Best VP for Laserdisc playback? - Page 9

I've got some very good-sounding Analog-CX LDs. One of them is a recording of Dvorak's Sclavonic Dances, with video footage (converted from PAL, I think — anyway it mostly looks dire) shot in various places around Czechoslovakia, including the interiors of cathedrals, & a demonstration of glassblowing.

Most of them are anime discs, though, as is one of my two non-CX analog-only discs (Nausicaa — the other is a Space Archive disc, & who cares what that sounds like). The audio quality is, I would say, mostly of a high standard. I suspect the FM audio is more sensitive to mastering practices than PCM, & I'm just lucky in my choice of material.

Edit : I ought also say that I have dozens of dual-audio discs for which my preferred soundtrack is the one on the analog channels. Most of these, again, sound superb. There are a couple of clunkers, but they tend to be discs which aren't that great all around.

VHS HI-FI tracks had no dolby noise reduction. The far inferior linear stereo tracks did usually use Dolby noise reduction.

I think it's time to inject a little reality in to this thread for the benefit of joey here.

I was a big-time Laserdisc fan and collector. See my signature for evidence of that. I still cherish my LD collection. However, anyone attempting to join the format for the first time now deserves to be set some realistic expectations.

Laserdisc is an analog standard-definition video format. It was rated at 425 lines of resolution, which was significantly better than VHS (250 lines), but less than DVD (480). Although many Laserdiscs are "widescreen," almost all were non-anamorphic 4:3 letterbox. There were less than a dozen anamorphically-enhanced LDs ever released (most of them in Japan), and they are all incredibly rare and hard-to-find. See the complete list here.

By modern standards, the vast majority of Laserdiscs have terrible video transfers. The analog video format was prone to chroma noise, dropouts, crosstalk, and other distracting artifacts that have been virtually eliminated in the digital age. Some people may argue that they find these analog artifacts less distracting than some digital artifacts, but that's a "six of one, half a dozen of the other" argument at best.

The Laserdiscs that were considered back in the day to have "reference quality" video were mostly victims of heavy Digital Noise Reduction, Edge Enhancement, and other forms of electronic processing that we find quite objectionable today. We just didn't know any better at the time.

Laserdisc picture quality is also extremely dependent on the quality of the player being used. Entry-level and mid-range units are all basically crappy. LD/DVD combi units are complete garbage for both formats and should never be used under any circumstances. Any LD player from Sony should be thrown in the trash immediately. Only the top-of-the-line Pioneer models (primarily the CLD-D703 or D704, and the exotic models imported from Japan such as the HLD-X9 and HLD-X0) and maybe one Panasonic model (the LX-900) should even be considered for use with an HDTV. Even with these, the digitization needed to watch an analog LD on a digital display tends to interact badly and create all sorts of weird noise and artifacts unless you "massage" the signal with video processing in between.

Most Laserdiscs released from the mid-1980s forward have uncompressed PCM stereo audio. This can be decoded by Dolby ProLogic to give you a very basic form of surround sound. Dolby Digital 5.1 was introduced to the format late in its life, in 1995. It's a big pain in the neck to implement on LD (you need a compatible player and an external RF demodulator device). It's not at all worth the effort for the small selection of discs that offer it. DTS 5.1 came shortly afterwards. It's a little more straightforward to implement (not much different than a DVD player), but has an even smaller selection of titles, most of which are collector's items that sell for a lot of money.

You can spend many thousands of dollars to optimize LD playback. However, in the end, the very best LD player connected to the very best external comb filter and the very best video processor, played back on the very best HDTV, watching the very best-looking LD ever pressed, will give you approximately the quality of a mediocre DVD. That's the reality of the situation.

Some of us who already have heavy investments in the format and large legacy collections of discs may find all this worth the effort and expense. But I don't believe there's any point in romanticizing the benefits of the format to someone new who has no experience with it. Jumping whole-hog into the format now will be a huge mistake, IMO.

My advice: Be patient and wait until you can find a Pioneer CLD-D703 or D704 on eBay, in good condition, for around $100-150. Connect it to the TV by Composite video (not S-video), and pick up a couple of discs that were released in the format's later years for a few dollars a piece. Stick to movies made in the 1990s. That will give you a sense of what to expect. You can decide from there whether you want to invest further.

One thing I would like to add is running a 2 channel PCM through a Dolby Pro Logic II processor will yield far superior results than a Dolby Pro Logic decoder. It was "II" in name only, and a completely different system with the name simply licensed by dolby laboratories.

I am an IEEE member and get the journal. I don't doubt at all there was a paper presentd as to how LD could in theory achieve outstanding S/N ratios. But was this ever achieved on a mass production basis?

I entered the broadcast business in 1980 and later moved on to post production in 1984. I therefore "grew up" with 1 inch type C tape. I also had the good fortune to be living in Los Angeles where one of the most famous laser disk rental and sales dealers was located - Dave's Video. LD was my home movie format for over 15 years before DVD. And I saw first generation 1 inch tape all day long at work.

I have never seen a Laser Disk achieve the S/N of 1 inch tape. Never! It may have been possible with laboratory disk samples and engineering sample players but not in my consumer viewing expereince.

We also were the largest rental house for the CMX 6000 film offline editing system that used laserdisks. We has three ODC 610 LD recorders in house. Now this was a different process than mass produces pressed disks used but the plastic disks off these were initially worse than VHS but got better over the years. They also made a glass disk blank from optical grade glass, very expensive, to be used in applications as kiosks. These were very good, on par with pressed disks but still no match S/N wise to a virgin 1 inch tape.

So while possible on paper, I never saw S/N above roughly 46db (that of course is an emperical observation measurment because I never actually measured it off a disk.)

As for the tangent servo, that's interesting info. I do know the mid 1980s players I owned were hetrodyne due to the tell tale unlocked subcarrier. Perhaps they found this to be more cost effective in some players

Heterodyne LD players? I've worked on a Pioneer LD-660 tube player, & LD-700 & CLD-V710 solid-state machine (based, if I recall, on the CLD-1010), & reviewed the service manuals for other players, & never seen a heterocolor circuit. Up until the introduction of sampling (CCD or digital) TBC, the players never had anything more complicated in the video circuitry than a 1H delay line for DOC. How did you determine that SCH phase was unlocked? I wonder if you might not have been fooled by timebase jitter somehow.

IEEE Transactions/BTR for 1974 November contains the paper "A Review of a Video-Disc System" by Kent Broadbent of MCA Labs (beginning on p. 338), based on the initial DiscoVision 20-minute CAV disc, which recorded a whole broadcast-standard NTSC signal, audio subcarrier & all. He gives a very clear description of the TBC method implemented in, to my knowledge, all LD players without a sampling TBC. As the servo loop for the spindle motor is controlled by a standard 3.58 MHz crystal oscillator, time-base deviations are due mostly to disc eccentricity & out-of-roundness, & mechanical vibrations, most of which are at frequencies substantially less than 15.75 kHz, so that line-by-line variation is rather small (about 20 nanoseconds in the worst case allowed by the specification for eccentricity, which is about 10 microseconds over the whole frame). The detected color burst is compared to the reference oscillator, & the error is used to drive a tangent mirror to vary the velocity of the read beam, keeping the line time & thus the SC frequency reasonably constant, although some variations still occur. Apparently a total variation of 5 ns was originally considered acceptable for reproduction by domestic receivers. See also Adler, "An Optical Video Disc Player for NTSC Receivers", Trans BTR, 1974 August, pp 230 et seq, which describes the matter in terms of the Zenith thin flexible disc system. After discussing their initial use of a heteorcolor system, with downconverted subcarrier & pilot tone, which made for a complex & expensive signal path, he discusses the attempt to eliminate this complication using a tangent servo system.
In the same paper, Broadbent gives the FM signal-to-noise ratio at 40 dB, equivalent to a 58 dB demodulated SNR, admitting that at that point the video SNR of actual pressed discs was limited but still "better than 40 dB". Winslow, "Mastering & Replication of Reflective Videodiscs" (IEEE Transactions on Consumer Electronics, 1976 November, pp318 et seq), gives CNR values from 57 to 66 dB for metal-film cutting, & 54 to 63 with photoresist mastering. This is for the condition with 3 unmodulated carriers, namely, video at 7.5 MHz, & 2.3 & 2.8 MHz for audio each 26 dB down from video. He does, however, report significant levels of intermodulation products, as high as -30 dB in one case, again with photoresist mastering. For injection molded replica discs, the figures are as much as 5 dB worse for IM, with little change in CNR.

My impression is that the actual discs were limited partly by pressing & mastering quality, as defects such as pit asymmetry or size variation would impair the SNR, & that considerable improvements were effected in these areas over the life of the format. I have a number of LDs, mostly later pressings, which strike me as being of excellent quality, & fully comparable with my experience of 1", although it has to be admitted that the heads on the C-Format machines in my living room are far from new. I also have some which are of mediocre quality at best, & the observation that some of these were pressed on the same equipment in the same years as the excellent ones reinforces my opinion that the source material is a strong influence.

Obviously, if the cutter is being fed from even a first-generation 1" tape, as is usually the case, the replica quality is going to be degraded from that to some degree, more so if the master is a tape-to-tape dub, which again was (to my knowledge) more the rule than the exception. More than that, if the mastering practices involved, or the actual masters themselves, were originally intended for VHS tape, there may well be substantial impairments. I have seen on disc what really looked like chroma noise from a colour-under tape, & wondered if it had been produced from a U-Matic source. This was from a company which did most of its business in the VHS market, & most of its LD releases had just the sort of muddy audio & video one would associate with that format.

I finally got around to moving on this. I just got a composite cable (from Blue Jeans) and will be hooking it up to my Pioneer DVL-91. the S-Video cable is also from BJC. I'll have both going into a DVDO Duo VP and will share impressions. MY setup is in flux now because I bought a Power Plant Premier which is DOA apparently; it'll have to go back. But for video comparison only, it shouldn't matter. For now I will do a jury rig and see what happens.

[quote=Josh Z;19657988]I think it's time to inject a little reality in to this thread for the benefit of joey here.QUOTE]

I didn't quote your entire post, obviously, but I have to agree with you. I am still an avid fan of LD but for mostly nostalgic reasons. I used to love getting a new boxed collector's set and I still maintain my collection and will not ever consider selling it. Heck, I still pick up a title every now and again on ebay. My urge to try to get the most from my collection culminated with my purchase of an LD-S9 a few years back. I have both of the Entech units and an Algolith Mosquito NR unit. I also have an old Faroudja broadcast comb filter sitting around somewhere. I haven't messed with any of it for some time but this thread has prompted me to do some fiddling around this weekend. Josh's last statement pretty much sums it up, though. The best of the best of the best is not going to wow you like an average DVD, for film originated material at least. I need to check out some of my concert discs to see how they look.

If I wasn't from the LD generation, I don't think I would pour a ton of money into a system now but as I said, I won't get rid of my collection because I have so many fond memories of the format. Plus, one of my dad's favorite films is Disney's Song of the South and we have two copies of it on Laserdisc. That's the only way we'll ever be able to watch it so that's another reason to keep my LD player running. I'm sure there are other films and concerts that are LD exclusive as well. Beyond that, and don't hate on me, but I'm all over blu-ray from now on.

Laserdiscs were overnight obsolete 14 years ago with the first computer fitted with a DVD player, letting you play DVDs at high res on your computer screen. You knew right away that it was over for laserdiscs, just waiting for the right large 1080p tv and projectors -capable of the resolution of a computer monitor. Prices of laserdiscs started to fall and this is when a lot of newbies invested wrongly in the media in my opinion.

I think that's an exaggeration. After all, with the right equipment you could upscale LDs almost as easily — through the computer, too.

I bought into LD then, in the belief that I could get very good deals on the material I wanted, which would probably not come out on DVD for many years, if ever. Experience has borne out those expectations.

Although my PC video card has an NTSC input, which is hooked up to one of my LD machines, I find I rarely use it. More often I use a little outboard conversion box to watch LDs on the monitor with the PC turned off, which makes for less noise.

Lasedisc was bearable only on a small screen
DVD was sensational on a computer screen by comparison

You could not see the potential of DVD on a NTSC tv and this is why initially
reviewers like those at Stereophile Guide to HT were just lukewarm about DVD

On a 8' screen with a G70 laserdisc could not hold a candle to DVD
I sold all my laserdiscs 14 years ago
Everything I care is on DVD

I think a lot of people would disagree with you there.

Certainly I've found the differences less than striking, on an apples-to-apples comparison basis. Of course, most of the material I like best is 4:3 aspect ratio, & what DVDs are available are often overcompressed, mastered from NTSC sources, or generally of poor quality.

Your viewing equipment & source material, of course, will make a difference.

Such a technical discussion about a format that really had nothing to do with tech specs to the people who invested in it. I, they, we all loved those big shiny discs because we loved movies and people who try and blow off that short period when they were the best things going do it because they have never felt the excitement of pouring through bins at Camelot Music or Tower Records looking for a favorite, plunking down $125.00 so you could own the Criterion edition of Robinson Crusoe on Mars, carrying it home, opening it up, pouring over that big gatefold and then sitting back and watching it. It was, and still is, a unique experience in the annals of home theater and I'm glad I was part of it. (Still am, by the way, having just watched The Last Picture Show just the other night.)

around for a short period ??????

LaserDiscs were around for almost 20 years offering the best quality
of any medium. it took DVD over 2 years to match the quality of LaserDiscs


Michael

Yea, it just seemed short to me since I was only collecting from 1985 or so. Plus, by 1998, laserdisc players were in only approximately 2% of US households (roughly two million) so it really was a niche market in every sense of the term. But like I said, still love 'em and it's fun to try and tweak them with new technology and see how much better than can look.

I finally got around to doing a comparison between S-Video and Composite inputs to my iScan Duo VP from a Pioneer Elite DVL-91 player; the TV is a Pioneer Elite 111FD.

It was only preliminary, and not of long duration, but on the one disc I tried (New Stars on Blue Note, 1989) the two were close, with the S-video feed a bit cleaner. I should try more when I have opportunity.

Try what you think are your best and worst looking LD's. Try a disc with with some really dark scenes. That should show you which signal path cuts video noise best. I used to use The Adventures Of Buckaroo Banzai to compare players or connections because it had so many problems. I could tell when the plentiful video noise was being cut down...

This is a topic I sometimes think about. I imagine the best option would be to mod a late model LD player with a good mechanical foundation and a high quality laser/pickup. The mod would attach a driver right after the laser pickup circuitry. Then, you could connect an external full-field TBC, before the LD player's ancient technology has had a chance to muck things up.

I'd use something like a Snell & Wilcox decoder or a Leitch DPS-475, which both give you component SDI out the other end. Some video processors surely have a full-field (or infinite window?) TBC.

Is there anyone out there that's doing this? Surely, there must be a couple old service techs who still know their way around some later model Pioneer Elites. I have a Pioneer CLD-97 set aside for just such a project.

There's some Lasedisc discussion in the "DVD Players" forum. You might get more response there.

Except you couldn't do it that way. You would get an RF signal, which would be useless. You would have to pick it up after the demodulator, at the earliest. I know someone one here modified a 97 or something of that sort by picking off the composite serial digital at the TBC ADC, to send it to an external processor, but my attempt to contact him to get the details didn't succeed.

Are you sure you're not thinking of the audio track? I believe LDs have baseband composite video. It's the audio that's FM-modulated. I'd probably just let the player handle audio decoding. Ideally, you might want to notch those bands out of the post-TBC composite video.

What I really want (which would require an implausible amount of free time and will therefore never happen) is to use a high-speed, high-precision ADC to sample the raw composite signal at the pickup. Then, I could do the TBC, filtering, composite video decoding, and post-processing in software. Hard disks have long been big & fast enough that the processing wouldn't even have to run in realtime. Capture first, then crunch on it for as long as it takes.

I've done extensive research on the LaserDisc system, so I can tell you for certain, & provide technical papers to document my statements if you prefer. Video is frequency-modulated onto a carrier in just the same way that it is on broadcast tape formats. Analog audio is frequency-modulated onto two additional carriers, & digital audio is eight-to-fourteen-modulated just as for Compact Disc. The four signals are summed together, with the audio FM & EFM signals at a level significantly lower than that of the video FM, & the result is clipped to generate a pulse-width modulated signal which is actually recorded on the disc.

It would be essentially impossible to record "baseband composite video" on disc for the same reasons that it can't be done on tape. The frequency range, from 30 Hz to 4.2 MHz, is simply too broad — seventeen octaves. On the other hand, impressing it on a carrier frequency of 8.1 MHz (black level) simplifies the situation enormously.

I might have to try pausing a scene and then switching. The input changes are not instant with my Duo VP and scenes can change during the transition when the signal is being re-acquired. But on the closing credits of what I was watching last night (Evelyn Glennie: In Rio/Fiesta), I didn't see any significant differences in the black background between S-Video and Composite.

A dark scene would be better for judging noise than black. With black, half of the (additive) noise will be clipped.

That's slightly inaccurate. Of the hundreds of color VTR formats to come into existence over the years, only a couple actually used composite video. All of the rest used a different modulation scheme for chroma. The reason being that composite mandates the inclusion of a TBC, which were bulky and expensive for most of the video tape era. (While TBCs are cool, my favorite analog video tech is actually the acoustic comb filter!)


I didn't know that. In particular, the PWM part bridges some conceptual gaps I had.

You might want to tell wikipedia, BTW. I didn't notice anything about PWM or the 8.1 MHz carrier frequency, but I might have missed it.

There's a reason I said "broadcast tape formats". Quad & 1" formats A/B/C were all direct composite, as well as D-2 digital, & that accounts for most broadcast plant before digitization. Admittedly, some broadcasters did use 3/4" U-Matic & later Betacam, but that was mostly for remotes & such as I believe.

Okay, okay. I think we've established that you're probably an even bigger video geek than I.


Hey now, that's a bit of a stretch. We were talking about TBCs and chroma modulation schemes, remember? Once you go digital, the chroma modulation scheme has nothing to do with TBCs.


Anyway, let's get back to the important stuff, shall we? Is this an area you're actively investigating? Has anyone just tried calling shops experienced in servicing LD players to ask whether they're capable of such mods?

Also, are the PWM decoders analog or digital?

Do you know whether the SDH phase is always fixed, on LDs?

BTW, on first glance I read this as Luma City! You can probably imagine my disappointment when I reread it.

As evidenced by the fact that I have an edit pair of BVH-2000 C-format 1" broadcast machines in my living room, & am trying to get rid of a pair of BVU-800s. And unless you have more than 500 anime LaserDiscs, I might be able to claim that I'm more of an anime geek! (But won't, because I'm not that big of an ass.)




If you mean SCH phase, ie, between horizontal sync & subcarrier, it's locked (not fixed, as there's a 180 degree per line shift, due to the odd-half-multiple relation between the line & subcarrier frequencies), by the simple fact that composite video is recorded. The 4-field NTSC sequence is disturbed during still-frame operation, but the chroma remains coherent on a line-by-line basis. On older players, the subcarrier frequency may vary somewhat over the whole frame, as the tangent servo may not be able to correct for 100% of the disc eccentricity, but holds the variation along a single line to less than 10 nanoseconds.

The decoding for the RF signal varies by player. I understand there are some models which do digitize the whole RF waveform, perform TBC on that, then de-convolve the various subcarriers & recover their respective signals. A more common approach is to do filtering in the analog domain, which turns the overall PWM signal (with a dash of PPM as well) into three FM signals & one EFM, & then demodulate in the analog domain, feed the EFM to a standard CD decoder chip, & digitize the demodulated composite video. There's no single standard approach.

At the moment I haven't really been pursuing player modifications, other than possibly adding a digital audio output to my LD-V8000 (already has AC-3 mode), which unfortunately requires replacing an 80-pin surface-mount chip, the CD decoder I mentioned as it happens.