the Signal Processing Research Department.

He started his career working on using analog signal processing to do speech coding (APCM, ADPCM, SBC) for testing of algorithms, sampling rates, and quantizer resolutions. His first IEEE paper detailed the hardware construction of an ADPCM implementation using analog multipliers and integrators to provide both step-size and predictor "calculation", in a form that allowed sampling rate and quantizer resolution changes.

Since then, he has worked in analog signal processing, speech coding, voice privacy, quadrature mirror filter design, and perceptual coding of both audio and images. During this work on perceptual audio coding, he has been the primary investigator of the early PXFM audio coder which was reported on at the ASSP Digital Audio Meeting in Mohonk, NY in 1986 and a co-inventor and standards proponent of the ASPEC algorithm, the quality leader in the MPEG-1 audio competition.

During this time, he also did an investigation of coding of still-frame images using a forward-driven perceptual model with Dr. R. J. Safranek, also of AT&T Bell Laboratories. This image coder, called PIC (for Perceptual Image Coder), used very simple techniques to provide state of the art still-image compression.

Perceptual coding, as compared to source coding, pays primary attention to the intended reciever or destination of the signal, rather than the source or source model of the signal. This destination is usually the human being. By eliminating imperceptable information in the signal, compression rates that are substantially better than the usual source coding rates are achieved, with substantially more mean squared error, but better percieved quality than the source coder.

Until 2002, he was the primary researcher and inventor of AT&T's contributions to the MPEG-2 AAC audio coding algorithm. He also represented AT&T in the ANSI accredited group X3L3.1, and X3L3.1 in the ISO-MPEG-AUDIO (AAC) arena in support of the AAC algorithm.

Awards and Societies

In 2006, he was awarded the J. L. Flanagan Signal Processing Field Award from the IEEE Signal Processing Society for his work on creation and standardization of perceptual audio coding.

In 1997, JJ was elected a Fellow of the Audio Engineering Society for his work on perceptual coding of audio.

He became a Senior Member of the IEEE, and recieved an AT&T Technology Medal and AT&T Standards Award in 1998.

In February 2001, he recieved a New Jersey Inventor of the Year award for his contributions to MP3 and audio coding in general.

He was elected a Fellow of the IEEE in 2002.

He received his BSEE and MSEE from Carnegie-Mellon University, with side interests in mathematics, audio, radio broadcasting and coherent image signal processing.

Copyright 2009 j.d.johnston@ieee.org, all rights reserved.