The definitive guide to high-definition surround sound

What with all the attention given to high-definition and 3D in 2010, it’d be easy to underestimate the role of great sound in the film experience. But think about it: what was it that made the shark attack in Jaws so scary? Why did the opening scene of Star Wars leave such an indelible mark on most contemporary viewers? And why, even now, does the opening scene of Saving Private Ryan possess the power to shock so completely?

Simply put, the answer is great sound. Spielberg knew that sharks were silent, stealthy killers: it took John Williams’ powerfully affecting score to heighten the terror of each attack. George Lucas was just as profoundly aware of the need for great sound: he needed it to hide the flaws in his 1970s-vintage special effects. Once the thundering engines of a Star Destroyer have screamed over your head, you’ll pay less attention to the fact that, quite obviously, it’s all being done with models. And then there’s Saving Private Ryan, that paragon of surround sound savagery, as realistic a multichannel masterpiece as any in movie history: here, the sonic intent was to both convince and terrify, and did it ever work.

So great sound counts. In fact, according to Randy Thom, one of Hollywood’s most acclaimed sound designers, it counts so much that “If you look closely at and listen to a dozen or so movies you consider to be great, you’ll realise how important sound is in many if not most of them”. Or to put it another way, while watching a great movie in stereo through bandwidth-limited television speakers has little impact on your ability to understand dialogue or follow the plot, it’s still a long way short of the complete entertainment experience the director originally intended you to have.

All the more reason to buy a Blu-ray player and an appropriate multichannel amplifier, receiver or processor: the combination of these two (or three) components, used in harness with a good-quality surround speaker system, will get you closer than ever to the original sound of the master audio tracks created by the world’s best sound designers.

Older disc formats such as DVD are comparatively careless with the precious cargo they bear: in essence, when we talk about data compression for DVD sound, what we really mean is data ‘reduction’, because elements of the original source audio are permanently discarded during the disc-encoding process. With Blu-ray’s uncompressed and lossless audio technologies, that doesn’t happen, so the end result can be sonically identical to the original.

Identical? Really? Unbelievably, the answer is yes. For any film, sounds are first recorded and engineered as uncompressed 24-bit/48kHz PCM audio (far better than CD quality, which is 16-bit/44.1kHz PCM): this is then mixed in the studio to create an original master. After that, the finished soundtrack is usually heavily compressed to create final versions of the movie for distribution on film or, subsequently, for domestic use. This is very similar to the way MP3 works on a CD-quality piece of music: indeed, Dolby Digital, the most commonly used compression system found on DVD discs, stores audio at transfer rates very similar to a good MP3 file (384 to 448kbps, or kilobits per second).

This compromise is enforced by the technical difficulties involved in cramming surround sound on to a film reel, on to a limited-capacity data disc or, most recently, on to a DVD. DVD can only offer between 4.7 and 9.4GB of storage space for the completed movie presentation, and its video is packaged using less-efficient MPEG2 compression, which requires more space per second of video information than newer, more efficient systems. That, plus the need to accommodate numerous extra features and, in discs destined for the European market, additional soundtrack options in other languages, has meant that on many DVD releases, audio has frequently come a poor third to its two space-hungry rivals.

But Blu-ray has up to 50GB of storage capacity and often uses newer and much more efficient video compression systems compared to DVD, so there’s no need
to cram in data to fit the space available. In fact, there’s so much space on a 50GB disc that it can even accommodate a studio-quality 7.1 channel 24-bit/48kHz PCM soundtrack, if needed: the only inhibiting factors are the duration of the film, the extent of the extras included and the willingness of each studio to make the effort. As a guide, two hours of 7.1 channel, uncompressed 24/48 PCM audio would need 8.3GB of space, or less than 20 percent of the space on a 50GB Blu-ray.

That said, not all Blu-ray discs afford dual-layer 50GB capacity: many films are released as single-layer 25GB discs. Even here, it¹s possible to fit multiple channels of uncompressed PCM audio onto a 25GB disc ­ but at the same time, to do so obviously takes up a relatively larger proportion of the available capacity.

So, to create room for extras, soundtrack options and video, most studios have adopted one of two approaches. Some have preferred to down-convert the 24-bit PCM original into a 16-bit/48kHz version. This still sounds very good, because even down-converted, uncompressed PCM will deliver more dynamic range and detail than a Dolby Digital soundtrack. Two hours of 16/48 7.1-channel PCM occupies 5.5GB of disc space ­ a useful capacity saving.

However, rather than opting for a lower-quality version of PCM, an alternative is to use a ‘lossless’ packaging system, either DTS-HD Master Audio or Dolby TrueHD. These work rather like zip files in home computing: they repackage the 24-bit/48kHz PCM master (or whichever quality of master is available) into less space, rather than down-converting it. All that’s required is some way of ‘unzipping’ the data file to recover the original PCM audio, which can be done inside your Blu-ray player, or, depending on the type and quality of kit you own, inside most new surround amplifiers, receivers and processors.

Using this lossless approach, a 24/48 7.1-channel PCM soundtrack packaged using Dolby TrueHD requires 4.2GB of space, meaning it occupies about half the disc space of the same soundtrack stored as uncompressed data. Clearly, that makes lossless packaging attractive for studios releasing single-layer 25GB Blu-ray discs, and even on dual-layer 50GB discs, it’s frequently used for films with long running times.

Whichever type of lossless packaging system is used, the salient point is this: the sounds you eventually hear will be bit-for-bit identical to the original studio master, and should also sound better than a down-converted 16-bit/48kHz PCM alternative.

Which lossless system sounds best? It’s frequently asked, but it’s also fundamentally irrelevant. For starters, very few discs are encoded with both forms of lossless audio, (because studios have no vested interest in doing so), so any direct comparisons between the two systems are very difficult to carry out. But just as importantly, each form of encoding system uses variable bit rates and different data algorithms, so while DTS-HD Master Audio has a nominally superior maximum audio bitrate (24.5Mbps, as against 18Mbps for Dolby TrueHD) in practice the two technologies are far harder to separate.

Whatever the theory, the key point is this: with Blu-ray, film soundtracks can sound far more dynamic and spacious than their DVD equivalents. In fact, your favourite films can sound as good as the original studio masters, which is a giant leap forward in quality for home cinema. All you need is the appropriate electronics and loudspeaker to make the most of them.

HIGH-DEFINITION AUDIO FORMATS

Uncompressed:

PCM
Pulse-code modulation, sometimes referred to as Linear PCM or LPCM, is broadly used on CD, in computer audio and on Blu-ray. In the latter context, bit depths of 16, 20 and 24-bits are used, with the latter quality, sampled at 48kHz, being the most commonly employed ‘master’ standard in film production. Every Blu-ray player must support PCM as standard, although not every disc includes a standard PCM soundtrack for the reasons outlined above. In essence, its disadvantage is solely that it demands considerable space on a disc.

Lossless:

Dolby TrueHD

One of the two key lossless audio formats (referred to as ‘codecs’) on Blu-ray. It’s an optional rather than mandatory part of the audio specification for Blu-ray, but is widely supported just the same. Supports bit-depth of up to 24 bits and  sampling rates up to 96kHz at up to eight channels (arranged as 7.1, typically), with higher sampling rates (192kHz) available for soundtracks with fewer channels of audio. The maximum encoded bit-rate is 18Mbps, although in practice most discs use much less than that.

DTS-HD Master Audio
The other key lossless audio codec on Blu-ray. It’s also optional, but it’s more widely supported (so far) than Dolby TrueHD. Supports bit-depth of up to 24 bits and sampling rates up to 96kHz for up to eight channels (arranged as 7.1, typically), with higher sampling rates (192kHz) available for soundtracks with fewer channels of audio. The maximum encoded bit-rate is 24.5Mbps, although in practice most discs use much less than that.

Lossy:

Dolby Digital Plus

Rarely used on Blu-ray, this compressed audio system offers significantly better quality than standard Dolby Digital, with the potential for data rates as high as 6Mbps, although typical usages are much lower that that (around 1.5Mbps, maximum). Up to 7.1 channels of discrete audio can be included, at up to 24-bits, although more frequently 16-bit audio is used.

DTS-HD High resolution
Another relative rarity on Blu-ray, DTS-HD HR is broadly similar to Dolby Digital Plus in that it supports up to 6Mbps datastreams, up to 7.1 channels of audio and up to 24-bit data.

TOP FIVE AUDIO SCENES ON FILM:

The Dark Knight

Sound Designer Richard King won the Academy Award for Sound Editing in 2009
for his work on Chris Nolan’s second Batman film ­ hear it on Blu-ray, and you’ll immediately understand why. Presented in Dolby TrueHD, this is a masterful demonstration of deft effects placement intermixed with formidable dynamics. As with all the best soundtracks, it’s not afraid to use silence as a dramatic counterpoint to volume, either.

Saving Private Ryan

Still one of the most celebrated surround soundtracks in film history, Gary Rydstrom’s Academy Award-winning masterpiece is as intense as modern home
cinema sound gets. Deftly intermixing furious power with astonishing attention to period detail, the DTS-HD Master Audio presentation is thrilling and terrifying in equal measure.

Sherlock Holmes


Chris Munro’s work on the DTS-HD Master Audio presentation to Holmes disproves the myth that all the best home cinema experiences rely on action sequences to deliver thrills: while it¹s blessed with considerable dynamics, the soundtrack here works just as well at modest volumes and with apparently quieter, more subtle effects: it¹s especially effective at wrapping surround information around you.

Up

Want a home cinema thrill your kids can enjoy, too? Try this: its DTS-HD MasterAudio soundtrack features 6.1 audio for additional rear-speaker spaciousness, and this adds considerable extra scale to the film¹s grander scenes. There’s all the low-frequency thunder you could want, too ­especially during the film’s standout thunderstorm sequence!

Avatar

Yes, the film that everyone went to see at the cinema is now the film that everyone¹s going to buy on Blu-ray, but with good reason: this THX-mastered disc features not a single extra, allowing almost all its 50GB capacity to be given over to delivering the best-possible sound and vision. It¹s a purist approach, but one that delivers outstanding results in DTS-HD Master Audio.

19 Comments

  • J.B. says:

    It amazes me how so many of these articles are reluctant to point out the key differences between Dolby & DTS. I have always found Dolby soundtracks to be less dynamic & accurate than DTS soundtracks. The presence of the surround channels in DTS soundtracks dwarfs those of Dolby. I am glad that DTS is dominating the lossless marktet & I hope that the trend continues.

  • Andrew Brennan says:

    Many thanks for this most informative piece.

  • Pierre-André says:

    Since many years I use “CDBurnerXP” to burn my audio CD from FLAC 16/44,1; 24/48 and also 24/96. CDBuner XP is a FREEWARE to do the essential, not like a “gaz plant” like the most popular soft did for money 50€ at least.
    I hope that this comment will complet well the “Definitive Guide of 24B FLAC”

  • Ian Shepherd says:

    “Which lossless system sounds best ?”

    If any lossless audio system sounds different from the source, it’s broken – by definition.

    So they should all sound the same…

  • Allan says:

    FLAC should have been the standard, however that would end DTS and Dobly sharing a monopoly in taxing the film industry. I am glad that the studios have been putting the full version of the soundtrack on the disks, and I love it; my neighbors not so much. Rather ironic that the record labels have fallen behind in sound quality, since that’s the only thing they offer. Seems the movie industry caters to the extreme and record companies to the masses. The nonstandard hdmi standard is a major dissapointment. Sadly the computer industry has infected the hometheater industry. This relates back to codecs, I hope they stop with the current codecs, because in the computer world, everyone has their own not ‘superior’ codec that dosn’t work without user ‘tech support’. My only complaint with bluray is the price, I would buy substantially more disks if they were 20 versus 30. Her’s an idea for the music industry, releasing good quality concert blurays, the one that I have so far is great, sounds better than the cd. Infact it’s time for Itunes and record labels to catch up and deliver 24bit 48k downloads without drm in FLAC. The ability to have instant gratification without the future regrets of poor quality and artificial monopolization would be huge(hint apple, audiophiles spend lots of money). Apple could dominate the audiophile world be going high qualtiy downloads on a quality device. Put a hardrive in it though, shouldn’t have to run a 300 watt gaiming computer to play music in another room.

  • Jeppe Ovesen says:

    Concerning the nonstandard HDMI, I agree with the poster above.. It feels more like computer equipment than HI-FI.. With the 1,3a/1,3b/1,4a and so on, makes me feel my AMP goes obsolete as fast as my PC… It feels like a money sink, and less like an investment as it used to be.. I mean seriously.. It is a data transfer cable.. They have been making them since the 60′s.. Why aint it possible to make a cable that does what it needs to do, without releasing NEW “versions” every year..? I am happy that i do not give a hoot about the sale gimmick that is 3D..

    But a great article, and beeing a movie fan and a home cinema nerd im glad to see that movie producers goes to such great lengths to ensure a thrilling soundtrack quality. I agree with the movies mentioned above. Personally i would like to recommend:

    Public Enemies, District 9 and Cloverfield.. To name a few.

  • Eric Nino says:

    Movies with great sound editing besides the ones mention above, which I own in blu-ray.

    Hurt Locker.
    Thin Red Line.
    Iron Man 2
    Kick Ass

  • Steve says:

    I bought a Yamaha DSP A-1, their flagship 7.1 DTS surround receiver back in the late 90s with hope of DTS really flooding he market with titles or music….where did DTS go? My Yamaha sat with a few DTS recordings – Goucho Steeley Dan, Miles Davis and the few others I could find. Now Im far beyond the Yamaha and big box stores offerings and have been a 2-channel guy with a Parasound, B&W, Bel Canto system. With Classe now on the doorstep of revealing their 1.4 HDMI repeater I may venter back into the HT venue but then would have to also buy new power amps for rears, subs, etc…. Is it worth it and will 3D be all they say it will. Ive seen some of the 3D trailers – astounding visually. how will it all come together I wonder, like DTS?

  • Andysor says:

    Lossless, by definition, is just that. The only reason for a studio to use one over the other is space efficiency and encoding time.

    Apparently DTS Master HD has been better in those regards leading to its popularity. Dolby are claiming they have improved on theirs and are attempting to fight back. In any case, it makes no difference to the consumer.

    There are only 2 ways manufacturers can entice the consumer to replace their equipment regularly: products breaking or becoming obsolete. Electronics have become quite long lasting leaving the latter as the main driving force. I often wonder what the next innovation will be in home theatre as few people have a need (or opportunity) for more than 5.1 channels, lossless audio is acoustically transparent and 1080P is above our eye resolution limits for anything but a ridiculously large screen at a short distance.

    3D and other gimmicks are the only option.

  • HiFiAficionado says:

    “But Blu-ray has up to 50GB of storage capacity and often uses newer and much more efficient video compression systems compared to DVD, so there’s no need to cram in data to fit the space available.”

    Compared to DVD, Blu-ray discs store a picture that is approximately 2 MP in resolution. I thought that DVDs were only about a quarter of that. Is Blu-ray’s video compression system that much more effective? I thought that it produced higher-quality results, rather than simply trying to compress more.

    It would seem that Blu-ray’s 50 GB of storage versus DVD’s 9 GB is a big factor that provides the space for better quality video compression schemes, as well as uncompressed and/or lossless audio.

  • HiFiAficionado says:

    Is Blu-ray sound really better in all aspects than that which is provided by the soundtracks on DVDs? I’ve read elsewhere that some people believe that Blu-ray soundtracks have less low-frequency content than does the same release on DVD. Is that true? Whether or not it is true, what might be the explanation for such an opinion? Having a lossless audio stream is onething, but if some information has been deliberately not included then it isn’t as lossless as initially supposed.

    Is multi-channel surround sound (e.g. 7.1, 5.1) all that wonderful? Wouldn’t it be preferable to have a high quality pair of speakers with a subwoofer, rather spreading that same speaker budget across 5 or even 7 loudspeakers of lesser quality? Unless the room is suited fo 5.1 or 7.1 reproduction, it would seem that the use of such systems is a victory for marketing over quality.

  • Jason Russell says:

    It seems more and more blu ray discs are encoded in DTS-MA. However, to get the best from this format, you need full range (and identical to the front) real channel speaker to get the best from it.

    I much prefer DTS-MA over DTD, just sounds much more dynamic and alive…

    I’m lucky in that I have a Yamaha RXV3900, two pairs of B&W CM7′s and Two CMC as my speakers, and combined with my REL R205, have a beautiful, well balanced sound, not only for home cinema, but also for music.

    Just find it annoying that some early blu ray discs do not automagically select the HD soundtrack :(

  • Bob Smith says:

    When a blu-ray disc has either DTS HD or DD HD sound tracks and you select PCM on your Blu-ray player (BDP LX-91) will this be the best possible sound option?

  • Steve L says:

    Andysor when speaking about the difference between DTS vs, Dolby says that “it makes no difference to the consumer.” I feel that is rediculous. I’m no sound quality technician but the quality of DTS over Dolby is like night and day. I am just a lowly consumer but, I know good sound when I hear it!

  • John Bastberg says:

    I would like to comment on my speakers. Since I’ve got the two last M1 speakers to complete my 7.1 theater system I’ in heaven. The clarity and crispness in sound and a very tight bass completes me experience and joy when I put on a movie in my blu-ray player. It’s very diffucult for my wife to get in contact with me, ’cause I feel I’m not on this earth. I’ve had many different speaker systems; but allways gone back to B&W. So you soundwizzards, keep up the good work and enrich the world with your magic.
    John Bastberg, Copenhagen Denmark

  • Stuart says:

    Interesting to see the views above, many of which I agree with. I have a basic 683 surround system hanging off a NAD T785 with an Oppo BDP-83 SE . Must admit that I find the DTS-HD eats DD-HD. Just seems richer to myself and with less emphsisi on the Center. Might be a setting somewhere beceuse they do not sund the same.

  • Jerry says:

    @HiFiAficionado… Yes…yes it is! I don’t care how good your fronts are. You can’t even compare it to a dedicated center channel for dialog and rears for effects. 2.1 vs 5.1/7.1 are not even in the same ballpark.

  • Scott says:

    I agree when J.B. says Dts is much stronger than Dolby. The only films I have heard that are on par with a dts master audio mix are The Dark Knight and Batman Begins. Every other recording I have heard is more muffled and less spacious. On DVD the difference increases exponentially in Dts favor. Even going back to Laserdisc which yes I still own.

  • Paul Schumann says:

    This letter was sent to Kobus Bosch Managing Director Bowers & Wilkens South Africa,
    Morning Kobus,

    If you remember a few months ago I sent you all a thank you letter for the fantastic system that I bought through Robert your dealer in Cape Town. (Set of B&W CM9′s, set of 683′s for rear’s, set of 685′s for rear surrounds, CM center 2, ASW 10 CM subwoofer all driven by a Marantz SR7007 and a UD5007)

    Sometimes things happen to one in their life that at the moment looks all dark, gloomy and yet one does at times find some joy which brings about a small feeling of contentment, this story of mine is one of those occasions..

    It has always been since I was stationed in Walvis Bay, during my national service in 1984 when I first heard a set of Bowers & Wilkens speakers, to one day own my own set. Unfortunately life had an uncanny way of denying that dream of becoming a reality until 6 months ago.

    I got married to my wife 6 and a half years ago, and tragedy struck 11 months later when she was paralyzed from the neck down from a car accident. The driver was a 3 times reckless & negligent offender which we after the accident found this out.
    6 years of painful court battles and a television broadcast on Carte Blanche left us with hope that she might get a settlement so as to rebuild our life after losing everything through this tragedy. As life is sometimes cruel this was not to be.

    I was left with the very difficult task of looking after my wife single handed since the accident, medical aid ran dry after it topped R1,6 million. Still one keeps the faith and puts one step forward at a time to maintain some sort of composure and more importantly to keep showing a sense of positiveness towards my wife.

    Ellen is still paralyzed from the neck down and recently contracted Sugar Diabetes along with massive water retention from failing Nymph Glands.

    I was fortunate fro a few years of hard work and some good contracts to be able to afford the system which I bought from you via Robert.

    My wife being the way she is I am virtually house bound as well, she cannot be left alone. When I received the system it was still all in boxes, my excitement was difficult to contain until, a few days later when Robert came to install the system.

    Kobus, that system and quality of sound brought such joy to my wife that she actually started improving slightly through the power of quality sound and good music. Thanks to you all!!

    Up until a month ago all was well until a phone call from our lawyer. The phone call was to inform us that a new law was introduced and through this new law our entire case had collapsed. We we all heartbroken and this had dire consequences on my wife’s health, She suddenly spiraled downwards and contracted Sugar Diabetes with complications, to top it all I had to suddenly sell with a very heart, my entire new system. A dream come true system that had brought, for the brief time joy into our hearts and helped with my wife’s illness.
    I need not say as to how much my heart was broken especially that I am at home coping with running a business and the mammoth task of looking after my wife 24/7.
    I eventually sold the system which I paid R81000.00 for at R63000.00.
    The money had to go to urgent medical expenses as my wife was gravely ill.

    Being heartbroken at the loss of the one thing that helped me cope with the entire situation, the system was extremely difficult. I had managed to put aside a small R10 000.00 which I knew could impossibly replace what I had. After painstaikinly searching the ads I was lost as to how to replace with a smaller system that still would sound good.
    That is when I stumbled upon the A7 on your web site. Knowing that Bower’s & Wilken’s are the best and above all the rest in my and many others opinions, I ordered the unit without even listening to it beforehand.
    Once it arrived a few days later I was almost heart broken again when I, upon opening the box, saw how small the unit was.
    Reluctantly, I set it up and got it working through I Tunes on my lap top.
    I was awe struck, WELL DONE BOWER’S AND WILKEN’S and all at HFX. That little unit put out a sound quality that left one and many others simply speechless!

    It may not be anything as good as my “valley of broken dreams” former Bower’s & Wilken’s setup but it helped soothe the wounds a bit.
    My wife and I still miss the other system terribly but the A7 helps to keep one positive in the hope that maybe one day again I could afford through a miracle the former system.

    Thanks to all at HFX and Bower’s and Wilkens Worldwide and know that quality does count and can mend many a wound.
    Thank you all.
    Ellen and Paul
    +27735336155

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