How to get AC3 from RF source like laserdiscs?

[persfave]

I'm trying to make a DVD of an old laserdisc. This is usually no problem, because I can hook up my laserdisc player to my G5 through the Hollywood DV Bridge and just capture into iMovie.

Here's the problem: I have a bunch of titles that have an AC3 track (which I want to use on my DVD). The only way to get the AC3 track out of the laserdisc player is through an RCA jack (not optical).

My question is threefold:
1. Is there a way to get the audio into my computer as an AC3 track (pass-through the DV Bridge or something like that)?

2. Is there any software that will help my mac recognize the track as an AC3 file? (I have A.Pack that was bundled with my DVD Studio Pro 2...could that work?)

3. If I'm successful at steps 1 and 2, is there a simple way to sync the track back to video?

Any advice at all would be greatly appreciated!

[WiseWeasel]

Laserdiscs don't use AC3, do they? Was AC3 invented back then? Anyways, the answer is no, since there is no way to get the digital signal from the laserdisc, unless you can find a laserdisc player with optical audio out, and some solution for recording digital optical audio. Even then, you'll be capturing the decoded raw digital audio from the player, and not the original compressed digital audio track. Your DV bridge will not work for this, as it only converts analogue to digital and vice-versa, and not digital to Firewire.

[persfave]

Actually, my laserdisc player does have an optical out. The bad news is that the optical out is only stereo, not AC3.

I wonder if there's some kind of cheap hardware solution that can translate the RF out on the ld player to the optical in on my mac. The new G5s do have an optical in and can handle AC3... I just can't figure out how to get the darn signal from one machine to the other.

[AntnyMD]

As far as I know, the digital audio on laserdiscs is PCM stereo with matrixed Dolby Surround sound. It is essentially the exact same surround sound you get from analog broadcast TV, only in a digitized form. If you were able to rip this audio from a laserdisc, you'd still have just a 2 channel file, which has been encoded as L, R, C, RS (rear surround, one mono stream played on both rear speakers).

There is a small possibility that some laserdiscs produced well into the demise of the format offered a compressed digital soundtrack, but I've never seen one. All my laserdiscs that are collecting dust are all just big giant compact discs with analog video and PCM audio.

If you used a capture device to get the video and the audio, the PCM audio file created would be a near perfect replica of the surround sound available on the laserdisc itself.

[Kelso]

What you are looking for can be done.

You can buy a small hardware box that will take the RF out from a laserdisc and convert it to a true DOLBY DIGITAL coaxial or optical output.
You then take that coaxial or optical output and run it into your computer and record away.

Many companies make these devices.
Sony makes a good one...
http://www.sel.sony.com/SEL/consumer/ss5/home/homeaudio/accessories/mod-rf1_specs.shtml

I hope this help you.

[BJ_M]

As far as I know, the digital audio on laserdiscs is PCM stereo with matrixed Dolby Surround sound. It is essentially the exact same surround sound you get from analog broadcast TV, only in a digitized form. If you were able to rip this audio from a laserdisc, you'd still have just a 2 channel file, which has been encoded as L, R, C, RS (rear surround, one mono stream played on both rear speakers).

There is a small possibility that some laserdiscs produced well into the demise of the format offered a compressed digital soundtrack, but I've never seen one. All my laserdiscs that are collecting dust are all just big giant compact discs with analog video and PCM audio.

If you used a capture device to get the video and the audio, the PCM audio file created would be a near perfect replica of the surround sound available on the laserdisc itself.

There were many laser disks with both Dolby Digital 5:1 and even DTS 5:1

I have most of the DTS laser disks ..

[AntnyMD]

I'd like to know titles and SKU's, even though it's off-topic (so send a private Message through the system). It just stands to reason that if those titles were mastered and manufactured late enough in the life of the laserdisc format that they contained true discrete multichannel audio, it was meant as a gimmick and not as a standard. Playtime on the discs themselves wouldnt have been aided much by compressed audio -- the size of the discs themselved owed to the fact the video itself was not compressed.

As a final comment from me on this, with all the time, expense and learning curve on this, wouldn't it be simpler to just buy the movie on DVD (if available)?

[persfave]

Hey Antny, just a quick check here:

http://japanld.free.fr/list.php?type=laserdisc&list=ac3

comes up with a list of 882 laserdiscs made in the US and Japan that contained AC3 audio. That's from 1995-2001. It actually was a standard and not a "gimmick" by '96 or '97.

Obviously, if there's a DVD available, it's not worth the effort, but when I want a DVD copy of the Director's cut of The Frighteners with a 4-hour "making of" made by Peter Jackson, it's got to be a port from my LD box...

and Kelso, thanks for the pointer to the outboard box.

Anyone with any ideas about syncing? or a link to a good thread?[/url]

[BJ_M]

AntnyMD ac3 and dts were standards on laser disks ... not gimicks .. and did not take up any more room , as laser disks always had 4 channel audio ... two digital and two analog ....


there were 158 DTS laserdisks listed (plus the ac3 ones mentioned above)

[[*]_BonKerS_[*]]

Ha, its times like these where I believe that a sort of open-source 'no holds bared' psuedo piracy should exist, where if it isn't out in the format you want you have the legal right to put it there and share it for everyone until the studios make a legit release (and if you wanted it that bad to begin with you would probably end up buying the retail version in the end!)...

If you are hip to the illegal Movie scene you would have known that this very same 4 hour commentary which you speak of was spread across the internet a while back. Check this link out: http://www.vcdquality.com/nfo.php/nfoid12458.png?id=12458&show=image

That is the 'info' file for the movie. While reading this file will not actually get you any closer to getting your hands on those files it should be quite a tease seeing as how if you (and I for that matter) knew the right people you could probably be downloading this as you speak.

Good luck to you in your cross-format-conversion-conquest!

[persfave]

Thanks to everyone for the replies (so far). Now I'm on the hunt for that RF Demodulator...

[ima2hd]

WiseWeasel you are a RETARD! "Laserdiscs don't use AC3, do they? Was AC3 invented back then?" Maybe the ones that were made for Mars didn't! Sorry had to get that off my chest. I am glad there is a way to retireve the ac3 what about if you laserdisc player has a optical aswell a coaxial digital output. Thank You in Advance, Will

[chrishart1]

What you need is called an AC-3 RF demodulator. This is because AC-3 was stored in a modulated format on LaserDiscs, not in a raw bitstream state (as with DVD).

I'm not sure if anyone is currently making brand new demodulators. But I do know that there are frequently ones listed on eBay. I did a search with these exact words:
"ac-3" rf

I came up with 4 hits. It looks like these devices are now demanding a solid premium. I believe this is for two reasons: (1) to my knowledge, none are being made anymore, and (2) there are only like 5 or so receivers on the market which can accept an AC-3 RF input (and I believe they all cost more than $2k).

Good luck.

[AntnyMD]

You guys are acting like crack addicts. Learn to love stereo (and matrixed Dolby Surround) and move on to ENJOYING the film rather than remaking a laser disc on DVD.