Getting the best sound around

March 28, 2011
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A disruptive technology that will affect both lovers of packaged media and converters to online digital delivery is poised to make a very big noise. At the IP&TV World event in London, one of the pioneers of digital audio gave a demonstration of the music-on-the-move MP3 format on an Apple iPhone. When connected to a conventional home cinema system, the stereo turned into glorious 5.1 surround sound with very little loss of fidelity.

By the end of last year there were close to 100 million home cinema households around the world, most of them with stand-alone 5.1 audio systems designed to sound their best when playing DVD or Blu-ray discs. By Q4 2011, retailers will sell a further 10 million units including an increased proportion of integrated systems with a Blu-ray drive.

The 1977 release of “Star Wars” heralded the arrival of Dolby Stereo in the cinema and the technology was transformational: almost anyone with two ears could hear the difference. By 1993, surround sound helped secure the success of “Jurassic Park” using Digital Theatre Sound (DTS) and multi-channel audio went on to win audiences around the world. Because the 5.1 track occupied unused space on the film print, distributors had no concerns about multiple inventory and cinema operators could upgrade at their own pace.

Since the launch of the DVD format in 1997, many film titles feature the Dolby Digital or DTS surround soundtrack, sometimes both. Although most households rely on tiny stereo speakers built in to their large and expensive flat screens, the surround soundtrack remains on the disc. The stamp of quality conferred by the Dolby or DTS logo printed on the sleeve is a marketing tool that sells both packaged media and home cinema systems. Until recently, online entertainment had to make do with stereo.

In January 2011, the research organisation Parks and Associates asked consumers what factors affect their decision to rent or buy internet video from a site such as iTunes or Amazon. Top of the list was “picture quality and resolution” (72%), followed closely by “ability to play the video on a TV” (69%), “price” (69%) and “sound quality” (68%). More than half of those responding cited “surround sound audio” (54%) as important, which indicates a demand that is greater than the current supply.

To deliver quality surround sound is a problem for anyone involved in the creation, management and distribution of digital content. The issues of version control, synchronisation and rights management bedevil the production process whenever there are two or more streams to consider. Then there is the need to edit each soundtrack to suit national cultural concerns, such as the removal of words such as “fuck” in the US version of “The King’s Speech”.

The limited bandwidth available in any broadband connection is a further constraint. In many cases, the minimum data rate of 1.5 Mbps needed for 5.1 audio exceeds the total allocation for sound and vision in an online steam.

The problems don’t end on arrival in the home. Handling two or more completely separate streams in a set-top box or connected TV is out of the question, particularly if the consumer has to make a choice between several alternatives. A single audio stream is the only practical answer, with automatic switching aligned to the capabilities of the home system.

The DTS demonstration highlighted its major advantage over previous technologies: the 5.1 sound is indistinguishable from a stereo signal from the moment of encoding in the production process to decoding in a domestic sound system. At every point in the delivery chain, including editing and monitoring, it is simply stereo sound.

When DTS bought Neural Audio for $7.5 million in mid-2009, few people realised the significance of the acquisition, and its fruits only now become clear. The original 5.1 surround sound stream is encoded as DTS Neural, at any bitrate suitable for stereo music and with any digital audio format including MP3. Once encoded, no further processing is required and the data can be copied, broadcast, distributed and played like any other stereo sound.

The DTS silicon is built-in to recent home cinema systems and is to be incorporated in IPTV set top boxes and connected TVs. The decoder detects the incoming DTS Neural signal in the online data and converts it into a conventional 5.1 stream at 1.5 Mbps, for connection through an HDMI cable.

The really clever part of the process is the incorporation of an encoder in the consumer box, which re-encodes the signal as the S/PDIF data that every legacy home cinema system can understand. From then on, the surround sound goes to the individual speakers as usual and recreates the original multi-channel track. DTS Neural can perform this trick from an analogue input as well, hence the success of the London demonstration of an iPhone plugged into the system.

Consumers do not replace their home cinema equipment as frequently as other high-tech consumer electronics products, partly because of the relatively high original investment and partly due to the stability of the DVD and Blu-ray technology, unchanged since launch. As a result, only around 10% of systems in the home have the HDMI connector needed to deliver the full range of audio features. By including the S/PDIF output, DTS Neural enfranchises 100% of the installed base of home cinema users.

Thanks to DTS Neural, the online delivery of home entertainment just took a big step towards satisfying the needs of the audiophiles with expensive speaker systems. They might represent only 10% of the market but the evidence is that they spend more than the average on music and video, although it is unlikely that they use their iPhone as its source. 

For the moment.