For those interested in Laserdisc preservation progress, read on.
Currently, the Domesday Duplicator hardware itself is stable, and has been since around September of last year. The designs, schematics, and firmware are available for anyone to download and build themselves, who wants to start capturing their own discs.
Meanwhile, focus has shifted towards improving the output of ld-decode, which generates an uncompressed video output from a capture file produced by the Domesday Duplicator hardware. This is the primary reason why there hasn't been much if any movement on the MAME front towards adding LD games quite yet: We'd like the output of ld-decode to be largely stable before starting to add a lot of LD captures. People already get cranky when they have to re-download ROM sets that are a few kilobytes to a few megabytes in size - the amount of wailing and gnashing of teeth would be astronomical if we forced people to redownload upwards of 100 CHDs the size of Cube Quest each time there's a major improvement in the output quality of ld-decode.
For those who want a demonstration of the current capabilities of ld-decode, here's a promo video that was released a couple weeks ago to mark the release of ld-decode rev4:
As an aside, it appears that ld-decode is at least partially capable of decoding raw RF captures from a VHS tape, given appropriate adjustment of the decoding parameters:
Similarly, there's also another person working on getting ld-decode to be able to decode the output of the "HackRF" project, which is a SDR (Software-Defined Radio) capable of broadcasting and receiving analog television signals:
The plan is for rev5 to be released on the 28th of this month (February 2019). Among other major improvements, it will hopefully contain EFM demodulation, which will allow for decoding the data contained in the Domesday discs, as well as support for decoding digital audio and AC3 audio on laserdiscs which used them.
Anyway, that about wraps up this update. I'll be replying with any other interesting screenshots that pop up in the #domesday86 channel on Freenode.
Looks great already so it can looks even better and it's really worth the wait plus
Quote: People already get cranky when they have to re-download ROM sets that are a few kilobytes to a few megabytes in size - the amount of wailing and gnashing of teeth would be astronomical if we forced people to redownload upwards of 100 CHDs the size of Cube Quest each time there's a major improvement in the output quality of ld-decode.
> As an aside, it appears that ld-decode is at least partially capable of decoding raw > RF captures from a VHS tape, given appropriate adjustment of the decoding parameters:
That's great news, there are some obscure VSH-based videogames worth preserving... What's the reference VHS player for capturing?
Quote: Meanwhile, focus has shifted towards improving the output of ld-decode, which generates an uncompressed video output from a capture file produced by the Domesday Duplicator hardware. This is the primary reason why there hasn't been much if any movement on the MAME front towards adding LD games quite yet: We'd like the output of ld-decode to be largely stable before starting to add a lot of LD captures. People already get cranky when they have to re-download ROM sets that are a few kilobytes to a few megabytes in size - the amount of wailing and gnashing of teeth would be astronomical if we forced people to redownload upwards of 100 CHDs the size of Cube Quest each time there's a major improvement in the output quality of ld-decode.
There's an understatement...
"Note to Noobs:
We are glad to help you but simply posting that something does not work is not going to lead to you getting help. The more information you can supply defining your problem, the less likely it will be that you will get smart-alec replies.
> Wouldn't composite output (or better yet S-VHS or component output) be much cleaner > than RF output?
Wooooow. We're talking about the RF signal coming directly off the video head or laser pickup, not the RF-modulated signal coming out a port on the back of the deck.
> For those interested in Laserdisc preservation progress, read on.
One thing that wasn't mentioned (since it was from a few weeks ago and mentioned elsewhere) is that they have combining two laserdisc rips into one "best" one working, with the idea being that one copy may not have signal dropouts that another would, etc.. So far, this was tested with two rips of the same laserdisc on the same player (IIRC) and still to be tested is combining a copy of the same disc from two different players, two different copies of the same disc on the same player, etc. There's a sample video demonstrating this but IDK where it is right this second.
> So far, this was tested with two rips of the same laserdisc on the same > player (IIRC)
Two rips of the same type of disc (either Domesday National South or Domesday Community South, I forget which) on the same player. Each disc had major bit rot, but the bit rot was on opposite ends of the disc. Ripping the same disc multiple times on the same player would be next to pointless. Dumping the same disc on multiple players, however, could potentially reduce some drop-outs, as a small percentage of drop-outs can happen due to mechanical effects rather than actual disc rot.
Edit: Clarified the difference between the two discs that were dumped, added more clarification as to what's useful and what's not.
> > So far, this was tested with two rips of the same laserdisc on the same > > player (IIRC) > > Two rips of the same type of disc (either Domesday National South or Domesday > Community South, I forget which) on the same player. Each disc had major bit rot, but > the bit rot was on opposite ends of the disc. Ripping the same disc multiple times on > the same player would be next to pointless. Dumping the same disc on multiple > players, however, could potentially reduce some drop-outs, as a small percentage of > drop-outs can happen due to mechanical effects rather than actual disc rot. > > Edit: Clarified the difference between the two discs that were dumped, added more > clarification as to what's useful and what's not.
Hi Just interested to know if there are any updates / progress with this project in the preservation of the laser disc games? I note that rev 6 is the latest revision which is a jump in revision since the lalt update in Feb 19. D
> Hi > Just interested to know if there are any updates / progress with this project in the > preservation of the laser disc games? > I note that rev 6 is the latest revision which is a jump in revision since the lalt > update in Feb 19. > D
The project is still moving forward. Rev 6 is expected to hit sometime in December. Currently most of the focus has been on PAL decoding, whereas most arcade laserdisc games are NTSC, but rest assured that both Matt Ownby and Warren are regulars in the IRC channel, so they're just as interested in all of us on the MAME team in taking action once the decoding stabilizes.
Although the PAL decoding has come along way there have also been a massive amount of updates for the generic code between both systems.
Dropouts are better dealt with.
Now has a system for post process to make a frame accurate output (Decodes the VBI to detect repeated frames / missing frames.)
Discs can be merged - WIP (using multiple samples of the same pressing you can remove defects such as scratches and pick the video with the lowest SNR)
Better analogue audio
EFM Track is now demodulated and decoded and has recently had a massive improvement in the accuracy.
I am hoping to go and sample a set of 10 identical Dragons Lair discs in the next few months which will allow testing of the combining of discs and provide a dataset that will allow the possibility to improve the SNR over the copies.
This is one of the most important and interesting projects for me, regarding preservation. I am really happy, that this project exist. However i am curious how MAME will handle interlace, as currently there is no real good solution for this kind of material.
Thank you so much for your efforts and cooperation.
Hopefully you can sample a Star Rider disc in the near future, I believe it would be a worthwhile target to see how well the Domesday Duplicator handles the (manchester) data encoded on that particular disc.
If I still had mine I would donate it to the cause no questions asked.
I actually have a two samples of StarRider in PAL but both are have major rot (Philips PDO discs) and were sampled about a year ago on a non calibrated player....
I also have a space ace disc to sample but have not got round to it yet.
> I actually have a two samples of StarRider in PAL but both are have major rot (Philips PDO discs) and were sampled about a year ago on a non calibrated player....
There was a PAL version of Star Rider?! Is there any hardware to use it?
The Mancheester data on the Star Rider disc is in the visible area of the video, so even a standard capture card does a good job with it. In theory, the ability to combine multiple Domesday/ld-decode captures could eliminate errors due to dropouts, but in practice I don't think this will matter for the data.
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