Super Audio CD

The Super Audio Compact Disc, SACD for short or SA- CD is a disk and physically a special form of digital versatile disc (DVD), which was developed by Philips and Sony. The SACD uses a higher digital resolution of the audio signal as the audio CD and also provides the ability to store multi-channel ( surround sound ) without data reduction. It was designed as the successor to the audio CD (CD -DA) and competes with DVD-Audio, which has similar properties for several years.

Technology

On the SACD the audio in Direct Stream Digital (DSD ) format is available. This differs from the pulse code modulation technique (PCM ) technique of the audio CD or DVD-Audio. For the Direct Stream Digital format called Delta -sigma modulation is used. The word length of the digital audio signal is here only 1 bit, but at a sample rate of 2.8224 MHz ( 64 x 44.1 kHz). In contrast, lie on a conventional audio CD, the audio data in pulse - code modulation with 16 bit resolution at 44.1 kHz sampling rate before. Although for both encodings primarily delta-sigma analog -to-digital converters are used today, both methods differ fundamentally in the way of signal processing. The required during analog - to-digital conversion anti-aliasing filter - in particular, may result in the relatively low sampling rate of the audio CD to filter ringing effect (English for filter ringing) - can significantly with the much higher sampling rates of the delta-sigma modulation be interpreted in less annoying. Can also be dispensed with in the analog-to- digital conversion to the decimation filter, and in the digital- to-analog conversion in the terminal device to interpolation filter when using the conventional delta-sigma converter.

According to advertising claims of Sony / Philips is due

  • The significantly higher sampling frequency,
  • A larger upper frequency ( 50,000 Hz instead of 20,000 Hertz) and
  • A dynamic range of over 120 dB

Sound SACD already in stereo playback better than a conventional audio CD - a quality recording as well as providing a high quality stereo system. Assumptions from the high-end sector, DSD was superior to PCM format basically, so far could not prove itself. The tonal characteristics of the SACD can be realized also with PCM technique when determining the resolution of the dynamics and the crucial for the frequency range sampling frequency is increased accordingly, for example on 24 bits at 176.4 kHz. On the Blu- ray Disc, the pulse - code modulation is used increasingly.

Comparing the underlying technology of the pulse code modulation to that of the delta-sigma modulator ( conventional delta-sigma analog-to- digital converter ), the only difference in the absence of the sample rate converter ( downsampling ) at the output of delta-sigma modulator: in DSD format, the audio signal with low word width ( 1-bit) and a high sampling rate is stored. The band limitation that also suppresses the higher-frequency noise components is ( PCM output) integrated with conventional delta-sigma analog-to- digital converters by means of the digital filter directly after the delta-sigma modulator in the sample rate conversion, while in the DSD technique is only later, when the audio playback, made.

In addition, the SACD multichannel support ( surround sound ) with up to six channels. The SACD can - like the DVD - Audio - Save high-resolution multi-channel lossless. Compression methods, such as Dolby Digital or DTS, which are used for example in the DVD video, this can not. The multi-channel soundtrack on the SACD is optional: Some SACDs only include a high-resolution stereo track, so they do not use the multi-channel option.

There are some SACD player, stereo SACDs, but can not only play multi-channel SACDs.

Similar to the MLP method of DVD-Audio SACD also comes with a lossless compression algorithm to produce working. Before Completing the SACD Images the DSD audio format to DST ( Direct Stream Transfer) is converted. The compression rate - and thus the possible maximum playing time - is dependent on the audio material. Purely mathematically the maximum playing time is approximately 110 minutes ( single layer and hybrid disc ) or 200 minutes ( Double Layer). ( 2.8224 MHz, one bit per channel results in stereo 5.6 Mbit / s or 700 Kbytes / s, Single Layer ( SL) SACD 4.7 GB or Double Layer (DL ) SACD 8.5 GB = SL 110 minutes or DL ​​200 minutes ).

Variants

There are three types of Super Audio CDs:

  • Single Layer: contains a high-density ( HD ) layer and is playable only on SACD players.
  • Dual Layer: contains a second HD layer for extra recording time and is also playable only on SACD players.
  • Hybrid Layer: contains the HD a CD layer that is readable for normal CD player

In the hybrid disc technology, a CD and a DVD layer can be applied on the disc. The DVD ( SACD ) layer is seen from the laser before the CD layer; It is for light having a wavelength of 780 nm used for CD detection, transparent, and only reflected light having a wavelength of 650 nm is used for DVD- scan. It contains the audio data in the SACD quality. The underlying CD layer contains the audio data in the format of the audio CD (16 bit, 44.1 kHz) and can be read by standard CD players. Most SACDs are currently produced in this process.

Copy protection

Apart from the additional available in Hybrid SACD CD layer, like any audio CD is exactly easily played out and copied the contents of a high-resolution SACD are protected by a copy prior to the unwanted spread.

The copy protection method of the SACD is extremely effective. It consists of several layers of protection: Pit Signal Processing ( PSP ) is a digital, invisible watermark, which ensures the authenticity of the SACD. Here, in the pits (pits ), in which the data are coded, evaluated not only as the DVD, the length but also the width in which the watermark is encoded. PSP can only be created in the mastering process.

The lead-in area of an SACD is encrypted and can be decoded only by a hardware module in SACD players. In addition, the audio data is encoded by Content Scrambling and a portion of the required for decoding key can be found here in the SACD hardware. Both measures prevent that SACDs can be read on a standard DVD - ROM drives. Optionally can be inserted by PSP a visible watermark on the data page.

Furthermore, to pass the currently available players are resident on an SACD Content solely analog to the amp. The new multimedia interface HDMI understood since its version 1.2 but also on the digital dissemination of DSD data.

Market situation

Since 1999, the Super Audio Compact Disc (SACD ) is available on the market. The number of publications in the area of ​​pop and underground music is stagnant, there are hardly any new releases, and these are mainly older remastered albums. However, the SACD has performed well as a high quality audiophile recordings to date (2012 ) in the classical realm. There are monthly albums with mostly multi-channel mixdown new productions released as of labels such as BIS, CHANDOS, Hyperion, Haenssler Classic, MDG, EMI, Pentatone, Audiomax, Hamonia Mundi, Cybele, Tacet, Musicaphon, audite, Farao and others. Sony, Marantz, Pioneer, Yamaha, T A and Denon offer players for SACDs on, partly in the form of SACD players, partly as a BR player. Featured in each case is a universal player that can play all existing formats such as CD, SACD, DVD-Audio, DVD - Video, Blu -ray Disc.

The players of the first generation that were presented to the public in the spring of 1999, were not suitable with selling prices of around U.S. $ 5,000 for the mass market. It was not until a year later were able to acquire a player at tolerable prices audiophile interested in Japan. It was not until some years later, the SACD technology for the end user was available and attractively priced world.

In 2009, SACD Player from numerous brands for less than 200 €, available partially below 100 €. Meanwhile, there are numerous so-called universal player that dominate most formats, for example, SA- CD. On PC drives playing SACDs is not possible (except for the CD layer of a hybrid SACD). The first revision of the PlayStation 3 from Sony gave SACDs again, newer models no longer do so.

The number of available publications on SACD was in the market at about 40, the end of 2001 to over 500 in 2009, about 4500-5000 tracks were released on SACD, which is about five times as much as the number of the published DVD-Audio Title. Compared to the 1000 monthly CD releases this number for the mass market, however, is of little importance.

This is confirmed by the sales in the first half of 2004 that were in Germany at 100,000 copies. This corresponds to about 0.14 % of the total sales of all formats. In the United States, the SACD with 0.09% of the total sales in spite of a higher absolute number of units sold ( 300,000 ) during the same period at an even lower significance. (Source: IFPI, RIAA )

Future prospects

A breakthrough, as he was to determine the change from record to CD or from the VHS tape to DVD-Video, the two formats SACD and DVD-Audio did not succeed. The SACD continues to play in the classical realm, due to their high-resolution multi-channel capability is an essential and growing role. Today equip virtually all manufacturers have their BD- Multiplayer (2012 ) also with the functions of DVD-Audio and SACD.

On Blu- ray Disc have become the first pure audio tracks appeared ( from the label 2L from Norway), more such boards are being planned, such as the CD sound critic Neil Young and the classical label MDG. Very high but license claims of rights holders currently prevent widespread use of the Blu- ray Disc as a pure audio format.

Hearing tests

For stereo recordings no differences between a high-quality produced conventional CD and Super Audio CD are in objective hearing tests practically hear, so that the alleged due to the higher sampling rate and larger sampling depth better sound quality by Super Audio CDs over CDs could not be confirmed. However, SACDs offer the possibility of multi-channel recordings, which in a corresponding reproduction system, an audible difference in spatial sound reproduction can be achieved.

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