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Patent, Copyright, Source Code, ITC, IPR Expert Witness

John Strawn, Ph.D.

John Strawn, Ph.D.

S Systems Inc.
15 Willow Avenue

Larkspur, California 94939

Phone(415) 927-8856


► Contact John Strawn, Ph.D.

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Dr. Strawn (Ph.D., Stanford) is a seasoned expert witness specializing in patent litigation with experience in District Court, the International Trade Commission, and the US Patent Office. He also handles trade secret and copyright litigation involving software. He has been deposed 19 times, testified at trial 3 times including the landmark case Lucent v Microsoft, and submitted 10 declarations in 17 IPR filings. Dr. Strawn handles validity and infringement for both plaintiffs and defendants. Based on his own research, he writes his own reports and declarations.


Dr. Strawn's expertise includes:

Testifying expert witness (including expert reports, deposition).
Software analysis for litigation including patent, copyright, trade secret, software theft.
Prior art investigation and research for District Court litigation and IPRs.
Assembler, object-oriented, C, C++, HTML, XML, Java, Javascript, SQL.
Implement/optimize signal processing algorithms: Fourier transform (FFT), discrete cosine transform (DCT), DTMF, speech synthesis.
Port/optimize audio compression algorithms: AC-3, MP-3, AAC.
Implement audio algorithms: reverberator, pitch shifter, sample rate converter, compressor, filter, flanger, 3-d audio (Dolby surround), dither.
Implement music synthesis (additive, physical modeling, wavetable, FM).
Create bug-free software from academic signal processing research.
Work in floating- and fixed-point math.
Extensive experience optimizing code in assembler
PC, Mac, Unix.
DSP processor architectures: Motorola 56000, 56300, and 56800 families; TI TMS320C10 and TMS320C54 family; Code Composer Studio; Analog Devices 21xx family and TigerSharc; VLIW; custom processors; I learn new processor architectures quickly.
Embedded processors: Hitachi SH-DSP, SH3-DSP, SH-4, and SH-5; ARM7/ARM9; configurable processors (Tensilica).
Processor architecture.
Debugging hardware prototypes.
Media networks, such as AES/EBU (IEC 60958), IEEE-1394/FireWire, AV/C, 61883, mLAN, and others.
File downloading.
Practical audio experience in live sound and in studios.

Litigation Support Services

I do my own research and write my own reports.

Areas of Expertise

Additional Expertise:

Streaming, Compression, Android, Apple, C, C++, DSP, Dutch, Fortran, French, German, HTML, IP, IPR, ITC investigations, Inter Partes Reviews, Internet, Internet protocol, JPEG, Japanese, Java, Javascript, MPEG, Markman, SQL, USPTO, XML, algorithm, audio, call center, cell phone, cinema, claim chart, class action litigation, client/server, compression (MP-3, MPEG-4, AAC used in iTunes, AC-3, FLAC), computer, copyright litigation involving software, declaration, deposition, digital camera, digital signal processing, embedded, expert report, file downloading, handheld device (e.g. medical), iOS, iPhone, infringement analysis, invalidity, laptop, mathematics, media: audio, music, speech, video, mobile device, multimedia, music, music instrument, patent litigation, prior art, processor architecture, protocol, ring tone, schematic, software, source code, source code comparison, speech, streaming, synthesizer, tablet, television, trade secret litigation, transform, tutorial, user interface, video (MPEG), video game.


Seasoned testifying expert with litigation experience (patent, copyright, trade secret, class action), skilled at explaining complex ideas to attorneys and juries. Several decades involvement in software, digital audio, digital music, digital signal processing, and processor architecture. Successful independent software consultant in high-level languages and assembly language. Stanford Ph.D. Former Fulbright Scholar. Prolific author. Experienced manager with long-range research and development experience. Facile with foreign languages and working with people from outside the USA.

Areas Served

All States

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Professional Experience

S Systems, Inc. (1992-present; 1986-1988); Owner and Full-time Consultant.
Yamaha Music Technologies USA;1989-1991: President; 1987-1989: Vice President.
Lucasfilm/Droid Works (1985-1986); Programmer.
Stanford University (1976-1985), Doctoral Student.
Revox (1972); Summer intern.

Legal Experience & Services

19 depositions to date, 3 times testimony at trial, 10 IPR declarations in 17 IPR filings. Patent litigation, ITC investigations, Inter Partes Reviews, USPTO declarations, class action litigation, trade secret litigation, copyright litigation involving software. Expert reports, declarations, prior art research and analysis, infringement analysis (e.g., analyze devices, documents; source code analysis, source code comparison), claim charts, tutorials, Markman hearings.

Technical areas include software and source code; computers, laptops, cell phones, mobile devices, handheld devices (e.g., medical); processor architecture; user interfaces; media: audio, music, speech, video; compression (e.g., MPEG, MP3); digital signal processing, mathematics, algorithms; file downloading, file streaming, client/server; protocols such as internet protocol (IP); video games. Links available online (


Fellow (1996) and Life Member, Audio Engineering Society (AES).
Convention Co-chair, 2008 AES Convention, San Francisco.
Convention Chair, 2006 AES Convention, San Francisco.
Convention Chair, 2004 AES Convention, San Francisco. Recipient of an Anderton Award, Pro Sound News, December 2004, p. 30.
Technical Papers co-chair, 2002 AES convention, Los Angeles.
Technical Papers chair, 1992 AES Convention, San Francisco (first AES San Francisco Convention).
Conference Chair, 1987 AES International Conference on Music and Digital Technology (Los Angeles).
Elected member of the AES Board of Governors, 1992-1994; again 2005-2007.
Chair, AES Convention Policy Committee, 2006-2008.
Former member of review board, Journal of the Audio Engineering Society.
Assistant Editor, Computer Music Journal, (MIT Press), 1978-1982.
Co-founder (1980), International Computer Music Association.
Founder and Series Editor (1984-1996), The Computer Music and Digital Audio Series.
Honorary Member (1998-2019), The Midi Association, formerly Midi Manufacturers Association (MMA).
Conference paper reviewer for many International Computer Music Conferences (ICMC).
Member, Acoustical Society of America. Life Senior Member, IEEE.


My experience includes writing and debugging complicated software in low-level (assembly) language and high-level languages such as Fortran, Algol derivatives, C, and C++. My assembly-language work has focused on digital signal processors from families such as Motorola 56000, Texas Instruments TMS320, and the Analog Devices 2100, Sharc, and TigerSharc. I have worked in "very-long instruction word" (VLIW) processors including at Lucasfilm. My processor experience further includes generalized processors such as ARM, MIPs, and Pentium, and extensible processors such as those from Tensilca and Stretch. As a software programmer I am known for writing bug-free, reliable code. As a software programmer I work closely with hardware (although I do not design hardware). My code typically uncovers at least one new bug in the hardware.

I bring the same discipline to my work as an expert witness, in analyzing patents, in analyzing prior art, and in analyzing software.

Awards & Honors

Fulbright Scholar, Technical University of Berlin, Germany, 1973-1974, renewed 1974-1975.
Thomas Watson IBM Fellow, Europe and Japan, 1975-1976.
Keynote Speaker, November 1996 Audio Engineering Society Convention.

Seminars & Training

I have given training ranging from one-hour tutorials through day-long seminars at various public venues including Microprocessor Forum, Embedded Processor Forum, and the Audio Engineering Society.


"Approximation and Syntactic Analysis of Amplitude and Frequency Functions for Digital Sound Synthesis." Computer Music Journal 4(3):3-22, 1980.
Modeling Musical Transitions. Ph.D. Thesis, Stanford University, 1985. 243 pp.
(with C. Roads). Foundations of Computer Music. MIT Press, 1985. 600 pp.
Digital Audio Engineering: An Anthology. Madison, WI: A-R Editions, 1985. 144 pp.
Digital Audio Signal Processing: An Anthology. Madison: A-R Editions, 1985. 283 pp.
"Orchestral Instruments: Analysis of Performed Transitions." Journal of the Audio Engineering Society 34(11):867-80, 1986. "Editing Time-varying Spectra." Journal of the Audio Engineering Society 35(5):337-51, 1987.
"Analysis and Synthesis of Musical Transitions Using the Discrete Short-time Fourier Transform." Journal of the Audio Engineering Society 35(1/2):3-14, 1987.
"Implementing Table Lookup Oscillators for Music with the Motorola DSP56000 Family." Presented at the 85th Convention of the AES, 1988. Preprint No. 2716.
"Digital Audio Representation and Processing." Multimedia Systems, edited by John F. Koegel. ACM and Addison-Wesley, 1993. "Technological Change: The challenge to the audio and music industries” (written version of AES keynote address). Journal of the Audio Engineering Society, March 1997.
“AES White Paper: Networking Audio and Music using Internet2 and Next Generation Internet Capabilities.” (with James Grunke, Ben Novak, Bruce Pennycook, Zack Settel, Phil Wiser, and Wieslaw Woszczyk). Journal of the Audio Engineering Society 47(4):300-310, April 1999. Presented (with Betsy Cohen and AES President Marina Bosi) to White House National Economic Council, December 1998.
(with Yamaha's Mike Overlin). “Playing with Fire,” Electronic Musician, May 2003, pp. 31-38 (on audio networking over 1394).

Professional References

References for work as testifying expert witness and software engineer from industry, academia, and the legal profession available on request.


Ph.D., Stanford University, 1985
B. Mus., Oberlin, 1973

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