21 июля 2005, 00:01

Battle of DVD formats: will friendship win?

What is the outcome of the battle between DVD "plus" and "minus"? The manufacturers have squeezed whatever possible from their formats, and the market has been saturated with universal drives that support both standards. I can foretell the same future for both HD-DVD with Blu-ray. But before that we are in for a spectacular battle of a large number of eminent companies. So, what is it all about, and what is the current state of affairs?

I am sure wars among formats of optical media will never cease. Primarily because it's just the implacable struggle among two-three clans of manufacturers that moves the technical progress. Competition not only refreshes brains but affects the price. We all witnessed how slow the CD is and how quickly the DVD became accessible to public.

What is the outcome of the battle between DVD "plus" and "minus"? The manufacturers have squeezed whatever possible from their formats, and the market has been saturated with universal drives that support both standards.

I can foretell the same future for both HD-DVD with Blu-ray. But before that we are in for a spectacular battle of a large number of eminent companies. So, what is it all about, and what is the current state of affairs?

How it all began

DVD-R and DVD+R were still conquering the mass market when the development of new more capacious formats put forward by manufacturers was in full sway. Already in 1996, Phillips, Toshiba, and Sony demonstrated to the world the first prototypes of the devices that used blue-violet laser to write data on a disk. But developers were facing a lot of problems related to excessive heating of the drive and search for the suitable layer, etc.

On 19 February 2002, nine companies (Hitachi, LG Electronics, Matsushita Electric, Pioneer, Philips, Samsung, Sharp, Sony, and Thomson Multimedia) announced development of specifications on the format of new-generation optical disks dubbed «Blu-ray Disc». The name suggest the main peculiarity of the new format - use of a blue-violet laser. Originally, 27 GB capacity on a 12-cm disk was announced.

Already in August, information on the Blu-ray format became known to the public. In September, competitors - Toshiba and NEC - responded with the Advanced Optical Disc (AOD) format. In October, AOSRC put forward its own standard - HD-DVD.

Prototypes of BD- and AOD- drives started appearing on various shows, e.g. Ceatec in Japan in October 2002 and at Consumer Electronics Show (CES 2003) in January 2003.

First prototype of the future HD-DVD

First prototype of the future HD-DVD

First prototype of Blu-ray at Ceatec Show 2002

First prototype of Blu-ray at Ceatec Show 2002

Finally, on 13 February 2003 the Blu-ray Disc Association started licensing the new format which meant an official emergence of BDA on the market of optical drives and a say-so for a start of producing commercial products on the base of the Blu-ray.

Only one issue was left to be solved: which format will the DVD Forum (a consortium of companies in charge of standardization and certification of optical media) choose?

In November 2003, absolutely unexpectedly for many the HD-DVD specification that incorporated Toshiba's and NEC's AOD was selected as the working format for next-generation DVD-ROM disks. The superiority of votes in favor of HD-DVD was minor - 8 versus 6.

The emergence of HD-DVD specification was very hard. While the number of Blu-ray supporters was going up and companies were announcing new prototypes of drives and media, DVD Forum was trying to win unanimity in its ranks. The HD-DVD 1.0 specification was approved on only 10 June 2004.

Technical traits of competitor solutions

The new-generation optical media have only common disk size and blue-violet 405 nm wavelength laser (not blue, as many believe). Transition to a shorter wavelength laser allows placing data on a disk more densely fitting up to 27 GB data per single data layer.


HD-DVD drive

HD-DVD drive

HD-DVD disk

HD-DVD disk

Perhaps the decisive argument in favor of adopting this standard by DVD Forum was its legacy and continuity to the existing DVD-disks. To transit to the manufacture of new produce, a minimum upgrade of existing lines is required. Even the integrated circuits in the drives can be left as before: data read/correction algorithms used are the same - it suffices to replace the optical head only.

Optical disks are of the same size and layer structure. The recording layer is in the middle under the protection of a 0.6 mm layer of plastic.

As compared to DVD, the distance between the tracks and the pit sizes have gone down almost twice as much, which allowed to increase the disk capacity from 4.7 to 15 GB. By now, a 30 GB dual-layer specification has been adopted. Besides, Memory Tech and Toshiba are planning to create 3-layered disks of 45 GB capacity.


Blu-ray drive

Blu-ray drive

Blu-ray disk

Blu-ray disk

This format is radically different from the DVD. It uses entirely new new data reading and processing algorithms which allow attaining greater flexibility of the media physical structure. For example, the pit length may be 0.138, 0.149, or 0.160 mk.

The recording layer on the disk is merely 0.1 mm off the surface. Therefore, distortions of the laser beam and response time are reduced. All that allows essentially reducing the pit sizes and distances between tracks as compared to the regular DVD. In the upshot: a BD disk houses 23.3, 25, or 27 GB of data.

The 46.6 and 50 GB BD disk specification has been approved. Toshiba has released a 4-layered 100 GB disk.

One of the bottlenecks of Blu-ray is the too small gap between the recording layer and the surface – 0.1 mm versus 0.6 mm in DVD and HD-DVD. Originally, the only method of protection against damages in BD disks was a cartridge. But then, a number of companies (e.g., TDK) developed special protective coatings able to sustain scratches, clogging with dust from cartridges.

This photo is the best demonstration of differences among the three generations of optical media.

Pit sizes on CD, DVD, and BD

Pit sizes on CD, DVD, and BD

The difference between Blu-ray and HD-DVD standards is easy to see if we look at their major specifications, but it is hard to give preference to any of them:

Capacity of a standard (ROM) single-layer disk, GB0,684,723,3/2515
Capacity of a standard (ROM) dual-layer disk, GBNo8,546,6/5030
Capacity of a rewritable (RW) single-layer disk, GB0,684,723,3/25/2720
Capacity of a rewritable (RW) dual-layer disk, GBNoNo46,6/50/5432
Capacity of a single-layered recordable (R) disk, GB0,684,723,3/25/2715
Capacity of a dual-layered recordable (R) disk, GBNo8,546,6/50/54No
Maximum capacity of existing prototypes of multilayered disks, GB1,48,510045
Laser wavelength, nm780650405405
Ray power on reading, mW--0,350,5
Protective layer, mm1,20,60,10,6
Pit size, nm830410160 (23.3 GB) 149 (25 GB) 138 (27 GB)204 (15 GB)
Distance between tracks, nm1600740320400
Data transmission rate, Mbit/s-11,136 (1x) 72 (2x) 54 (video BD-ROM)36.5 (1x)
Support for JavaNoNoAvailableNo
Supported codecs-MPEG2MPEG2 MPEG4 AVC VC-1MPEG2 MPEG4 AVC VC-1
Data protection systems-CSS AESAACS

The latter three items look most weird and mysterious thus opening another large topic.

Who needs HD-DVD and BD-ROM

New formats emerge on the market only when there is a need for them. DVD-disks have gained such a wide occurrence due to the two reasons:
1) they house video films of quality much better than on CD;
2) the size of program distribution packages, databases and games started exceeding the capacity of CDs.

The capacity of a dual-layer DVD-ROM for now is more than enough for whatever needs of the common user.

But there are users who are not common. Those who buy a DLP TV-set or a plasma panel that supports 1080i resolution and are going to record the most interesting TV programs on optical disks. The HDTV stream which in the not distant future hopefully will be used in Russia to broadcast TV programs requires much more space than DVD can provide. For example, a dual-layer 50 GB BD-ROM disk houses no more than 2.5 hours of high-quality video (in the standard quality, it is 13 hours).

For more dense data packing, the two new formats, except the standard MPEG2 codec, support a few more: MPEG4 AVC (also known as H.264) and Microsoft VC-1. The thing is, when encoding 1080i video data to the MPEG2 format image artifacts caused by compression become visible, and the stream rate rises to 20-25 Mbit/s. The MPEG 4 AVC may reduce the stream by 3-4 times without loss in quality.

Blu-ray and HD-DVD provide simultaneous reading of data from disk and recording new information. Besides, the Blu-ray will support Java-applications, which will allow increasing the level of video disk interactivity. For example, on startup such a video disk will be able connecting to the manufacturer's web site and downloading the subtitles in the required language.

In developing the standards, the issue of content copy protection has been given an important focus. As is known, the CSS protection used in DVD was successfully broken, which allowed copying video films without obstacles (isn't it the reason why the format has become so popular, and single-recording disks have proved to be of highest sales?). In new-generation optical disks, more advanced methods will be used.

Blu-ray uses 128-bit Advanced Encryption Standard (AES) in which the encryption key changes in every 6 Kbytes of data. In the end, decryption of one key gives the intruder access to 6 Kbytes of data. As you understand, it is impossible to break such protection (for now).

HD-DVD uses an improved version of the CSS method - Advanced Access Content System (AACS). Plus, the second degree of protection - Self Protecting Digital Content (SPDC). For each drive, AACS generates its own 128-bit Device Key (DK). Each disk has its own Media Key Block  (MKB) which can operate only with a certain DK combination. If a combination of DK is suspected of any illegal actions, the MKB is refreshed, and the respective DK combination is put into a black list – the disk contents won't be played back.

This approach allows finding flaws which may bring a lot of trouble to the innocent user, but anyway the protection is aggressively reliable. Perhaps this will help film studios protect against piracy and earn a lot of money.

Yes, that is so, indeed. Currently, Blu-ray and HD-DVD formats are aimed primarily at the film industry. It's just the film industry that sets pace and pay the money. The users have nothing to do but watch the repertoire of recently released BD and HDVD films and decide which drive to buy.

Battlefield chronicles

It is curious to keep track of the battle between the two formats, especially because the passions are acute indeed nowadays. That is related to the first attempts to launch a mass production of disks and drives.

Why not? The Hollywood film industry seems to have decided upon the formats. Warner Brothers and New Line Cinema have signed exclusively for HD-DVD, Walt Disney Co., Sony Pictures, and MGM – for Blu-ray. Universal Studios and Paramount Pictures, albeit non-exclusively, but are among the followers of HD-DVD, while Disney and 20th Century Fox – to the followers of Blu-ray.

Films recorded on new optical media will not keep us waiting for long: the first films recorded on HD-DVD disks by Universal are expected to arrive by Christmas-2005, whereas Paramount Home Entertainment will release a catalog of its films in this format early in 2006.

Basically, the war of formats is going on peacefully enough. The followers of opposing camps sometimes meet and speak out for a unified standard of optical media, being aware that this may save a lot of nerves to the consumers and a lot of money to the manufacturers (see «Blu-ray versus HD-DVD: new steps to reconciliation»). But, as is already evident, no compromise can be found because none of the parties is willing to give up its own developments.

Being aware of that, some companies like Microsoft and Sanyo, are taking neutral grounds and are ready to deal with both.

There has appeared information that at designer laboratories of a number of microelectronics giants a work on creating hybrid optical heads and integrated circuits which support both formats is under way. Of course, the hybrid may prove to be complicated and expensive, but we know that mass production is able working miracles reducing the total price of the produce down to acceptable figures.

For now, we are still waiting for the first established production lines for Blu-ray and HD-DVD. HD-DVD disks are to appear on sales in spring 2006 simultaneously with suitable drives. Blu-ray drives and disks will start their massive assault onto the market at approximately the same time.

At the start, Blu-ray drives are expected to cost much higher than HD-DVD but the prices will become equal with time.

What will be after Blu-ray and HD-DVD?

Now that new standards are just about to emerge on the market, there appears information on the development of new formats of incredible price. Most often, it takes quite a long time even for prototypes to emerge because patent applications are under processing.

Take, for instance, the project by Colossal Storage Corporation related to creating 3.5" Atomic Holographic Disks of 10 Terabytes capacity! It sounds like a fairy tale, but it may still remain a fairy tale.

Colossal drive and disk in the artist's eyes

Colossal drive and disk in the artist's eyes

Another interesting project has been suggested by HVD Alliance including CMC Magnetics, Fuji Photo Film, and a number of other companies. That is development of Holographic Versatile Discs (HVD). The capacity of such a disk is within 100 to 1000 Gigabytes. The main secret is about using a million of lasers at a time, not one! The reading speed at that may be as high as 1 Gbit/s.

Holographic Versatile Disc

Holographic Versatile Disc

Quite similar to the already created formats is the development by New Medium Enterprises which is about to present the Versatile Multilayer Disc (VMD) able housing 20 GB and uses a regular red laser. That is simply a 4-layered disk. The first drives for this format are to appear on sales this year already, but most likely they won't go further than the Asian region since they are purely a transition.

Quite recently, Iomega has patented the Articulated Optical-Digital Versatile Disc (AO-DVD) technology related to further reduction in the pit size and emergence of short-wavelength lasers. As a result, to store data nano-structures will be used – portions of the disk space whose size is smaller than the laser's wavelength! Theoretically, such a disk will be able housing up to 800 GB of data.

Digital Multilayer Disc

Digital Multilayer Disc

Finally, D Data is developing the Digital Multilayer Disc (DMD) for the red laser and which supports up to 6 layers, having capacity of up to 15 GB. Its operation principle - the active layer starts illuminating when exposed to a focused laser beam (fluorescence effect), whereas in the normal state it remains absolutely transparent. That is why the number of layers can be increased to six and even more - what matters is to focus the laser on the required layer. The idea is nice, and the manufacturer's website presents a roadmap up to 2007 when blue laser and 400 GB discs are to come. But for now, nothing is heard about these discs, and they will certainly not find support among the large film corporations.

So, what forecast to make? For now, the efforts of competitors in the field of optical storage are equal, and in the nearest future they will be involved in the improvement of two major formats - HD-DVD and Blu-ray. Multilayered disks will appear, data transmission rates will rise, prices will go down. Then, there will come the time of new technologies.

With time, the number of interesting projects will only rise. Part of them will become extinct, but two-three will stand out which will come as a replacement to Blu-ray and HD-DVD in order to continue the battle of formats. Not for the money sake or for domination. But for the sake of further progress.

Автор: Aleksandr Radaev