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In recent years, developments in audio technologies, such as SACD and DVD-A among others, have opened up and inspired all kinds of exciting possibilities in audio design.
Super Audio CD (SACD) is a read-only optical audio disc format that can provide higher fidelity digital audio reproduction than the Red Book audio CD. Introduced in 1999, it was developed by Sony and Philips Electronics, the same companies that created the Compact Disc. SACD is in a format war with DVD-Audio, but neither format has managed to replace regular audio CDs.
Overview
SACD is a disc of identical physical dimensions to the compact disc but it uses a very different technology from CD and DVD-Audio to encode its audio data, a 1-bit delta-sigma modulation process known as Direct Stream Digital at the very high sampling rate of 2.8224 MHz. This is 64 times the sampling rate used in Compact Disc Digital Audio, which specifies 44.1 kHz at a resolution of 16-bit. Because the resolution of SACD is 16 times smaller than CDDA, the bitrate for a given channel is only 4 times as large.
There are three types of SACDs:
Hybrid: The most popular of the three types, hybrid discs include a “Red Book” layer compatible with most legacy Compact Disc players, dubbed the “CD layer,” and a 4.7 GB SACD layer, dubbed the “HD layer.” It is not uncommon for hybrid discs to carry the “Compact Disc Digital Audio” logo to show that the disc is CDDA-compliant.
Single-layer: Physically a DVD-5 DVD, a single-layer SACD includes a 4.7 GB HD layer with no CD layer.
Dual-layer: Physically a DVD-9 DVD, a dual-layer SACD includes two HD layers totalling 8.5 GB, with no CD layer. This type is rarely used. It enables nearly twice as much data to be stored, but eliminates CD player compatibility.
SACD authoring guidelines suggest that an SACD should always contain a 2-channel stereo mix[citation needed] though not all SACD have it (for example, in 2005 Sony Music Entertainment (Germany) GmbH released Charles Rosen’s performance of the Goldberg Variations as a hybrid SACD with 16-bit PCM and DSD 5.1 surround but no DSD stereo). They may optionally contain a surround mix — either 5.0 or 5.1 layout. Although the disc always stores all channels, the surround mix does not have to use them all, and some may be mute; for example the 2001 SACD release of Mike Oldfield’s Tubular Bells remains in the quadraphonic 4.0 mix made in 1975, and the RCA reissue of the 1957 Chicago Symphony Orchestra recording of Mussorgsky’s Pictures at an Exhibition marks the first time the original 3.0 (three track) recording is available in a consumer format. The correct designation for the surround part of an SACD is “multi-channel”, and usually has either the label “SACD Surround” or its own “Multi-Ch” logo on the back cover.
Integration
As of February 2008, there have been over 5,000 SACD releases, slightly more than 50% of which appear to be classical. Jazz and popular music albums, mainly remastered previous releases, are the next two most common genres released to date. [1][2]. Notable popular artists who have released some or all of their back catalog include Alice In Chains, Aerosmith, Björk, Black Sabbath, Boston, David Bowie, Carpenters, Depeche Mode, Bob Dylan, Peter Gabriel, Genesis, Billie Holiday, Elton John, The Moody Blues, The Rolling Stones, Eleanor McEvoy, Nine Inch Nails, Santana, and Barbra Streisand. Pink Floyd’s seminal album The Dark Side of the Moon (the 30th anniversary edition of 2003), The Who’s seminal album Tommy (the 34th anniversary edition of 2003), and Roxy Music’s Avalon (the 21st anniversary edition, 2003) were released on SACD to take advantage of the format’s multi-channel capability. All three were remixed in 5.1 surround, and released as Hybrid SACDs with a stereo mix on the standard CD layer.
Because most SACDs are issued in a hybrid format only, such as the remastered Rolling Stones and Bob Dylan albums released in 2002, music collectors may build and enjoy an SACD collection even if their only disc player is not designed to read the SACD’s higher fidelity DSD encoding. The ability to play SACD hybrid discs on all standard Red Book CD or DVD video players is considered a significant advantage of the SACD format over DVD-Audio. Today, there are many affordable “universal” multiformat players which play not only SACD but also competing formats DVD-Audio or DualDisc.
Despite relatively wide consumer availability to SACD players, however, high definition audio formats continue to attract few major record labels, which in the mid-2000s increased marketing of low-cost compressed audio formats. The main interest continues to be classical and older remastered albums rather than new releases. The record label Mobile Fidelity focuses on this type of remastering.
Disc reading
Objective lenses in conventional CD players have a longer working distance, or focal length, than lenses designed for SACD players. This means that when a hybrid SACD is placed into a conventional CD player, the laser beam passes the high-resolution layer and is reflected by the conventional layer at the standard 1.2 mm distance, and the high-density layer is out of focus. When the disc is placed into an SACD player, the laser is reflected by the high-resolution layer (at 600 µm distance) before it can reach the conventional layer. Conversely, if a conventional CD is placed into an SACD player, the laser will read the disc without difficulty since there is no high-resolution layer.
Playback hardware
Hybrid Super Audio CDs (which include both a Stereo CD and a Super Audio CD layer) can be played back on CD players. To hear the Super Audio CD Stereo, and on many discs the Super Audio CD Multichannel layer, requires a Super Audio CD player.
As would be expected, Sony and Philips – designers of the CD and SACD formats – have the most players on the market in many guises such as standalone players, combined DVD/SACD players, in-car players,[1] and Sony’s PlayStation 3 game console. (As of the 2.00 upgrade, PS3 is capable of SACD 5.1 playback via an optical cable. It achieves this by converting the audio to a 1.5 Mbit/s DTS format. The immediate revision after this removed the feature.[2])
The Sony SCD-1 is a well-known player which was introduced concurrently with the SACD format in 1999 for a price of approximately US$5,000.[3]. It weighs well over 26 kg (57 lb) and is often modified by its owners to improve the sound. The SCD-1, no longer produced, was introduced before multi-channel SACDs existed and only plays two channel SACDs or red-book CDs.
Many other electronics manufacturers, including mid-level vendors Denon/Marantz, Pioneer, Yamaha offer SACD playback capabilities throughout their product lines. None, however, has offered a portable SACD player capable of playing the high definition layer of an SACD. Most portable CD players will play the conventional CD layer of a Hybrid SACD.
SACD players are not permitted to digitally output an unencrypted stream of DSD. Players initially supported only analog output; later some proprietary digital interfaces such as Denon Link permitted encrypted transmission of DSD. There are now two standard digital connection methods capable of carrying DSD in encrypted form: i.Link and HDMI (version 1.2 or later, standardised in August 2005).
The older i.Link interface is generally found on older mid- to high-end equipment and some current top of the line units from the Japanese manufacturers. HDMI is more common, being the standard digital connection method for high-definition video+audio. Most new mid-level and higher 2007 model year and later A/V processors support the HDMI 1.2 specification’s DSD over HDMI feature. Most boutique manufacturers still do not support DSD. Some HDMI 1.1 spec DVD players convert DSD to LPCM and then pass it to an HDMI 1.1 spec or later processor. Lower end processors usually convert the DSD to LPCM, higher end ones usually convert it to LPCM for bass management or DSP but can also process it natively at the expense of DSP and bass management. Some new DVD players from Oppo Digital, Pioneer, Onkyo, etc. now support HDMI 1.2 or 1.3 and will pass DSD over HDMI as well as LPCM. Be aware that some players, for instance, Onkyo DV-SP504, will not support DSD or LPCM over HDMI without downscaling it to 48kHz. SACD or DVD-A will be played through anlaog outputs instead. The older i.Link interface has been dropped from all but high end A/V processors and DVD players.
Some players, such as the PlayStation 3 (not the 40GB version), do not output DSD over HDMI, but instead convert it to PCM.
DSD
SACD audio is stored in a format called Direct Stream Digital (DSD), which differs from the conventional PCM used by the compact disc or conventional computer audio systems.
DSD is 1-bit, has a sampling rate of 2.8224 MHz, and makes use of noise shaping quantization techniques in order to push 1-bit quantization noise up to inaudible ultrasonic frequencies. This gives the format a greater dynamic range and wider frequency response than the CD. Promotional materials about SACD supplied by Philips and Sony suggest that the system is capable of delivering a dynamic range of 120 dB from 20 Hz to 20 kHz and an extended frequency response up to 100 kHz, although most currently available players list an upper limit of 80–90 kHz.
The process of creating a DSD signal is conceptually similar to taking a 1-bit delta-sigma analog-to-digital (A/D) converter and removing the decimator which converts the 1-bit bitstream into multibit PCM. Instead, the 1-bit signal is recorded directly and in theory only requires a lowpass filter to reconstruct the original analog waveform. In reality it is a little more complex, and the analogy is incomplete in that 1-bit sigma-delta converters are these days rather unusual, one reason being that a 1-bit signal cannot be dithered properly: most modern sigma-delta converters are multibit.
Because of the nature of sigma-delta converters, one cannot make a direct comparison between DSD and PCM. An approximation is possible, though, and would place DSD in some aspects comparable to a PCM format that has a bit depth of 20 bits and a sampling frequency of 192 kHz. PCM sampled at 24 bits provides a (theoretical) additional 24 dB of dynamic range. Due to the effects of quantization noise, the usable bandwidth of the SACD format is approximately 100 kHz, which is similar to 192 kHz PCM.
Because it has been extremely difficult to carry out DSP operations (for example performing EQ, balance, panning and other changes in the digital domain) in a 1-bit environment, and because of the prevalence of studio equipment such as Pro Tools, which is solely PCM-based, the vast majority of SACDs — especially rock and contemporary music which relies on multitrack techniques — are in fact mixed in PCM (or mixed analog and recorded on PCM recorders) and then converted to DSD for SACD mastering.
To address some of these issues, a new studio format has been developed, usually referred to as “DSD-wide”, which retains standard DSD’s high sample rate but uses an 8-bit, rather than single-bit digital word length, but still relies heavily on the noise shaping principle. It becomes almost the same as PCM (it’s sometimes disparagingly referred to as “PCM-narrow") but has the added benefit of making DSP operations in the studio a great deal more practical. The main difference is that “DSD-wide” still retains 2.8224 MHz (64Fs) sampling frequency while the highest frequency in which PCM is being edited is 352.8 kHz (8Fs). The “DSD-wide” signal is down-converted to regular DSD for SACD mastering. As a result of this technique and other developments there are now a few digital audio workstations (DAWs) which operate, or can operate, in the DSD domain, notably Pyramix and some SADiE systems.
Note that high-resolution PCM (DVD-Audio, HD DVD and Blu-ray Disc) and DSD (SACD) may still differ in terms of fidelity at high-frequencies since DSD, owing to its high sampling frequency, does not show the ringing effects that PCM shows with certain types of signals when sharp reconstruction filters are employed[citation needed], but instead it shows constant high levels of noise at the same frequencies this ringing would show in 192 kHz PCM. On the other hand, DSD’s dynamic range decreases quickly at frequencies over 20 kHz due to the use of strong noise shaping techniques which push the noise out of the audio band resulting in a rising noise floor just above 20 kHz. PCM’s dynamic range, on the other hand, is the same at all frequencies. (Some high-end SACD players employ an optional low-pass filter set at 30 kHz for compatibility and safety reasons, suitable for situations where amplifiers or loudspeakers can’t deliver an undistorted output if noise above 30 kHz is present in the signal.)
DST
To reduce the space and bandwidth requirements of DSD (2.8 Mbit/s per channel), a lossless data compression method called Direct Stream Transfer (DST) is used — DST compression is compulsory for multi-channel regions and optional for stereo regions. This typically compresses by a factor of between two and three, allowing a disc to contain 80 minutes of both 2-channel and 5.1-channel sound.
Pit Signal Processing
SACD includes various copy protection measures of which the most prominent is Pit Signal Processing (PSP), a physical watermarking feature that contains a digital watermark modulated in the width of pits on the disc (data is stored in the pit length). The optical pickup must contain special circuitry to read the PSP watermark, which is then compared to information on the disc to make sure it’s legitimate. Because the majority of DVD players and all DVD-ROM drives use an optical pickup that lacks this specialized watermark detection circuitry they cannot read the data on the SACD layer of a protected SACD disc.[4]
On hybrid SACD discs, PSP is only applied to the SACD layer — not to the CD layer.
Comparing SACD and CD
Many people[who?] feel that even a moderately good system should reveal a significant difference between SACD and either CD or DVD-Audio. The late film composer Jerry Goldsmith, for example, fiercely backed SACD and several albums of his film scores and compositions are available as Hybrid Multichannel SACDs.
Increasingly, home audio playback systems are home cinema multichannel and this single feature may prove to be the most important when considering the differences between Compact Discs and the newer distribution formats. CDs are stereo and both SACD and DVD are multichannel-capable. In addition, SACDs can be authored to be both forward and backward compatible with existing CD players.
Few home audio systems can accurately reproduce sounds above 20 kHz, and most recording chains are designed around this limit. Modern popular music is often compressed during mastering to a small percentage of the maximum available dynamic range, and thus would not significantly benefit from the extended dynamic range available in SACD without remastering the audio for more dynamics. However, electronic and organ music offer a wide natural dynamic range, and audiophiles benefit from the lack of amplitude compression that an extended dynamic range affords.
Conversely, the properties of DSD and the authoring process tend to discourage the kind of extreme compression and unpleasant-sounding hard digital clipping often found on PCM recordings. Unlike CD, which sets the 0 dB level right at the theoretical PCM signal limit, and doesn’t take into account oversampling, SACD sets the 0 dB level at 6 dB below the theoretical full-scale DSD signal, and prohibits peaks above +3 dB. DSD processing is less amenable to simple clipping to meet these limits, forcing more care to be taken during mastering. The extra headroom also eases the job of DACs in playback equipment, which often suffer overload distortion when fed the full-scale PCM common on heavily-compressed CDs.[5][6] Thus, improved quality may result from simply preventing the kinds of poor mastering often found on PCM, rather than from any fundamental audible difference between DSD and PCM.[citation needed] PCM mastered several dB lower would also obtain the same benefit.
A 2007 article published in the Journal of the Audio Engineering Society reported the results of a study, which concluded that listeners could not hear the difference between a high-resolution two-channel recording and a CD-quality downsampling of the same recording except when “unpleasantly (often unbearably) loud."[7] The article concluded that many high-resolution releases sounded better than their CD counterparts, but attributes this to mastering differences.
Copy protection
SACD has several copy prevention features at the physical level which, for the moment, appear to make SACD discs impossible to copy without resorting to the analog hole, or ripping of the conventional 700MB layer on hybrid discs. These include physical pit modulation and 80 bit encryption of the audio data, with a key encoded on a special area of the disk that is only readable by a licensed SACD device. The HD layer of an SACD disc cannot be played back on computer CD/DVD drives, nor can SACDs be created except by the licensed disc replication facilities in Shizuoka and Salzburg.[8]
It is possible to capture the DSD digital audio signal after the decryption stage right before the digital to analog converters of an SACD player, but since there is no practical way for the public to make their own SACDs, this does not pose a major threat.
The failure of the format to gain any significant market share further reduces the incentive, whether commercial (e.g. Slysoft’s payware AnyDVD for DVDs and Hi-Def discs) or curiosity to create copying tools (e.g. “DVD” Jon’s DeCSS for DVDs). The quick defeat of protection methods used on HD DVD and Blu-ray Disc, when they accounted for only 4% of digital movie sales in 2007, shows that even a marginal market share can create demand for technologies that enable consumers to bypass the protection.
A number of new SACD players have encrypted IEEE 1394 (also called FireWire or i.Link) or HDMI digital outputs carrying DSD data, and it may be possible to get the raw DSD data from these links. The protection mechanism used is Digital Transmission Content Protection (DTCP), which can be used in “Copy Once” or “Copy Never” modes. It is unlikely, however, that the SACD license agreement rules permit anything but the “Copy Never” mode to be used.
There seems to be one solution for obtaining digital non-DRM output on SACD as well as DVD-A players. A Switzerland-based company is offering a modified output-board that taps into the digital datastream prior to D/A conversion as well as converting DSD to PCM that the S/PDIF port can transfer. [9]
See also
Audio format
Audio storage
DualDisc
DVD-Audio
Earlier attempts at higher fidelity that stayed within the CDDA standard: XRCD and HDCD.
[edit]References
^ “Sony Announces Three Super Audio CD Car Stereo Players”. HighFidelityReview.com. Retrieved on 2007-01-18.
^ “PS3SACD.com News, November 22, 2007”.
^ “The Sony SCD-1 SACD Player”. @udiophilia. Retrieved on 2006-05-18.
^ “Details of DVD-Audio and SACD”. DVDdemystified.com. Retrieved on 2007-07-12.
^ “Issues with 0dBFS+ Levels On Digital Audio Playback Systems”. Audioholics. Retrieved on 2007-05-10.
^ “Overload in Signal Conversion” (PDF). AES 23rd International Conference. Retrieved on 2007-05-10.
^ Meyer, E. Brad; David Moran (September 2007). “Audibility of a CD-Standard ADA Loop Inserted Into High-Resolution Audio Playback”. Journal of the Audio Engineering Society 55 (9).
^ “Sony Starts Hybrid Super Audio CD Production Facilities in Europe”. SA-CD.net (2003-01-22). Retrieved on 2007-07-12.
^ dvdupgrades.ch
[edit]External links
SA-CD site at Sony Music
SA-CD.net SA-CD Reference (Includes full list of available albums and comprehensive FAQ)
Multichannel SACD Rating: album guide for surround-sound lovers.
PS3SACD.com FAQ: a dedicated FAQ about SACD functionality on PlayStation3
Super Audio Compact Disc: A Technical Proposal (PDF), Sony.
The SA-CD explained
“Breaking the Sound Barrier: Mastering at 96 kHz and Beyond” (PDF) Audio Engineering Society Convention Paper 4357 on “HD” audio.
“A Native Stereo Editing System for Direct-Stream Digital” (PDF) Audio Engineering Society Convention Paper 4719 on the 1st DSD commercial editor.
“Why Direct Stream Digital is the best choice as a digital audio format” (PDF) Audio Engineering Society Convention Paper 5396.
“Why 1-Bit Sigma-Delta Conversion is Unsuitable for High-Quality Applications” (PDF) Audio Engineering Society Convention Paper 5395.
Janssen, E.; Reefman, D. “Super-audio CD: an introduction”. Signal Processing Magazine, IEEE/ Volume 20, Issue 4, July 2003 Page(s): 83 - 90
DVD-Audio
DVD-Audio (commonly abbreviated as DVD-A) is a digital format for delivering very high-fidelity audio content on a DVD. DVD-Audio is not intended to be a video delivery format and should not be confused with video DVDs containing concerts and music videos. The first discs entered the marketplace in 2000. Future occasional DVD-Audio releases are expected and/or have been announced. DVD-Audio is in a format war with Super Audio CD (SACD). Neither has gained a strong position in the marketplace. As media players that can play both DVD-Audio and SACD (and many other formats) are available, both are likely to co-exist.
Audio specifications
DVD-Audio offers many possible configurations of audio channels, ranging from single-channel mono to 5.1-channel surround sound, at various sampling frequencies and sample rates.[1] (The “.1” denotes a Low-frequency effects channel (LFE) for bass and/or special audio effects.)
Compared to the compact disc, the much higher capacity DVD format enables the inclusion of either:
Considerably more music (with respect to total running time and quantity of songs) or
Far higher audio quality, reflected by higher linear sampling rates and higher bit-per-sample resolution, and/or
Additional channels for spatial sound reproduction.
Audio on a DVD-Audio disc can be stored in many different bit-rate/sampling rate/channel combinations:
Different bit-rate/sampling rate/channel combinations can be used on a single disc. For instance, a DVD-Audio disc may contain a 96 kHz/24-bit 5.1-channel audio track as well as a 192 kHz/24-bit stereo audio track. Also, the channels of a track can be split into two groups stored at different resolutions. For example, the front speakers could be 96/24, while the surrounds are 48/20.
Audio is stored on the disc in Linear PCM format, which is either uncompressed or losslessly compressed with Meridian Lossless Packing. The maximum permissible total bitrate is 9.6 Megabits per second. Channel/resolution combinations that would exceed this need to be compressed. In uncompressed modes, it is possible to get up to 96/16 or 48/24 in 5.1, and 192/24 in stereo. To store 5.1 tracks in 88.2/20, 88.2/24, 96/20 or 96/24 MLP encoding is mandatory.
The LFE channel is actually full range, and can be recorded at the same resolution as the other channels. This permits it to be used instead as an extra main channel, for example as a “height” speaker above the listening position; this has been done on some releases. Such usage is non-standard, and will often require special set-up by the end user.
If no native stereo audio exists on the disc, the DVD-Audio player may be able to downmix the 5.1-channel audio to two-channel stereo audio if the listener does not have a surround sound setup (provided that the coefficients were set in the stream at authoring). Downmixing can only be done to two-channel stereo, not to other configurations, such as 4.0 quad. DVD-Audio may also feature menus, text subtitles, still images and video, plus in high end authoring systems it is also possible to link directly into a Video_TS folder that might contain video tracks, as well as PCM stereo and other “bonus” features..
Player compatibility
With the introduction of the DVD-Audio format, some kind of backward compatibility with existing DVD-Video players was desired, although not required. To address this, most DVD-Audio discs contain, a Dolby Digital 5.1-channel audio track on the disc[2] (which can be downmixed to two channels for listeners with no surround sound setup). Some discs also include a native Dolby Digital 2.0 stereo, and even a DTS 96/24 5.1-channel, audio track.[3]
Because the DVD-Audio format is a member of the DVD family, a single disc can have multiple layers and even two sides that contain media. A common configuration includes a “DVD-Video” zone on a DVD-Audio formatted single sided disc. The high-resolution, multichannel audio losslessly encoded using MLP is only playable on DVD-Audio hardware but the DVD-Video zone, which can contain Dolby or DTS 5.1 mixes and even video makes the disc compatible with all DVD players. Other configurations include double layer DVDs (DVD-9) and two-sided discs (DVD-10, DVD-14 or DVD-18). Some labels are releasing DVD titles that are formatted as DVD-Audio on one side and DVD-Video on the other, the DualDisc being one such example.
There are some software players that support the playback of DVD-Audio discs, including WinDVD and PowerDVD.
[4]ELS Surround is one of the few vehicle audio systems which can play DVD-A
Preamplifier/Surround Processor interface
In order to play DVD-Audio, a preamplifier or surround controller with six analog inputs was originally required.[5] Whereas DVD-Video audio formats such as Dolby Digital and DTS can be sent via the player’s digital output to a receiver for conversion to analog form and distribution to speakers, DVD-Audio cannot be delivered via unencrypted digital audio link at sample rates higher than 48 kHz (i.e., ordinary DVD-Video quality) due to concerns about digital copying.[5]
However encrypted digital formats have now been approved by the DVD Forum, the first of which was Meridian Audio’s MHR (Meridian High Resolution). The High Definition Multimedia Interface (HDMI 1.1) also allows encrypted digital audio to be carried up to DVD-Audio specification (6 × 24-bit/96 kHz channels or 2 × 24-bit/192 kHz channels). The six channels of audio information can thus be sent to the amplifier by several different methods:
The 6 audio channels can be decrypted and extracted in the player and sent to the amplifier along 6 standard analog cables.
The 6 audio channels can be decrypted and then re-encrypted into an HDMI or IEEE-1394 (Firewire) signal and sent to the amplifier, which will then decrypt the digital signal and then extract the 6 channels of audio. HDMI and IEEE-1394 encryption are different from the DVD-A encryption and were designed as a general standard for a high quality digital interface. The amplifier has to be equipped with a valid decryption key or it won’t play the disk.
The third option is via the S/PDIF (or TOSLINK) digital interface. However, because of concerns over unauthorized copying, DVD-A players are required to handle this digital interface in one of the following ways:
Turn such an interface off completely. This option is preferred by the music publishers.
Downconvert the audio to a 2-channel 16-bit/48 kHz PCM signal. The music publishers are not enthusiastic about this because it permits the production of a CD-quality copy, something they still expect to sell, besides DVD-A.
Downconvert the audio to 2 channels, but keeping the original sample size and bit rate if the producer sets a flag on the DVD-A disc telling the player to do so.
A final option is to modify the player, capturing the high resolution digital signals before they are fed to internal D/A converters and convert it to S/PDIF, giving full range digital (but only stereo) sound. There exist already do-it-yourself solutions for some players. There also exists an option to equip a DVD-A player with multiple S/PDIF outputs, for full resolution multichannel digital output. See: Six channel S/P-DIF output board.
Sound quality
From a purely technical standpoint, the audio resolution of a DVD-Audio disc can be substantially higher than standard red book CD audio. DVD-Audio supports bit depths up to 24-bit and sample rates up to 192 kHz, while CD audio is 16-bit, 44.1 kHz. In both cases, the source recording may have been made at a much higher bit and sample rate, and down-converted for commercial release.
It is uncertain whether average listeners can hear the difference between DVD-Audio and CD-Audio, and many consumers do not regard any supposed quality improvements offered as sufficient reason to justify purchasing new playback equipment and repurchasing albums in higher-resolution formats. Many DVD-Audio releases are older, standard definition audio recordings that have been remixed in 5.1 and upsampled to DVD-Audio’s higher resolution. However, the fidelity of the upsampled audio will be limited by the source material quality and may not exceed the quality of existing CD releases of the same albums. When new recordings are made using high-resolution PCM encoding, a substantial difference in fidelity can be achieved.[citation needed]
Three of the major music labels, Universal Music, EMI and Warner Bros. Records and several smaller audiophile labels (such as AIX Records and DTS Entertainment) have released or are continuing to release albums on DVD-Audio, but the number is minimal compared to standard CDs. New high-definition titles have been released in standard DVD-Video format (which can contain 2-channel Linear PCM audio data ranging from 48 kHz/16-bit to 96 kHz/24-bit), “HDAD”, which includes a DVD-Video format recording on one side and DVD-Audio on the other, CD/DVD packages, which can include the album on both CD and DVD-Audio, or DualDisc, which can contain DVD-Audio content on the DVD side. In addition, some titles that were initially released as a standalone DVD-Audio disc, such as The Grateful Dead’s American Beauty and R.E.M.’s Automatic for the People, were re-released as a CD/DVD package or as a DualDisc.
Copy protection
DVD-Audio discs may optionally employ a copy protection mechanism called Content Protection for Prerecorded Media (CPPM).[6] CPPM, managed by the 4C Entity, prevents users from extracting audio to computers and portable media players.
Because DVD-Video’s content-scrambling system (CSS) was quickly broken, DVD-Audio’s developers sought a better method of blocking unauthorized duplications. They developed CPPM, which uses a media key block (MKB) to authenticate DVD-Audio players. In order to decrypt the audio, players must obtain a media key from the MKB, which also is encrypted. The player must use its own unique key to decrypt the MKB. If a DVD-Audio player’s decryption key is compromised, that key can be rendered useless for decrypting future DVD-Audio discs. DVD-Audio discs can also utilize digital watermarking technology developed by the Verance Corporation, typically embedded into the audio once every thirty seconds. If a DVD-Audio player encounters a watermark on a disc without a valid MKB, it will halt playback.[7] The 4C Entity also developed a similar specification, Content Protection for Recordable Media (CPRM), which is used on Secure Digital cards.
DVD-Audio’s copy protection was overcome in 2005[7] by tools which allow data to be decrypted or converted to 6 channel .WAV files without going through lossy digital-to-analog conversion. Previously that conversion had required expensive equipment to retain all 6 channels of audio rather than having it downmixed to stereo. In the digital method, the decryption is done by a commercial software player which has been patched to allow access to the unprotected audio.
In 2007 the encryption scheme was overcome with a tool called dvdcpxm. In 12 February 2008 a program called DVD-Audio Explorer 2008 was released, containing aforementioned libdvdcpxm coupled with an open source MLP decoder.[8]
Like DVD-Video decryption, such tools may be illegal to use in the United States under the controversial Digital Millennium Copyright Act. While the Recording Industry Association of America has been successful in keeping these tools off websites, they are still distributed on P2P file sharing networks and newsgroups,[9] Additionally, in 2007 the widely-used commercial software DVDFab Platinum added DVD-Audio decryption, allowing users to backup a full DVD-A image to ISO.[10]
DVD-Audio authoring software
Normal DVD(Video) authoring software usually does not support DVD-Audio creation, so there is some special software:
[edit]Macintosh
Sonic Solutions DVD Creator AV – The first DVD-Audio authoring solution available. A spin off of the popular high end DVD Video authoring package. It allows DVD-Audio authoring at the command line level only. Still widely used but no longer sold or supported by Sonic Solutions.
Sonic Studio SonicStudio HD – Macintosh based tool used for High Density audio mastering and to prepare audio for DVD-A authoring in One Click DVD.
Sonic Studio [1]
Sonic OneClick DVD – Converts prepared Sonic Studio EDLs into binary MLP files to be used in the authoring tool. Also generates scriptFile information to be added to DVD Creator AV projects.
DVD audio Tools: console application dvda-author (version 08.07), see below.
[edit]Windows
Sonic Solutions DVD-Audio Creator
Cirlinca DVD-AUDIO Solo
Minnetonka Audio DiscWelder Bronze, Steel and Chrome II (with SurCode MLP)
Steinberg WaveLab Steinberg
DigiOn Audio 2 DigiOn
Gear Pro Mastering Edition Gear Pro Mastering Edition
DVD audio tools package (see below).
[edit]Linux
A project called DVD audio Tools provides free/open source DVD-Audio authoring tools for Linux and other *nix platforms (FreeBSD, OpenSolaris,...).
Windows (console application) binaries are also available. DVD-Audio/Video discs (aka Hybrid or Universal DVDs) are also supported.
See also
Meridian Lossless Packing
[edit]References
^ “Understanding DVD-Audio” (PDF). Sonic Solutions. Retrieved on 2007-07-12.
^ “SACD & DVD-Audio: Ultra-High-Resolution Music”. Crutchfield Advisor. Retrieved on 2007-07-12.
^ “What is DVD-Audio?”. 5dot1.com. Retrieved on 2007-07-12.
^ www.elssurround.com
^ a b “DVD-Audio Tutorial”. TimeForDVD.com (2002-06-05). Retrieved on 2007-07-12.
^ Labriola, Don (2003-08-25). “Digital Content Protection, Part II”. ExtremeTech. Retrieved on 2007-07-12.
^ a b Robinson, Stuart M (2005-06-07). “DVD-Audio Copy Protection Defeated via WinDVD Software Hack”. HighFidelityReview.com. Retrieved on 2007-07-12.
^ “DVD-Audio ripper”. Retrieved on 2008-04-09.
^ “DVD-Audio’s CPPM Circumvented”. Slashdot.org (2005-07-06). Retrieved on 2007-07-12.
^ “DVDFab updated to support DVD-Audio/CPPM”. Retrieved on 2008-04-15.
[edit]External links
The 4C Entity LLC – Licensors of the Content Protection for Prerecorded Media (CPPM) specification.
Articles in the Audio Designers category
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