The recent high profile video disc battle between Blu-ray Disc and HD DVD is the second spat in the past decade to pitch Sony and Philips against the rest of the DVD Forum. But, in the case of Super Audio CD and DVD-Audio, there were no real winners. BILL FOSTER sifts through the wreckage...

When DVD was conceived in the mid-1990s the intention was that, unlike CD, a single platform would serve the video, music and computer markets. However, prevarication by the music industry over the specifications meant that only the DVD-Video and DVD-ROM formats were specified at the time of DVD’s 1996 launch.

A key criterion for a DVD-based audio format was support for 5.1 channels at the higher resolution of 96kHz/24-bit (compared with CD’s 44.1kHz/16-bit). Realising that this would require a total data rate of around 13Mbps, about 30% higher than DVD can deliver, a group of engineers under the banner of the Acoustic Renaissance for Audio (ARA) set about developing a lossless codec that would bring the rate below 10Mbps.

Meridian Lossless Packing (MLP) performed perfectly, passing all ‘golden ears’ tests, but there was another problem. With the DVD-Video specification already established, the intention was to use that platform for the audio-only format. What the ARA had not appreciated, however, was that the DVD-Video spec reserves more than 3Mbps for video, irrespective of whether there is any. This only leaves a little over 6Mbps for audio, not enough for a high quality 5.1 audio track, even with MLP.

Many would have given up at this point but audio engineers are a resolute bunch so in the late 1990s a completely new DVD-Audio format was devised, even though this would be incompatible with the growing installed based of DVD-Video and DVD-ROM players. The format offered a guaranteed minimum of 74 minutes (CD’s running time) at 96kHz/24-bit, with an option of stereo at an even higher sampling rate of 192kHz.

During the late stages of DVD-Audio’s development it suffered another setback when DVD-Video’s CSS encryption was hacked, sending the music industry into a panic. The result, after a further delay, was a new system, Content Protection for Pre-recorded Music (CPRM).

Another late addition to the spec added support for a Dolby Digital 5.1 version of the high resolution audio tracks to provide backwards compatibility with DVD-Video players. There is no copy protection on a DVD-Video audio track, but the record labels were persuaded that anyone wanting to ‘rip’ a copy of an album would more likely copy the CD than the lower resolution Dolby Digital track. What this still did not provide, though, was compatibility with the huge installed base of CD players.

The folks at Philips and Sony had recognised early on the issue of backwards compatibility with CD and had highlighted it to the DVD Forum. Whether this perceived need was borne out of a deep concern for consumers’ interests, or the threat to their revenue stream from the loss of CD royalties is unclear but, whatever their motivation, the two companies had been quietly working on their own audio format, Super Audio CD (SACD).

SACD was based on the same dual 0.6mm substrate as DVD, but otherwise employed intellectual property owned by Sony and Philips: the Direct Stream Digital audio codec (originally developed by Sony for archiving the library of analogue tapes it had inherited with the acquisition of Columbia Records) and Philips Direct Stream Transfer (DST) lossless coding technology.

To maintain backwards compatibility, an optional ‘hybrid’ version of the format contained an SACD and a CD on the same disc. An SACD player read the multi-channel data in the centre of the disc, whilst a regular CD player accessed the CD layer located in the usual place under the label.

SACD was launched in the Japanese market in 1999, but the limited amount of 5.1 material available at that time – and the lack of multi-channel DSD recording equipment – meant that the majority of these early releases were stereo only. This was not a major problem in Japan because the format was primarily targeted at stereo ‘audiophiles’, but it did create confusion in the US and Europe where SACD’s multi-channel capability was marketed alongside its superior audio quality.

This confusion was further compounded by the limited manufacturing capacity and high cost of making hybrid discs which meant that most of the early SACDs, whether stereo or multi-channel, were released without a CD layer.

DVD-Audio followed in 2000. Whilst a more consistent surround sound policy was adopted, it was greeted with a degree of indifference by the music buying public. Most early purchasers of discs were DVD-Video player owners with surround sound systems, who were happy to play the Dolby Digital tracks and watch the bonus video content that was included on most titles.

Ironically, both formats had to rely heavily on recordings from the 1970s for back catalogue releases. During the ’80s the record industry had begun to make extensive use of digital recording technology in order to promote the all-digital ‘DDD’ capabilities of CD. Digital recording in that era was limited to CD’s 44.1kHz/16-bit resolution, which did not do justice to DVD-Audio’s 96kHz/24-bit capability, or SACD’s even greater resolution, effectively eliminating an entire decade from these two formats’ catalogues.

Not that either format was receiving much support from retailers, many of whom didn’t know where to rack the discs. A display at a prestigious store in New York’s Times Square had SACDs, DVD-Audio discs and DTS CDs all mixed up in a rack marked ‘Other Formats’ – although few customers would have noticed as this display was right at the back of the basement level behind the pop star calendars!

Hardware support was also patchy. The SACD camp realised that the ultra high-end, US$3,000 audio-only players it sold in Japan would not attract many buyers in the US and Europe, so it launched more affordable products that included DVD-Video playback.

DVD-Audio players also supported DVD-Video, but, like SACD players, were more expensive due to the need to include additional electronics, including six high quality analogue audio outputs.

By 2000, DVD-Video had still to achieve wide scale household penetration and both parties therefore hoped that consumers would pay the little bit extra to buy a DVD-Audio or SACD player when making the transition from VHS to DVD-Video. A year of two earlier this might have been the case, but Chinese built DVD-Video players had started to appear and prices had already begun to fall significantly.

There was also the obvious question for consumers of which format to buy. As had happened early in the ’90s with DCC and MiniDisc (and was to happen again with BD and HD DVD), most titles were only available in one of the two formats.

The entrenched positions of Panasonic and Toshiba (DVD-Audio), and Sony and Philips (SACD), meant that buying hardware also required that consumers choose between the formats. Pioneer was the first to introduce a ‘universal’ player, and it enjoyed modest success, but Pioneer’s products are at the higher end of the price scale and were therefore not really in a position to significantly influence the market.

Once it became obvious that the general public would not willingly forsake CD for one of these new formats, the inevitable attempts began to influence the market through pricing.

By 2002/3, manufacturing of SACD hybrid discs had become more stable and yields were sufficient to guarantee supply. This provided the possibility for record labels to substitute a regular CD for an SACD hybrid, the only problem being the substantial additional cost. Despite this, several discs did appear in hybrid only, amidst allegations from the opposing camp that these were being subsidised.

What hybrid SACDs did achieve was to give the format a significant boost in the all-important numbers game. When Pink Floyd’s ‘Dark Side of the Moon’ reissue topped the US album charts the sales were attributed to SACD, despite the fact that most purchasers were probably unaware that another high-quality audio track even existed on the disc.

The significance of hybrid discs was not lost on the DVD-Audio camp, which had been working hard on a similar solution. But theirs was not such an easy task. Because DVD players also play CDs, when a disc is inserted they are programmed to check what type it is, and the majority check for a CD first. This meant that a DVD player would start to play the CD layer of a hybrid disc and ignore the high resolution or Dolby Digital audio on the DVD layer. (Being designed for the purpose from the outset, SACD players were all programmed to check for the high resolution layer first.)

As mentioned earlier, audio engineers do not give up easily. With the realisation that a single-sided hybrid was not going to work, attention was turned to a double-sided disc – one side CD, the other DVD. The problem here was the different distance between the data layer and the surface of the disc, which determines the thickness of the substrate: 1.2mm in the case of CD, 0.6mm for DVD. This would create a disc with an overall thickness of 1.8mm, outside the CD and DVD specifications, both of which specify a nominal thickness of 1.2mm but allow 0.3mm extra for manufacturing tolerance and label inks.

After some trial and error, a disc was developed that could be read reliably whilst at the same time meeting the required specification. Its two substrates were 0.9mm (for the CD) and 0.55 (for the DVD), making a total of 1.45mm. The DualDisc was born... and immediately ran into trouble when a German company claimed it infringed its DVDplus patents.

DualDisc was launched in 2004 with the first titles coming mainly from Warner Music. A relatively unknown US independent, 5.1 Entertainment, was also an enthusiastic supporter, releasing a significant number of titles in either full 5.1 or ‘faux surround’, where the surround image is synthesised from a stereo original.

The merged Sony BMG label also agreed to back DualDisc, but support for DVD-Audio was still one step too far for Sony. Consequently the DVD side of its releases had only a higher resolution version of the stereo CD Audio tracks along with bonus DVD-Video footage.

With the rising volume of illegal MP3 downloads, several record companies realised that audio quality was not a priority for most consumers and they too began to use DualDisc’s DVD side for bonus video material in an attempt to provide something that could not be downloaded free from the ‘Net. Other labels, perhaps still having concerns about DualDisc’s compatibility, simply bundled a CD and a regular DVD-Video in the same package.

Almost a decade after their launch, titles continue to appear on both SA-CD and DVD-Audio. The majority of those from the major labels are reissues of ‘classic’ albums from artists like Elton John, Genesis and the Alan Parsons Project, but increasingly it is the independent labels such as AIX Entertainment in the US, Linn Records in the UK and Sweden’s Opus3 that are keeping the flag flying for these two formats.

Even here, though, the migration to downloaded content is becoming evident. AIX’s subsidiary iTrax now offers a number of options for those who no longer want physical media, including a full bandwidth, 96kHz/24-bit resolution download. Try that with a dial-up connection!


Bill Foster spent the first 30 years of his working life in the sound recording industry, initially as a vinyl disc cutting engineer with Pye and CBS Records, and later as the co-owner of Tape One Studios, one of the world’s first digital audio mastering facilities. In 2000, Bill joined Understanding & Solutions (now Futuresource) as Senior Technology Consultant, a role he continues to fulfil whilst also working on a number of his own digital technology projects.

Story filed 10.09.08