DVD Extras: A bit of background

Someone asked on Twitter a while ago if anyone knew the history of DVD extras. Since my brain is a giant seething mosh pit of this sort of thing, I told him I'd try to get around to posting some sort of datadump on the topic soon. Here be.

DVD extras are not actually unique to DVD. So far as I know, they began to appear on laserdiscs, partly as an incentive to purchase the disc-based copy of the movie rather than the VHS tape, and partly as a way to show off.

Videocassettes are an entirely linear format. From any given point, your only choice is to access the next point along the tape, either backwards or forwards -- all the REW and FF buttons do is access the linear sequence of tape segments veryveryfast, which is why a lot of VCRs can and will give you some sort of (possibly torn and garbled) picture when you do it while the tape is running. Film, the very first home video format, works similarly; the only way to get to a specific frame is to wind the film onto and off of spindles until you find it.

Laserdiscs do not work like this. Although they aren't a digital format -- the picture is encoded in FM modulation on the surface of the disc, roughly like it is for over-the-air analogue broadcast -- they offer what's called "random access", just like CDs and DVDs. You can put in a time or frame number and the player will skip directly to it. Most players, in fact, use the same iterative seek process that CD players do: The LD player has no notion of exactly where things physically are on the disk, so it positions the laser pickup somewhere in the middle, checks to see what time/frame it's looking at, and then hops forward and backward until it zeroes in on the spot it wants. This ability to hop around on the disc made it possible to include more than one "program" on a particular laserdisc release, such that the viewer wouldn't have to either watch the entire movie or spend ages mashing FF to get to it.

(This ability also, incidentally, allowed laserdiscs to be used as a source of full-motion video in arcade games like Dragon's Lair and Space Ace, both of which are "Press X To Not Die"-style button-smashers featuring animation by Don Bluth Studios. The branching function of the LD player was used to show the story in short snippets whose content and order depending on whether you told the hero to go left or right, to dodge before he gets toasted by the dragon, etc. This also meant that the hero could get stuck in a loop -- there's nothing stopping the LD player from resetting and giving you the same clip a million times in a row, if you keep getting lost in a maze or something. Because LDs are a non-contact playback format, this didn't wear a hole in the disc like it would if you tried that with something like a vinyl record. Although it does tend to piss off the people pumping quarters into your machines, if you do it too much.)

Specifically putting things like documentaries and behind-the-scenes content on laserdisc releases actually came about because of something that was otherwise a nasty disadvantage, which is that LDs only hold 30-60 minutes per side, depending on the encoding. Budget releases often used 60min sides to split a 90min movie across the A and B side of a single disc, but 30min sides gave substantially better video quality, which forced high-end collector's editions to split films across three sides of two platters, and left an empty B-side. Most LD masters left empty sides blank, stored a single repeating sequence that told you to turn the disc over for the program content, or simply pressed the A-side twice so there was no way to load the last platter upside down, but there was no reason it couldn't be used for bonus stuff instead.

The first company to do any of this was Criterion, who invented and then specialized in what are now known as "special editions", and who are still very much in business putting the things out on DVDs and Blu-Ray. Their range was aimed at the kind of serious cinemaphiles who would gladly pay extra for higher-quality video (which meant extra platters), restored footage, and special package inserts giving historical context and trivia for the film; some brilliant soul just went the extra step and asked the studios if it was all right to put cut scenes or behind-the-scenes footage on what would otherwise be wasted disc space. The first LD with extras that I am aware of is their 1984 release of Citizen Kane, which came with production stills and the film's original trailer.

Laserdisc spec also allowed for one stereo analogue soundtrack and up to two additional uncompressed CD audio soundtracks per program segment. This was originally intended to be used for bilingual LDs, and several movies were released with English on the master soundtrack, and Spanish or French on a secondary stream which could be accessed with the remote. Criterion was the first company ever to think of filling one of the additional allowed soundtracks with a scene-by-scene commentary instead, which they did with their second 1984 release, King Kong. Criterion loved these things, and in fact there are still commentaries recorded for Criterion projects sitting in the vaults that have never been released in any format, some of them featuring filmmakers and actors who have since passed away. They also often recorded/mastered new extras for their Criterion Collection DVDs, leaving some of their best commentaries and visual essays orphaned on a format that no one has pressed anything for since 2002.

Other formats technically had the ability to hold extras, but for whatever reason didn't bother. RCA's SelectaVision (a "capacitance electronic disc", basically a conductive record played with a stylus) allowed for multiple audio tracks, and several CEDs were released in English/Spanish, but no one seems to have bothered trying to put commentary on any of them. CEDs did feature a sort of random-access mode, but for various technical reasons, it was to the minute and not to the frame, and it was both more difficult to master and much harder on the player to display still frames, as LD could do with ease.

VHS tapes occasionally came with extra features during the very last days of the format, but these were cribbed from the equivalent DVD releases and generally just tacked onto the end of the tape.

DVDs acquired "Easter eggs" through an entirely different route. These come about because DVD players are rudimentarily-programmable critters all on their own. (Some LD players, like the ones used for the laserdisc games mentioned above, could be controlled from an attached computer, but independent of that few if any had any features beyond playback, pause/still display, and time/frame/chapter seek.) Computer programmers have been putting extra surprises into their creations ever since they figured out how to hide it from the Grand High Poobah who controlled access to the mainframe, and they carried the tradition on to the interactive menu routines of DVDs. There simply isn't a way to do that on laserdisc -- the closest you could come would be to include a chapter at the end of the side which is not listed on the LD insert, and to insert a "display still" code at the end of the previous chapter so the player would freeze-frame rather than playing through to the "hidden" content. This would be roughly equivalent to some of the simpler methods for hiding bonus tracks on CDs. I'm unaware of any LDs which are coded like this, although if anyone else knows of one, please tell me what it is! I am a complete dork and I love this stuff.

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