Why 2-disc releases?

[Rumpelstiltskin]

Doesn't all the material fit into a single disc? I must admit that I personally would prefer to have it all on one DVD instead of two. It is easy to navigate through the meny if you want to see the bonus parts or games or what ever it is that follows. Why not offer an alternative; a single disc release for those who wants all of it in one place, and a 2-disc for those who are interested in 2-discs?

[AwallaceUNC]

DVDs are limited in storage capacity. Single-layer DVDs usually hold around 4.7 gigs and double-sided and dual-layer DVDs can usually hold no more than 9.4 gigs. Both video and audio consume a lot of storage space (if you ever load a video onto your computer, you'll see this). Therefore, there comes a point where adding more to a single disc is virtually impossible. The video and audio can be compressed so that it takes less disc space and more can be added, but that comes at a loss of quality. Therefore, the less that is crammed onto a single disc, the better the quality (generally speaking). After about four hours or so of video on a DVD, you'll usually find contents being spread over to a second disc. TV Show DVDs often pack more on a disc than movies, but you'll still rarely find more than 8 or 9 half-hour episodes or five hour-long episodes on a disc.

Most double-disc DVDs do actually require the second disc. There are some exceptions (<i>The Lion King 1 1/2</i> comes to mind), but even then, it's arguable that you've at least gained some quality by adding the second disc. Studios have begun to offer single-disc alternatives for many titles at a lower SRP, but they come with far less material.

Now, it's a different story with blu-ray. I'll leave that to a rant by 2099net on double-disc blu-ray sets and bonus features.

-Aaron

[2099net]

Well. I don't actually mind 2 disc sets on Blu-Ray or HD DVD releases, especially if all or most of the supplements are in HD.

However, I do have a problem with Disney UK advertising commentaries on their Blu Ray releases, both in Press Releases and on stickers on the packaging listing the supplemental runtime, because not only is that being lied to, but the reasons for dropping them are somewhat laughable considering BD50s were supposed to be the answer to everything!(and Disney's still at it) If space on a BD50 is at such a premium that even a single DD2.0 commentary track cannot fit on, then does the European "Dead Man's Chest" really need German/English/Italian in both DD5.1, DTS MA and an uncompress English 5.1 PCM track? The US release managed without DTS, and from what evidence I can gather most Europeans prefer to view movies with the original English soundtrack.

But I don't have a problem swapping discs over, and I suspect a lot of people here don't on their 2 disc Disney releases. Most of the time its not as if you would want to watch the movie, view extras on a second disc, and then go back to viewing the movie again in one sitting, so the problem is almost non-existant. And even if you did, you'd most probably be getting up anyway for a refreshment or bathroom break. If having to have 2 discs is the only way to get all the supplements from the normal DVD release on, I'm all for it.

[roswellian]

I have a real problem with Disney charging $30 for their 2-disc releases now. I bought POTC : Curse of the Black Pearl for $19.99 when it came out and now POTC : Dead Man's Chest has been out for well over a year and the 2-disc is STILL $30.00. This is ridiculous to me, $19.99 for 1 disc bare bones versions is ridiculous!

[Rumpelstiltskin]

So it has to do with the quality then? But most Disney movies are shorter than four hours, even with bonus included. Unless it becomes visible even before that point.

Now when we have Blu-ray, which is capable of containing a lot more data, I would assume we could get all on one disc, even if the movies as high-def demands much more space.

The single-disc alternatives sounds either way as a good offer. I have never cared about the games and such. The only kind of bonus I think is interesting is some documantary about how the movie was made and some of the history behind it.

[mikemgmve]

if you want to check videohelp.com - you can look at their section on dvd to read about compression rates.

Four hours on a single disc would definitely be of a likely lower-quality.

It's hard to tell when people use dual-layer discs as well, which expands quality, but is a more expensive medium.

I'd say no more than 2 hours per 4.7 gb at optimal quality.

[2099net]

Now when we have Blu-ray, which is capable of containing a lot more data, I would assume we could get all on one disc, even if the movies as high-def demands much more space.

Yes, but a Blu-Ray (or HD DVD) image is SIX times the area of a standard DVD.

A 1 x 1 image is only 1 pixel, as shown on by an X here:

X

Yet a 2 x 2 image is 4 pixels. Even though the image has only doubled in size, it has quadrupled in area.

XX
XX

This is how a full 1080p image is 6 times the size of a standard DVD image, even though non of the actual image boundry measurements has increased 6 times. The area increases exponentially.

Yet the maximum storage space of a Blu-Ray disc is only around 5 times that of a standard DVD (50GB - give or take a few for formatting - against 9GB). So on the face of it, nothing is different, in fact if the same compression was used, Blu-Ray actually theoretically supports a maximum content runtime which would be less than for the standard definition version on a normal DVD.

However, both Blu-Ray and HD DVD support advanced compression codecs over DVD's, and as a result they are theoretically able to hold more content as a result (AVC and VC-1) – as the full High Definition image is compressed better than DVD's MPEG-2 codec. But this advantage is somewhat neutralised by the ability of both High Definitions to offer uncompressed, lossless audio tracks, which take up considerably more room than the compressed Dolby Digital and DTS tracks on a normal DVD. HD DVD rarely offers uncompressed soundtracks though, because it has a maximum capacity of 30GB – a full 20GB less than Blu-Ray.

So put a reasonable length High Definition movie on a Blu-Ray disc (say 2 hours or so), add in an uncompressed soundtrack (PCM), a number of alternative soundtracks, a few special features (say another 40-50 minutes) all in HD, and you're pretty much coming close to the capacity of the medium if you want to retain quality.

This is the reason why lots of Blu-Ray or HD DVD discs have their supplements in standard definition rather than High Definition, especially on HD DVD which has less storage to play with.

Personally, standard definition supplements don't really bother me too much – most "making of" documentaries or cast interviews are mainly "talking heads" anyway, which I don't think need to be seen in High Definition. But supplements like Deleted Scenes, Theatrical Trailers, Music Videos and the like should definitely be presented on High Definition discs in High Definition.

[Rumpelstiltskin]

I guess we just have to wait for the Holographic Versatile Disc (HVD) then. But if it is possible to squeese the feature and some high-def extra material on a Blu-ray (or DVD for that matter) which combined is no more than a couple of hours, and some behind the scenes look in lower resulotion, then maybe a single DVD could be an alternative in the future.

Fram what I understand, HD DVD is built on the same technology that gave us the DVD, while Blu-ray is based in new technology. If DVD technology can be developed into HD DVD, it should mean that Blu-ray has a lot of future potential, making it possible to store a lot more information than is possible today.