MAMEWorld Forums - EmuChat - Re: Question about ALG driver status

> Using one of the last produced LDPs, would assure better quality output, than a model from the
> eighties.

Maybe.

Particularly towards the end of Laserdisc's life, there were a number of cost-reduced players released. While I don't recall specifics, many of them had inferior output to models that were over a decade old at that point. I understand your point that later models *should* be better, but that wasn't always the case. Hell, even in the '80s there were noticeable variances in playback quality and features between machines - which is one reason why industrial players were generally preferred over consumer-grade models.

> It is out of question, that a latest model, will output more decent
> quality, but the medium that is played is 90% junk in terms of quality. It is not a
> premium LD from Star Wars New Hope.

Even some of those Star Wars: A New Hope discs are suffering from laser rot. On a long enough timeline, all of them will. It's just that the laserdisc games have had longer to get to that point and so have statistically-greater instances of degradation.

> And Firefox, is one of the best looking games here. 90% of the LD games will look way
> more ugly. They where produced very fast and very cheap with the lowest eighties
> technology.

I disagree with that statement to a certain point. Remember that LD technology was not cheap at the time or over its lifetime, and that many games used multiple revisions of or completely different players during their production runs as reliability issues (which were usually, but not always, mechanical) surfaced. The players could only be bought in from the manufacturers at specific price points, and pressing LDs may have actually been *more* expensive for games than retail titles due to the relatively low numbers of discs produced.

As for the PCBs, wiring, controls, cabinets, and all other components that would be common to any arcade game... Sure, those would have been cost-reduced by the accountants as much as possible prior to production. But the LD hardware itself was going to account for a significant chunk of the overall manufacturing costs of each machine, and that was a cost largely controlled by the supplier of that hardware.

Now, one thing that we don't control (or really have good insight into) is the quality of mastering and/or pressing that may have taken place during disc production. It is possible that certain games may have used lower-quality processes in this regard as a way to reduce unit cost; this almost certainly will have an effect on both disc longevity and playback quality outside of the capabilities of the players themselves.

However, this is an unsolvable problem as we're working solely with the media that was generated under those circumstances, and even the greatest LD player ever made can't make a disc pressed from crappy source material look better than the material on the disc itself. If we had access to pressing masters things might be better to a certain point, but I'm willing to bet that by now all of those are long since discarded and/or destroyed.

> Going the route of not designing any new hardware, using a digital i/o card would be
> doable, it's just a lot of cash to spend to then find yourself limited by the 8-bit
> ADC in the LDV8000. Better results could be had by using an A->D card and capturing
> the composite out from a player with an analogue-only path from disc to composite
> port. I looked into this when I started, but I couldn't find a cheap card which
> retained the composite signal without processing it.
> Dave talked about cheap cards in a 4 years old thread. A Blackmagic is not even cheap
> today, but a lot more than 2010. More important, it doesnt process the composite
> signal, what comes in, comes out with interlace/fields or without (depending on
> input) and with VBI data.

OK, so here's a question from my somewhat limited understanding of how NTSC video actually works: what options exist other than a Blackmagic card? Basically, I'm wondering if this is something that couldn't be accomplished with the use of studio equipment in a pre-processing phase ahead of digital capture on some other equipment, or possibly even the same as proposed.

My thinking is that if the specific fields required can be broken out to a separate digital stream (or frame), the codec that captures and plays back the digital file can take care of the combinatory problem at playback.

This won't capture an 'original' frame, but then again trying to completely reproduce an analogue signal in a digital medium is a path to madness. You made that point very well here:

> "If good enough is not good enough, and
> you want an absolute perfect preservation of an analog medium, then of course there
> is no practical way of digitizing the signal. At that point the problem will be
> unsolvable.". Even with the intended rocket science setup, the result can differ from
> one laser to another laser, cables used etc.

Which brings us back to the point earlier in the thread that what constitutes acceptable losses need to be determined in advance and worked with to preserve as much of the original *as possible*. We know that we can't move everything on the disc from the analogue to digital domain in a perfect reproduction, so rather than getting bogged-down in worrying about that specific problem we should seek to find a workable solution to it.

> The last Blackmagic card, that has composite input and does 525i and 525p with VBI
> capturing, samples with 10bit 42 which is more than enough for SD material. Also the
> Pioneer CLD-D925 (1996) has a way more decent signal path, judging by all reviews i
> have read about this model (it even has PAL/NTSC), it sadly has no RS 232 connection
> and so it falls out for my choice of capturing.

There are likely several ways in which this issue could be worked around, but one that springs to mind is the following:

Homebrew an interface allowing a PC to directly piggyback onto the IR port for the remote control and frame-step from the PC as needed by faking IR frame seek commands; if the IR port can accept direct input of specific frame numbers, bonus.

Whether or not this will allow access to frame zero is another question, however: that capability may be reserved for the player internally and may not be user-accessible from the remote. In that case, start tapping the busses that govern this behaviour and see what sort of command injections might be possible.

Here's a thought: what did Digital Leisure do to accomplish their transfers? What was their source media, and how did they digitise it? They likely didn't care about things like VBI info since they were transferring to DVD, but it may make for an interesting comparison against methods commonly at one's disposal. It may also be completely pointless as this is an area of research that could easily lead to 'they crammed it into an MPEG at source', but could generate some useful info.