[rescue] Laserdisc players Re: Hello?

[Grant Stevens]

Okay, here's the story:  

The original laser disc spec had 2 analog audio tracks.  They were 
actually encoded in the FM carrier with the composite video.  (The FM 
gets clipped into pits, see here 
http://repairfaq.cis.upenn.edu/sam/icets/opttech.htm about half-way down 
the page for the scary details.)  By today's standards, the audio 
quality was so-so (about like broadcast TV).    
A bit later (like 1980ish) they figured out how to encode digital audio 
on the same pits with the composite analog FM signal.  The digital audio 
encoding is almost exactly the same as CDs, but often contains Dolby 
Surround (same as VHS).  
Now, nothing new happened with laser discs until about 1993, so he vast 
majority of laser discs have (and most players support) both analog 
audio tracks and digital audio tracks.  So, most laser disc players 
you'll find out there on the market will play the PCM tracks just fine.  
By 1993-1995, only the oldest of laser disc players were relying on 
those analog audio tracks.  So, they started stealing space from one of 
the analog audio channels and putting a second digital bit stream in 
there, usually containing Dolby Digital (AC-3) or DTS.  Usually they 
left one of the analog audio channels for mono audio.  
So, only the oldest of laser disc players won't play the PCM audio 
tracks.  It looks like that Pioneer player falls into this category.  
Side opinion:  Don't knock the Dolby Surround that's encoded on laser 
discs.  I think it sounds a lot better than VHS.  There's probably more 
channel separation (so the surround channels works better), and the 
frequency range is better.  

Grant Stevens


Joshua D Boyd wrote:

>On Fri, Apr 05, 2002 at 12:06:43AM -0800, Robert Novak wrote:
>
>>	http://www.oz.net/blam/DiscoVision/Pioneer_VP-1000.htm
>>
>>I got it for $30 at a local thrift store 2-3 years ago, and I finally
>>found a remote at the swap last month for $10.  I believe it was the first
>>US consumer laserdisc player on the market. Could give a guy flashbacks to
>>the old drop-in disk platter drives.
>>
>
>The audio standards changed several times over the years (plain analog, 
>analog surround, plain digital, digital surround, etc).  Wouldn't that cause
>problems with newish discs on such an old player?  Especially since one of the
>newer standards stomped all over the original plain analog audio.
>
>OK, I double checked that.  The analog surround would just be Dolby Surround
>(ie what is used on VHS tapes).  Then they had uncompressed PCM digial audio,
>and then Dolby Digital (aka AC-3, the same as DVDs).  From the 
>alt.video.laserdisc faq, Dolby digital replaces the right analog audio 
>channel with the AC-3 data stream.  So, on AC-3 discs, you will get only 
>static from the right chanel on old analog players.  Maybe that player is
>newer than it looks if it isn't giving you trouble.  But then, it wouldn't
>be one of the first consumer models.