High Definition Compatible Digital

High Definition Compatible Digital (HDCD) is a proprietary audio encode-decode process that claims to provide increased dynamic range over that of standard Red Book audio CDs, while retaining backward compatibility with existing compact disc players.

High Definition Compatible Digital
Media typeOptical disc
CapacityTypically up to 700 MB
Read mechanism780 nm wavelength semiconductor laser
Developed byPacific Microsonics Inc./Microsoft
UsageAudio storage
Extended fromRed Book

Originally developed by Pacific Microsonics, the first HDCD-enabled CD was released in 1995.[1] In 2000, the technology was purchased by Microsoft, and the following year, there were over 5,000 HDCD titles available.[2] Microsoft's HDCD official website was discontinued in 2005; by 2008, the number of available titles had declined to around 4,000.[1]

A number of CD and DVD players include HDCD decoding, and versions 9 and above of Microsoft's Windows Media Player on personal computers are capable of decoding HDCD.

HDCD was a favorite for several artists such as Joni Mitchell, Neil Young and the Beach Boys, all of whom have had many titles in their catalogs reissued in this format.

Technical overview

HDCD encodes the equivalent of 20 bits worth of data in a 16-bit digital audio signal by using custom dithering, audio filters, and some reversible amplitude and gain encoding: Peak Extend, which is a reversible soft limiter; and Low Level Range Extend, which is a reversible gain on low-level signals. There is thus a benefit at the expense of a very minor increase in noise.[3]

The claim that the encoding process is compatible with ordinary CD players (without audible distortion) is disputed: not being able to decode the peak soft limiting, a normal CD player will output distorted peaks.[4]

History

HDCD technology was developed between 1986 and 1991 by "Prof." Keith O. Johnson and Michael "Pflash" Pflaumer of Pacific Microsonics Inc. It was made publicly available as HDCD-enabled audio CDs (often identifiable by the HDCD logo printed on the back cover) in 1995.

Between 1996 and 1999 Pacific Microsonics VP of OEM Sales, Steve Fields, made over 20 trips to Japan, visiting Sanyo, Burr-Brown Japan and major audio companies, with the intent of licensing the HDCD technology. In 1998, Burr-Brown (now part of Texas Instruments) and Sanyo Electronics of Japan introduced low cost D-to-A converters with HDCD decoding included, allowing HDCD to be used in CD and DVD players in the $100 range. HDCD algorithms were included in DVD chips from many IC makers including Motorola and C-Cubed, allowing HDCD to be offered by mass-market DVD player makers such as Panasonic and Toshiba.

In 2000, Pacific Microsonics folded and Microsoft acquired the company and all of its intellectual property.[5][6] Microsoft discontinued the official HDCD website in 2005.

In January 2007, there were roughly the same number of titles available on SACD as on HDCD-encoded CDs.

Hardware players

A number of manufacturers offer players with HDCD capability. Some Panasonic DVD players and the Oppo line of players all feature HDCD decoding.[7] [8] Several Yamaha Blu-ray players[9] [10] as well as Emotiva CD players [11] decode HDCD.

Software players

Windows Media Player

Since version 9 of Microsoft's Windows Media Player (WMP) HDCD enabled CDs can be played on personal computers fitted with a 24-bit sound card.[12][13]

With some HDCD discs and some DVD players using WMP, the first track may not be recognized as HDCD, but all subsequent tracks are. This is because HDCD has a control signal, and if the signal is not detected by WMP at the beginning of the song, the HDCD decoder is not activated.

Other software

In 2007, a member of the Doom9 forum authored a Windows CLI utility, hdcd.exe,[14] to extract and decode the HDCD data in 16-bit WAV files ripped from HDCD discs. This utility writes 24-bit WAV output files with four bits of padding per sample. The author of the utility decided not to make the source code publicly available as the HDCD technology is patented.[15]

Illustrate's dBpoweramp Music Converter, a Windows GUI program, has an HDCD DSP effect that acts as a front-end to the utility listed above.[16]

A plugin[17] is available for foobar2000 that will decode HDCD data in any 16-bit PCM passed through it, resulting in a 20-bit PCM stream.

FFmpeg's libavfilter includes an HDCD filter as of FFmpeg 3.1 (June 2016) that will convert 16-bit PCM with HDCD data to 20-bit PCM.[18]

An open-source HDCD decoder library exists as libhdcd.[19]

See also

References
  1. "Home Technology eMagazine - Classic Home Toys Installment #19 The Final CD Format: HDCD". HomeToys. 30 November 2008. Archived from the original on 21 June 2015. Retrieved 5 August 2012.
  2. "HDCD (High Definition Compatible Digital) from Pacific Microsonics". TimeForDVD.com. 23 February 2002. Retrieved 5 August 2012.
  3. Johnson, Keith O.; Pflaumer, Michael W. (November 1996). "Compatible Resolution Enhancement in Digital Audio Systems". Audio Engineering Society. Retrieved 2012-08-22.
  4. "The HDCD Enigma". Audiomisc.co.uk. Retrieved 2012-08-05.
  5. US 5479168
  6. US 5872531
  7. "Universal Network 3D Blu-ray Players - Buy Direct from the Manufacturer". OPPO Digital. Retrieved 2012-08-05.
  8. "Unofficial OPPO UDP-203 Frequently Asked Questions". AVSForum. Retrieved 2017-03-03.
  9. "Yamaha BD-A1060 Universal Blu-Ray Player Review". Secrets of Home Theater and High Fidelity. 2016-11-14. Retrieved 2017-03-04.
  10. "2 new Yamaha uni players - including one with balanced analog outputs". Steve Hoffman Music Forums. 2016-07-16. Retrieved 2017-03-04.
  11. "Emotiva ERC-3 Differential Reference CD Player/Digital Transport Review". Secrets of Home Theater and High Fidelity. 2014-09-02. Retrieved 2017-03-04.
  12. "Features of Windows Media Player 9 Series". Microsoft.com. Retrieved 2012-08-05.
  13. "Smart Jukebox Features". Microsoft.com. Retrieved 2012-08-05.
  14. utility
  15. "HDCD Software Decoder - Doom9's Forum". Forum.doom9.org. Retrieved 2012-08-05.
  16. dBPoweramp's DSP Effects page ; dBpoweramp's local help file
  17. "foobar2000 HDCD decoder component". Foobar2000.org. 2012-07-18. Retrieved 2012-08-05.
  18. "June 27th, 2016, FFmpeg 3.1 "Laplace"". FFmpeg.org. Retrieved 2 July 2016.
  19. "libhdcd - An HDCD decoder library". Retrieved 21 August 2016.
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