Talk: Laserdisc

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I've heard more than once that the LD is actually completely analogue (at least for the video part, if not the audio), rather than digital like the CD. Can anyone knowledgable confirm and add info about this? --radiojon 07:29, 3 Sep 2003 (UTC)

That's my knowledge as well - a quick google found the following short technical description [1]. andy 07:39, 3 Sep 2003 (UTC)

I have read more than once that audio could be analogue or digital, but video was always the same(i forget which). What I never understood is: how on earth do you store analogue signal by anything other than depth(as in a record read by a needle)?Boffy b 00:12, 2004 Sep 26 (UTC)

I think this is how it works. The video signal is used to frequency modulate a carrier signal, and the resulting signal is clipped and stored on the disc as a square-wave-like signal. Each transition from pit-to-land or land-to-pit represents a transition of this FM video signal from positive to negative, or vice versa. When the signal is read off of the disc, the harmonics are filtered out, turning the square wave back into a modulated sine wave, which is then demodulated and turned back into video. Someone correct me if I'm wrong. --Arteitle 06:10, Sep 26, 2004 (UTC)

Contents

1 LD FAQ link 2 All of the above is true 3 More 4 Comb Filtering 5 DVL-919

LD FAQ link

> I've heard more than once that the LD is actually completely analogue

http://www.access-one.com/rjn/laser/legacy/ld96.html

The article author might want to link to the hosting page for the above, as there are numerous FAQs, some more recent than those linked from the wik article.

http://www.access-one.com/rjn/laser/laserdisc.html

All of the above is true

The Total Rewind VCR museum has the whole story, but in short it was released in 1980 as DiscoVision/LaserVision/VLP(30cm, all analogue, flopped), in 1988 as CD-V(20cm, digital CD sound, analogue video, flopped), and in 1991 as LaserDisc(same as CD-V, but 30 cm and sometimes with analogue audio as well, fairly successful).

Read all about it at [2]

More

Laserdisc is an entirely analog format where the video portion is concerned. Some people find Laserdisc slightly more attractive than DVD because it does not suffer from compression related issues and has a smoother more "film like" image. However, it was also prone to issues such as "crosstalk" which DVDs do not suffer from and DVD has 30% greater overall resolution. In addtion, Laserdiscs had the capability to store digital audio, a capability that was regularly made use of in the early and mid 1990s, up to 1997 or so when the format finally died. Dolby Digital and DTS debuted on the Laserdisc format. I have several websites earmarked which contain information on the development of Laserdisc, catalogs of titles that were released and even lists of which titles contained Dolby Digital and/or DTS sound. If you are interested, or have a general question, I can be reached via e-mail at OneActor1@aol.com

In the line "NTSC discs could carry two analog audio tracks, plus two uncompressed PCM digital audio tracks, which were generally CD quality or better." I was wondering why you added "or better" after the description of "CD quality". As I mentioned in my earlier edit comment, the specs for Laserdisc's PCM tracks are the same as CD: 44.1 kHz, 16 bit, stereo. --Arteitle 19:34, Nov 13, 2004 (UTC)

It was my understanding that the nature of LD-Audio storage allows for higher than CD audio quality. This is laregly the result of the audio being uncompressed, where it is compressed on CD. Basic listening tests have lead me to believe that this is both possible, and in some cases true. Although I suppose that this could be the result of mastering differences.

Your post is largely true and informative, except for the bit about CDs. Standard music CDs are uncompressed, but both the video and audio on DVDs is compressed which may be what you are referring to. Boffy b 20:51, 2004 Nov 15 (UTC)

Comb Filtering

Comb filters are a way of keeping chroma subcarriers from interfering with luminance signals (as a beat pattern) *when you mix them*. Clearly, if you're taking the video off the S-Video connector, that's not an issue.

If you can find a citation that the comb filter was explicitly intended to make the S-Vid out look better (as opposed to the composite out) which is *not* marketing material (:-), please post it, and I'll retract. Baylink 07:14, 4 Dec 2004 (UTC)

The reason a comb filter is always in the signal chain with LD is because the video is stored on disc as a composite signal. So using the S-Video output of a LD player means separating luma and chroma in the LD player (and using its comb filter), whereas using the composite output of the LD player means separating them in the TV (and using its filter). See [3] (part of the LD FAQ). --Arteitle 13:32, Dec 4, 2004 (UTC)

Well, I will be dipped in shit. I had managed to completely miss that it's composite on disc. Nice reference, BTW; is that in the main article? Baylink 22:19, 4 Dec 2004 (UTC)

Yow, don't take it so hard. :) Yeah, it's in the external links. --Arteitle 23:12, Dec 4, 2004 (UTC)

DVL-919

The DVL-919 is still on Pioneer North America's website but is NOT in production any longer. It's been out of production for the U.S. since around 2000. I verified with several Pioneer dealers, I also verififed that a few units are "floating about" but that Pioneer no longer consideres it a current model. The Laserdisc section of the 919 was borrowed from an older player in the CLD-600 series, which were never very good players and the DVD section is mediocre at best in comparison to most new units from Pioneer, Toshiba, etc... and Pioneer made the decision to drop it when support for LD fell through completely in the U.S.

Fine. But please *correctly* characterize your changes, don't take the website reference out of the article completely... and sign your damn changes.  :-) Baylink 22:15, 5 Dec 2004 (UTC)

I don't understand how I'm failing to properly characterize my changes. The reference to the DVL-919 being on the website is moot and doesn't need to be in the article. On the site or not, the manufacturer consideres the player dead and says they've ceased all production, as of 4 years ago. In any case, I'd sign my changes if I knew how, but I don't. I'm not entirely sure why it matters, it's not as if I'm filling the article with derogatory comments or bad information. You guys that desperate to track me down?