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Appeared on: Friday, August 08, 2003
Hybrid SACD/DVD


1. Page 1

Hybrid SACD/DVD (Part 1 of 3)

By Stefan Schreiber

The present situation

The current situation is well-known and unsatisfactory: the simultaneous market-introduction of two competing standards for high-resolution audio and surround-sound (DVD-Audio and SACD) is leading to big problems in the audio industry - and additionally, to frustration for audiophiles and "consumers" who are, in some cases, unable to reproduce on their audio-players a disc available for the competing standard.

As even DVD-Video is apt to distribute audio-recordings (and, of course, music-video), it could be said that there do exist three potential "CD successor" formats at the same time.

While the SACD standard allows a hybrid disc-form containing a CD-layer compatible with CD-players, DVD-Audio discs are often mastered as DVD-AudioV, containing audio recordings for normal DVD-players (Video), often in stereo (for example, PCM-96kHz), or in compressed surround-formats (Dolby Digital, DTS). Of course, DVD-AudioV discs can include music-video and further "extras".

As a "general" solution for the ongoing format-war between SACD and DVD-formats, it is often demanded that all new and advanced audio reproducers were "hybrid players", supporting both formats. These hybrid players should support the "DSD" (kind of high-resolution bitstream) modulation of SACD, and PCM in all quality levels of DVD-Audio (up to 192kHz, 24Bit). Although this sounds very convincing, it won't happen, in my opinion.

It is quite possible to equip hybrid players with chips supporting both formats, and also to design combined DACs supporting both DSD- and PCM-modulations. However, good reproducers will need different analogue paths after the conversions. The price of audio reproducers is mainly a consequence of good analogue components and DACs, not of ICs supporting two or three formats "digitally".

Some of the announcements made by Chinese manufacturers about the possibility to offer DVD-players with DVD-Audio- and SACD-support, for maybe $100, have to be considered from a critical point of view. The problem is not to support a format "digitally" and to reproduce it "somehow"; you have to do it well, especially in the case of audio. Otherwise, you wouldn't have to replace the "Compact Disc" at all, which already can sound quite well, but certainly not "perfect forever".

It is difficult to design a DVD-player with "good" audio-quality. It is needed experience and know-how for this task. Up to now, hybrid SACD/DVD players are usually better for ONE of the two formats, for example, because they convert DSD to PCM (up to 192kH) and vice-versa. This conversion isn't completely "without loss", and will result in "PCM with less dynamic bandwidth", or in "DSD with less temporal resolution".

It is revealing that hardly any hybrid SACD/DVD-Audio player can be considered to be a CD-player of "reference-class", which, considering sometimes high prices, is quite amazing, because you can very well "upsample" PCM in 44.1kHz/16Bit both to PCM in 96kHz (or 192kHz) AND to DSD, all in the digital domain. Expensive CD-players are quite often doing exactly this...

The current (and maybe future) low market-share of such hybrid players has very understandable reasons. The DVD-player market is extremely price-competitive. If a DVD-player is also a hybrid DVD-A/SACD player, it would be too costly and in a too high price-category for most customers. Audiophiles would consider buying such hybrid players, but they will be normally too expensive to be competitive in the mass-market. A DVD-player supporting both formats won't be a best-selling model, for price-reasons. Today, and probably also in future, obviously not every DVD-player is even supporting only ONE of the two high-resolution formats.


2. Page 2

Hybrid SACD/DVD (Part 2 of 3)

By Stefan Schreiber

The new proposal

However, there might be a "soft" solution for the ongoing format-war: the introduction of hybrid two-sided discs, with one SACD-layer on one side (at least) and music in the formats DVD-Video and/or DVD-Audio on the second side (maybe the same). This solution works easily, because in the most basic case, a SACD half-disc is glued to a DVD half-disc. The consequence is a normal optical disc (1.2mm), containing "correct" layers for both DVD- and SACD-players. SACD- and DVD-Audio-players will see their respective layers, with the right specifications. Obviously, there isn't any problem concerning "compatibility".

This format (SACD/DVD) has at least two main applications. Firstly, it is probably the only "practical" possibility to include music video into the SACD-standard.

Music video has a broad range of uses and applications (video-clips for pop/rock music, live-concerts, musicals, ballet, operas...). In my opinion music video on videodiscs has a great future ahead, especially combined with high-resolution tracks and surround-sound. Philips and Sony might have thought to extend the SACD-standard for video (using the "Extra Data Area"); however, a new standard SACD-Video wouldn't have any chance beside the (mighty and official) DVD-Video.

Secondly, every record-label would have the possibility to release a record on SACD/DVD-Audio (V), offering both formats in one medium. Of course, this is an absolute future-proof solution for the customer, who knows that at least one of both standards will survive. In this case, a further advantage for the record-label would be that they will not have to consider parallel editions for both DVD-Audio and SACD formats any more, which has happened in some cases and seems to be completely unnecessary now.

Both hybrid SACD/DVD-Video and SACD/DVD-Audio discs can be produced without big problems as "DVD 10" (double-sided DVD) on all existing DVD production lines. A more complete SACD/DVD-Audio/Video disc, containing music and maybe video in three formats, will be manufactured (normally) in a "DVD-14" process. Of course, (at least) one of the used "masters"/matrices for the injection moulding process has to be "cut" as SACD-master by a special Laser Beam Recorder (LBR).

A DVD-14 (I prefer to call it more precisely a "DVD-14", because of the included non-standard SACD-layer) goes through a more complicated process of manufacturing, usually requiring the so-called "Surface Transfer Process" from Time Warner (to manufacture a two-layered DVD half-disc). However, this is a commercially used production process, and not "science fiction". For example, the DVD-Audio editions of AIX Records are usually two-sided discs, three-layered, requiring exactly this kind of DVD-14 manufacturing process.

A single-sided SACD/DVD (read from the same side, one layer SACD, the second layer DVD) can't work. The first problem starts with the fact that both SACD- and DVD-players would expect "their" respective "Lead-in" on Layer 0. DVD- and SACD- Lead-Ins are not compatible and, additionally, a SACD Lead-In would be encrypted. There are different file-systems, and so on.


3. Page 3

Hybrid SACD/DVD (Part 3 of 3)

By Stefan Schreiber

The benefits of the new format

In my opinion, the music market for media should be split into two separate segments. Firstly, I think CDs should and could be offered cheaper, which could also help to fight increasing pirating and illegal copies. The more expensive segment would be to offer recordings in a higher quality, and maybe with a lot of additional features (music-video, surround-sound, information about composers, musicians and specific recording "histories", multimedia, "interactivity"...). My proposals combine all the "versatile" DVD-possibilities with the elegance, directness and transparency of DSD-recording, the modulation used in the SACD standard. Secondly, DVD-Video, DVD-Audio and SACD can be offered combined on ONE disc, effectively unifying the market of the three CD-successor formats.

Every record label can decide independently in which format(s) their records should be published. I think the hybrid SACD/DVD proposals are helpful to both industry and customers. The music industry should consider this new hybrid disc - which is compatible with DVD in its various forms and SACD - not only for their own interest, but also for the best interest of THEIR customers. (I think somebody is still needed to listen to music...). And perhaps, it could also offer a solution to put an end or at least "ease" an otherwise fruitless and costly format-war, which, in the worst-case scenario, could lead to the complete failure of both formats at some point. In any case, a clear winner in the "format-war" between DVD-Audio and SACD is not yet to be seen. This time it is not a case like "VHS versus Beta". I think it is worse! Because it doesn't look like any one of the competitors will vanish. Both offer advantages and disadvantages, and both are backed by big electronic companies AND record labels.

If only the recording-industry (and audio industry in general) could concentrate on other things rather than in a fight between some incompatible standards, and think in categories such as "high-resolution music", "surround-sound", "music-video", "bonus-material", a combined DVD/SACD format seems immediately viable and logical.

Editor's Note: The new hybrid format is patent-pending.

 

Some Remarks

1. Rumours about an extension of the SACD-standards ("SACD II"), which seem to confirm that a "SACD with video" is planned, underline the significance of the SACD/DVD proposals, at least a potential solution for this aim.

" SACD II" (only rumoured, not "official") might be realized in two ways:

a) SACD + "SACD-video" in the SACD "Extra Data Area". Such discs would be realized probably as Dual Layer SACDs ("DVD-9"-version). In any case, it is not possible to have a surround-version AND music video on a "hybrid SACD" with CD-layer. There is not enough space for it on ONE HD-layer.

b) DVD-Video + "new audio standard" (based on DSD). This "idea" could be compatible to DVD-Video, but would break "backward-compatibility" to SACD (I). It would be equivalent to DVD-Audio/Video, which exists already now and doesn't need new players.

The first variant is compatible to SACD, but introduces a proprietary video-standard. The second proposal breaks SACD into two segments, and not any person I have asked thinks it will or "should" happen.

A SACD/DVD-Video hybrid is a "SACD" and a "DVD-Video", combining the advantages of a) and b). It works with existing players, and it is obviously a "100% compatible" hybrid disc, respective to the used standards. It is hard to see where SACD II could offer (functionally) "more" than a SACD/DVD-V.

Not having seen any "specifications" of SACD II (which isn't announced officially, but rumoured, again!), I can't say anything about aspects like copy protection or DRM-management of SACD II. However, Super Audio CD is an extremely well-protected format already now, whereas "advantages" of DRM will remain "abstract" or even questionable for customers.

2. Renewed efforts to introduce a DVD-A/CD will be reviewed if something "real" is announced, which hasn't been the case. Even if the inventor has participated in the discussion about DVD-A/CD hybrids with industry insiders, it is not directly related to my own proposals here.

However, the new proposal contains as special variant also an SACD/CD/DVD hybrid. You can manufacture such a disc, if you glue to the back-side of a "hybrid SACD" (that is, an SACD/CD) a DVD half-disc, which itself can have one or two layers.

This disc-form is (usually) thicker than a "standard DVD", or CD. Usually the thickness will be 1.7mm, similar to the already known DVD-plus (DVD+CD). Both disc-forms are facing similar compatibility-problems, therefore. To be fair, the DVD-plus is a commercially available format, even if the discs are always out of some specifications, also thinner forms of DVD-plus! However, they work mostly, especially as "DVD".

To me, it looks very unlikely that we will see a DVD-A/CD as "single inventory disc", that means, as a DVD-Audio which can be sold "as CD".

3. Last, but not least, I would like to put a link to a German Internet-article on hybrid SACD/DVD, done by Mr. Ulrich v. Loehneysen and myself. (The last picture visualizes in a highly understandable way both forms of "hybrid SACD" discs! It's not possible to explain it easier, I think.)

Many thanks, to Ulrich v. Loehneysen, and to my colleague Joe Coronado for editorial advice.



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