Lars Liljeryd

Last updated

Lars "Stockis" Liljeryd (1951-2020) was a Swedish audio and medical engineer, inventor, and entrepreneur. He is noted for his pioneering work in the development of the audio compression technology called AAC, which revolutionized audio processing in portable music, video, and streaming media devices. [1] He was one of the founders of the startup company called Coding Technologies.

Contents

Liljeryd was also a musician.

Biography

Liljeryd was born in 1951 in Stockholm, Sweden. [2] He began his career as a recording engineer. [3] His break came after a North Sea oil exploration team sought his help to clarify divers’ communication underwater. [3] For this project, Liljeryd developed a digital pitch-shifter that transformed the helium-induced high pitched squeaks of the divers back to comprehensible levels so that they are able to communicate better with team members on the surface. [3] This technology launched his interest and success in digital audio compression.

Liljeryd developed the RX4000, a plate reverberation, for Stocktronics. [4] Clients that purchased this system include the Swedish Naval Diving Center at Berga and the Norwegian DDVS Norskald. [4]

New audio compression technology

In 1988, Liljeryd also invented a method that clarified sound and picture information electronically, including the approach that carry out the process. [5] This technology eliminated undesirable intermodulation products, providing a linear amplitude ratio. [6] The technique improved on the previous technology of compressing audio formats using “perceptual audio coding”, which eliminated parts of the original file that are missed by the human ear. [3] The original process, however, was complicated. To address this, Liljeryd introduced the compression technology that shrinks files through the elimination of high-pitched components and recreating these from information contained in low frequencies. [3] This technology called AACPlus was introduced in 2001 and became the basis of the MPEG-4 High Efficiency AAC, which was standardized in 2003. For his work on HE-AAC, Liljeryd - together with Kristofer Kjörling, and Martin Dietz - received the IEEE Masaru Ibuka Consumer Electronics Award in 2013. [7]

Liljeryd was a finalist in the European Inventor Award 2017 for developing a new method of compressing digital audio files called Spectral Band Replication (SBR). [8] This concept, which was produced into a real-world application by a team of engineers, improved existing coding formats such as MP3 and the Advanced Audio Coding (AAC). [9] This technology allowed better and more affordable digital audio compression, addressing the challenges that came with limited bandwidth and storage space. [9]

Adoption

Through Coding Technologies, Liljeryd’s techniques had been adopted by mobile phone operators, XM Satellite Radio Service, and the team behind the Motion Picture Experts Group (MPEG), among others. The company was also helping China build a digital multimedia platform that will serve as their alternative to DVD. [3]

In the medical field, Liljeryd was part of the group of inventors who developed the non-linear glucose transform (NLGT), a system that provides accurate representation of glycemic information. [10]

Music career

Liljeryd also played drums. In 1980, he participated as engineer and percussionist on the Hans Edler album Jukebox Graffiti Vol. 4 on the Europe Record label. [2]

Related Research Articles

A codec is a device or computer program that encodes or decodes a data stream or signal. Codec is a portmanteau of coder/decoder.

In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder.

<span class="mw-page-title-main">Digital video</span> Digital electronic representation of moving visual images

Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises a series of digital images displayed in rapid succession, usually at 24, 30, or 60 frames per second. Digital video has many advantages such as easy copying, multicasting, sharing and storage.

<span class="mw-page-title-main">Lossy compression</span> Data compression approach that reduces data size while discarding or changing some of it

In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size for storing, handling, and transmitting content. The different versions of the photo of the cat on this page show how higher degrees of approximation create coarser images as more details are removed. This is opposed to lossless data compression which does not degrade the data. The amount of data reduction possible using lossy compression is much higher than using lossless techniques.

<span class="mw-page-title-main">MP3</span> Digital audio format

MP3 is a coding format for digital audio developed largely by the Fraunhofer Society in Germany under the lead of Karlheinz Brandenburg, with support from other digital scientists in other countries. Originally defined as the third audio format of the MPEG-1 standard, it was retained and further extended—defining additional bit rates and support for more audio channels—as the third audio format of the subsequent MPEG-2 standard. A third version, known as MPEG-2.5—extended to better support lower bit rates—is commonly implemented but is not a recognized standard.

MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s without excessive quality loss, making video CDs, digital cable/satellite TV and digital audio broadcasting (DAB) practical.

<span class="mw-page-title-main">MPEG-2</span> Video encoding standard

MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, which permit storage and transmission of movies using currently available storage media and transmission bandwidth. While MPEG-2 is not as efficient as newer standards such as H.264/AVC and H.265/HEVC, backwards compatibility with existing hardware and software means it is still widely used, for example in over-the-air digital television broadcasting and in the DVD-Video standard.

Transform coding is a type of data compression for "natural" data like audio signals or photographic images. The transformation is typically lossless on its own but is used to enable better quantization, which then results in a lower quality copy of the original input.

<span class="mw-page-title-main">Video codec</span> Digital video processing

A video codec is software or hardware that compresses and decompresses digital video. In the context of video compression, codec is a portmanteau of encoder and decoder, while a device that only compresses is typically called an encoder, and one that only decompresses is a decoder.

Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. It was designed to be the successor of the MP3 format and generally achieves higher sound quality than MP3 at the same bit rate.

<span class="mw-page-title-main">Karlheinz Brandenburg</span> German electrical engineer and mathematician

Karlheinz Brandenburg is a German electrical engineer and mathematician. Together with Ernst Eberlein, Heinz Gerhäuser, Bernhard Grill, Jürgen Herre and Harald Popp, he developed the widespread MP3 method for audio data compression. He is also known for his elementary work in the field of audio coding, the perception measurement, the wave field synthesis and psychoacoustics. Brandenburg has received numerous national and international research awards, prizes and honors for his work. Since 2000 he has been a professor of electronic media technology at the Technical University Ilmenau. Brandenburg was significantly involved in the founding of the Fraunhofer Institute for Digital Media Technology (IDMT) and currently serves as its director.

<span class="mw-page-title-main">Spectral band replication</span> Low bitrate digital audio enhancement technique

Spectral band replication (SBR) is a technology to enhance audio or speech codecs, especially at low bit rates and is based on harmonic redundancy in the frequency domain.

<span class="mw-page-title-main">High-Efficiency Advanced Audio Coding</span> Audio codec

High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio defined as an MPEG-4 Audio profile in ISO/IEC 14496–3. It is an extension of Low Complexity AAC (AAC-LC) optimized for low-bitrate applications such as streaming audio. The usage profile HE-AAC v1 uses spectral band replication (SBR) to enhance the modified discrete cosine transform (MDCT) compression efficiency in the frequency domain. The usage profile HE-AAC v2 couples SBR with Parametric Stereo (PS) to further enhance the compression efficiency of stereo signals.

MPEG-4 Part 2, MPEG-4 Visual is a video compression format developed by the Moving Picture Experts Group (MPEG). It belongs to the MPEG-4 ISO/IEC standards. It uses block-wise motion compensation and a discrete cosine transform (DCT), similar to previous standards such as MPEG-1 Part 2 and H.262/MPEG-2 Part 2.

Parametric stereo is an audio compression algorithm used as an audio coding format for digital audio. It is considered an Audio Object Type of MPEG-4 Part 3 that serves to enhance the coding efficiency of low bandwidth stereo audio media. Parametric Stereo digitally codes a stereo audio signal by storing the audio as monaural alongside a small amount of extra information. This extra information describes how the monaural signal will behave across both stereo channels, which allows for the signal to exist in true stereo upon playback.

<span class="mw-page-title-main">MPEG-4 SLS</span> Extension to the MPEG-4 Audio standard

MPEG-4 SLS, or MPEG-4 Scalable to Lossless as per ISO/IEC 14496-3:2005/Amd 3:2006 (Scalable Lossless Coding), is an extension to the MPEG-4 Part 3 (MPEG-4 Audio) standard to allow lossless audio compression scalable to lossy MPEG-4 General Audio coding methods (e.g., variations of AAC). It was developed jointly by the Institute for Infocomm Research (I2R) and Fraunhofer, which commercializes its implementation of a limited subset of the standard under the name of HD-AAC. Standardization of the HD-AAC profile for MPEG-4 Audio is under development (as of September 2009).

MPEG Surround, also known as Spatial Audio Coding (SAC) is a lossy compression format for surround sound that provides a method for extending mono or stereo audio services to multi-channel audio in a backwards compatible fashion. The total bit rates used for the core and the MPEG Surround data are typically only slightly higher than the bit rates used for coding of the core. MPEG Surround adds a side-information stream to the core bit stream, containing spatial image data. Legacy stereo playback systems will ignore this side-information while players supporting MPEG Surround decoding will output the reconstructed multi-channel audio.

A video coding format is a content representation format of digital video content, such as in a data file or bitstream. It typically uses a standardized video compression algorithm, most commonly based on discrete cosine transform (DCT) coding and motion compensation. A specific software, firmware, or hardware implementation capable of compression or decompression in a specific video coding format is called a video codec.

<span class="mw-page-title-main">Audio coding format</span> Digitally coded format for audio signals

An audio coding format is a content representation format for storage or transmission of digital audio. Examples of audio coding formats include MP3, AAC, Vorbis, FLAC, and Opus. A specific software or hardware implementation capable of audio compression and decompression to/from a specific audio coding format is called an audio codec; an example of an audio codec is LAME, which is one of several different codecs which implements encoding and decoding audio in the MP3 audio coding format in software.

Coding Technologies AB was a Swedish technology company that pioneered the use of spectral band replication in Advanced Audio Coding. It is a major provider of audio compression technologies for digital broadcasting.

References

  1. ↑ Office, European Patent. "Lars Liljeryd (Sweden)". www.epo.org. Retrieved 2023-04-04.
  2. 1 2 "Lars "Stockis" Liljeryd". Discogs. Retrieved 2023-04-04.
  3. 1 2 3 4 5 6 Borland, John. "The sound of science". CNET. Retrieved 2023-04-14.
  4. 1 2 Subnotes. Berkeley, CA: Windate Enterprises. 1987. p. 9.
  5. ↑ Index of Patents Issued from the United States Patent and Trademark Office, Volume 1: A-L. Washington, D. C.: United States Patent and Trademark Office. 1988. p. 1410.
  6. ↑ Larsen, Erik; Aarts, Ronald M. (200). Audio Bandwidth Extension: Application of Psychoacoustics, Signal Processing and Loudspeaker Design. Hoboken, NJ: John Wiley & Sons. p. 249. ISBN   0-470-85864-8.
  7. ↑ "IEEE Level Awards" (PDF). IEEE. Retrieved April 29, 2023.
  8. ↑ Office, European Patent. "Lars Liljeryd (Sweden)". www.epo.org. Retrieved 2023-04-14.
  9. 1 2 "Lars Gustaf Liljeryd (SE): Digital Audio Compression". Films Media Group. Retrieved 2023-04-14.
  10. ↑ Acton, Ashton (2013-06-21). Advances in Proinsulin Research and Application: 2013 Edition. Atlanta, GA: ScholarlyEditions. p. 741. ISBN   978-1-4816-8380-7.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.