Konstantinos Konstantinides An Introduction to Super Audio CD and DVD-Audio or many, the audio CD Table 1. Main parameters in DVD-Audio, SACD, and audio CD recordings. is considered the most successful new format Parameter DVD-Audio SACD CD in consumer electron- 16-, 20-, or 24-b Fics. Since its introduc Audio coding 1-b DSD 16-b LPCM - LPCM tion in 1982, the CD has become the 44.1, 48, 88.2, 96, distribution medium of choice for Sampling rate 2,822.4 kHz 44.1 kHz both music and data. Using a sam- 176.4, or 192 kHz pling frequency of 44.1 kHz, analog Channels 1-6 2-6 2 audio is sampled and converted to pulse code modulated (PCM) sam- Compression Yes (MLP) Yes (DST) None ples. Each sample has 16 b of resolu- tion and provides a signal-to-noise ra- Content protection Yes Yes No tio in excess of 96 dB. Audio CDs use Playback time 62-843 min* 70-80 min 74 min no compression; however, a cross-in- terleaved Reed-Solomon code Frequency response DC-96 kHz DC-100 kHz DC-20 kHz (CIRC) allows audio CDs to satisfy Dynamic range Up to 144 dB Over 120 dB 96 dB the need for error detection and cor- rection during playback. *For 62 min, we assume f s = 96 kHz, 20-b samples, and five channels. For 843 min, we In 1997, the introduction of assume f s = 44. 1 kHz, 16-b samples, and one channel. DVD-Video provided not only supe- rior video quality but also allowed consumers to experience and enjoy multichannel surround sound in the (DSD), and direct stream transfer JVC and the Meridian Group, pres- home. DVD movies do provide mul- coding. Unlike DVD-Audio, SACD ents an overview of the DVD-Audio tichannel audio, but it is stored com- does not use PCM encoding. The idea specification. The authors place spe- pressed using the lossy Dolby digital behind DSD is to remove the cial emphasis into the design and im- or MPEG-audio formats. The sam- front-end and back-end decimation plementation of the MLP coder, pling rate for compressed audio in the and interpolation filters and directly especially as it relates to the coding of DVD-Video format is 48 kHz. record 1-b data, sampled at approxi- multichannel audio. The DVD-Audio specification al- mately 2,822.4 kHz. At the end, ThesecondarticlebyE.Janssen lows for up to 24-b PCM data and DSD signals yield a dynamic range and D. Reefman, from Philips Re- uses the Meridian lossless packing greater than 120 dB. Table 1 summa- search Laboratories, introduces (MLP) algorithm to provide up to six rizes the key characteristics of audio SACD. Here, the authors place special channels of high-quality, multichan- CDs, SACD, and DVD-Audio. emphasis on the new challenges in dig- nel audio at sampling rates of up to 96 The purpose of the next two articles ital signal processing using DSD kHz for six channels or 192 kHz for is to present and highlight the latest streams. two channels. developments in consumer audio and I hope that readers will enjoy Super-audio CD (SACD), intro- specifically in DVD-Audio and reading both articles and that this duced in March 1999, integrates a va- SACD. Forum will stimulate a healthy and riety of new technologies, such as the The first article by B.H. Suzuki, N. interesting exchange of ideas in fu- hybrid disc, direct stream digital Fuchigami, and J.R. Stuart, from ture columns. JULY 2003 IEEE SIGNAL PROCESSING MAGAZINE 71 1053-5888/03/$17.00©2003IEEE Bike H. Kuzuki, Norihiko Fuchigami, and J. Robert Stuart DVD-Audio Specifications ince 1983 audio CD most interest for readers of this maga- the lossless compression must be (CD-DA) has been the zine. (MLP stands for Meridian used. As the name implies, MLP primary carrier for high- Lossless Packing and is a trademark of compresses data without any loss and Squality stereo music. In Dolby Laboratories Inc.) decompresses it into data that is ex- the intervening years opti- actly identical to the original LPCM cal media and signal processing tech- master. MLP enables any of the audio nologies have greatly advanced and en- Features of DVD-Audio formats permitted on DVD-Audio to abled the development of higher-den- Working Group 4 (WG4) of the play for longer than 74 min (on a sin- sity discs such as DVD (digital versatile DVD Forum developed the gle layer 4.7 GB disc). disc). DVD offers more than six times DVD-Audio Specification, and dur- DVD-Audio also supports the the capacity of CD. ing this effort they received 15 key re- sampling frequencies 44.1, 88.2, and quirements from the international The DVD Forum [1] has devel- 176.4 kHz for making good use of as- music industry, represented by ISC oped a family of specifications to ac- sets that may be issued on CD. (International Steering Committee). commodate both prerecorded DVD-Audio offers great flexibly The main features of DVD-Audio, (DVD-ROM) and recordable to producers by supporting not only which closely reflect these require- (DVD-R, RW, and RAM) applica- the high-bit/high-sampling parame- ments, are summarized below. tions. DVD-Video [2] and DVD- ters but also more conventional cod- Audio [3] are both applications of ing such as 44.1 kHz/16-b/two DVD-ROM. High-Quality Audio channel. Titles can be made in a wide DVD-Video provides a carrier The first requirement from artists, the variety of formats. for high-quality video assets, and its music industry, and listeners is to pro- specification reflects a balance be- vide sound quality that is superior to tween both data capacity and data CD and as close to the original master Attractive Multichannel rate for the sound and picture com- as possible. DVD-Audio meets this Surround ponents of a movie. By contrast, requirement flexibly by offering sev- Although DVD-Audio provides for DVD-Audio uses the capacity of eral options based on linear pulse super high-quality, two-channel au- DVD-ROM to provide a music car- code modulation (LPCM). By in- dio, perhaps its most attractive fea- rier with supreme audio quality and cluding options that increase both the ture is the support for high-quality better sound-field reproduction. sampling frequency and quantization multichannel sound. The superb The DVD-Audio Specification was word length, DVD-Audio offers four quality of sound field that can be drawnupincooperationwiththe times the frequency range and 256 achieved through exerting the whole music industry, which demanded times the resolution of CD. DVD- bit rate of DVD for audio data is very high-quality audio in stereo Audio supports: clearly superior to that obtained using and multichannel, multimedia func- L up to 192 kHz/24-b for two-chan- the lossy-compressed surround tions and security. nel stereo sound options of DVD-Video. The lossless coding scheme L up to 96 kHz/24-b for multichan- DVD-Audio also offers methods adopted in DVD-Audio is a key tech- nel (up to six channels). to enjoy multichannel music in nology that allows high-quality mul- In some combinations the audio two-channel listening environments tichannel music to be available on the can be stored on the disc as raw by providing backward compatibility huge, but still limited, capacity DVD LPCM. However, for efficient re- for the listener who has a two-channel disc. This article mainly focuses on cording of the huge data resulting speaker system or who may be using MLP Lossless [4] since it will be of from high-resolution multichannel, headphones. 72 IEEE SIGNAL PROCESSING MAGAZINE JULY 2003 A Variety of Supporting Copyright tions. As with CD-DA, index 0, and 1 Value-Added Contents Management System to 99 can be specified. Another important requirement for Illegal copying damages the rights of Besides audio data, a DVD-Audio this new generation medium is the content owners and so new generation disc can include still pictures, provision of a variety of value-added carriers must provide a credible protec- DVD-Video compatible content, and content to supplement the high-qual- tion system against illegal copying. so on. DVD-Video compatible con- ity audio experience. DVD-Audio of- DVD-Video compatible content tents are also represented as tracks at fers attractive value-added content: makes use of the content scramble sys- the user level. A “visual menu” may still pictures that can be enjoyed in tem (CSS) encryption method [5] that also be included if required. Figure 1 conjunction with the high-quality is used to protect DVD-Video movies. shows the user’s view of DVD-Audio. audio, DVD-video compatible con- For the high-quality audio, DVD-Au- For distinction, we call tracks for tent suitable for video clips such as dio adopts a newer copy protection sys- high-quality audio contents audio interviews, and visual menu for se- tem: content protection for pre- tracks and those for DVD-Video lecting songs or additional informa- recorded media (CPPM) [6]. Addi- compatible contents video tracks. tion. These features were developed tionally, audio data on a DVD-Audio by transplanting or expanding on discmaycontainan“audiowatermark” the multimedia capability of that enables downstream control of il- Internal Data Structure DVD-Video. legal copying. of DVD-Audio The internal data structure of Compatibility with DVD-Video A User’s View of DVD-Audio is somewhat different As will be explained later, DVD- from that implied by the user’s view.