LAserdisc 5.1 question...

[chicagofilms]

Is there a way to capture a DD AC3 5.1 soundtrack from a laserdisc and put it on a DVD+RW? Can one of the newer soundcards do this?

I'd like to transfer a few laserdiscs to DVD but it would only make sense if I could keep the great DD 5.1 soundtrack.

Any help would be great!

[chicagofilms]

DD 5.1 aside for a moment, I have yet another question.

I'm using a Dazzle Hollywood bridge. If I capture the laserdisc and send it to the PC via DV, is there anything I need to be aware of regarding Pro Logic?

I want to make sure I retain Pro Logic when I convert the DV to a DVD. Do I need to do anythting special? DVDit PE will make the DVD with DD(2ch), will that retain the surround sound?

[flaninacupboard]

as long as it's not joint stereo, it should still be possible to extract prologic information from it.

[lchiu7]

DD 5.1 aside for a moment, I have yet another question.

I'm using a Dazzle Hollywood bridge. If I capture the laserdisc and send it to the PC via DV, is there anything I need to be aware of regarding Pro Logic?

I want to make sure I retain Pro Logic when I convert the DV to a DVD. Do I need to do anythting special? DVDit PE will make the DVD with DD(2ch), will that retain the surround sound?

Standard output from a LD player analogue ports is stereo or if encoded Dolby Surround. The Pro Logic part is really the decoding algorithm in the receiver. Not sure about the LD players that could output digital but I suspect again once converted to analogue the Dolby Surround was encoded in the Left/Right channels out of phase as usual.

Dolby Digital comes out as an RF modulated signal that has to be fed into a receiver with a special RF Dolby Digital input (getting rarer these days). So I would imagine it would be pretty hard to capture that using any regular video capture card

Larry

[ChrisX]

chicagofilms -

Are you sure your LD player send out digital sound, even it is in stereo? Do you have a special AC-3 decoder out, such as THX? I just don't know how are you connecting the sound?

My LD player sends out analogue stereo sound even though the disks themselves as having 5.1 surround sound or as digital stereo. This is what I mean, the music CD and the LD movie having digital soundtracks doesn't really mean I am listening to digital sound in the lounge room.

I am only getting the surround sound from the DVD player only with my digital receiver, not from the LD player.

A standard LD player sound out is usually as analogue stereo, 2 RCA jacks into the amplifier or receiver. This is as far I am aware of unless you have a very expensive LD player with the 5.1 surround out into the 5.1 receiver.

If you want preserve the surround or prologic sound into digital video in the computer, you will have a lot trouble, very hard to get with the cost to do it. To me, it not worth the trouble.

I have learnt somewhere recently that someone can get a special surround card for the purpose of listening 5.1 DVD on the computer. Creative DVD-ROM can play 5.1 sound into the special 5.1 sound card. You can check it out at creative.com: http://www.americas.creative.com/products/product.asp?product=218&category=4&maincategory=4

Anyone with any info on 5.1 sound card availibility, please tell us.
Thank you.

Good luck to you, chicagofilms.

[lchiu7]

chicagofilms -

Are you sure your LD player send out digital sound, even it is in stereo? Do you have a special AC-3 decoder out, such as THX? I just don't know how are you connecting the sound?

My LD player sends out analogue stereo sound even though the disks themselves as having 5.1 surround sound or as digital stereo. This is what I mean, the music CD and the LD movie having digital soundtracks doesn't really mean I am listening to digital sound in the lounge room.

I am only getting the surround sound from the DVD player only with my digital receiver, not from the LD player.

A standard LD player sound out is usually as analogue stereo, 2 RCA jacks into the amplifier or receiver. This is as far I am aware of unless you have a very expensive LD player with the 5.1 surround out into the 5.1 receiver.

If you want preserve the surround or prologic sound into digital video in the computer, you will have a lot trouble, very hard to get with the cost to do it. To me, it not worth the trouble.

I have learnt somewhere recently that someone can get a special surround card for the purpose of listening 5.1 DVD on the computer. Creative DVD-ROM can play 5.1 sound into the special 5.1 sound card. You can check it out at creative.com: http://www.americas.creative.com/products/product.asp?product=218&category=4&maincategory=4

Anyone with any info on 5.1 sound card availibility, please tell us.
Thank you.

Good luck to you, chicagofilms.

A modern LD has two tracks on it, a digital stereo track and an analogue track (to cater for older players). A modern LD player could read both. For the digital track AD conversion is done in the player and an analogue signal output. For the analogue track, presumably no conversion is done. You could select either the digital or analogue track to listen to and one some discs, the analogue track(s) were used for extras like Director's commentary etc. On some higher-end discs, the digital unprocessed signal is available. This could be either fed to an external DA converter (or to the digital input of a receiver) for those who felt their external converters were better and for the DTS encoded LD's this was the only way to get the DTS signal out.

When Dolby first came out with AC-3 (DD) it was for Laserdiscs only. They did this by encoding the DD signal as a RF modulated signal on the left analogue channel. So you could actually listen to this as a constant hiss or static noise. To properly decode this signal needed either a LD player that had the ability to internally route this signal out through a separate jack or modify one to allow it to do that. I did the latter - had a Pioneer LD player modified with a chip to extract the signal from the disc and output it as an RF modulated AC-3 signal. This could then be input to a receiver that could accept this signal (which as I noted before) is a dying breed.

So connect the sound I did two things:

1. Connect the analogue ouput of the LD player to some line in on the receiver. Use this for non DD discs

2. Connect the RF modulated output signal to the RF AC-3 input on my receiver. So when I had a DD disc, I would select a different input on the receiver and hear all 5/1 channels



1. used the analogue out

[ChrisX]

lchiu7 -

Thanks so much and very informative on LD sound out. Good on you telling me.

I have a Pioneer LD Player too, the model I use is CLD-1450 and this one plays both NTSC and PAL. This one unfortunately I can't select the soundtrack I want to hear, anologue or digital. This is why Director's commentary listening is useless to me.

It doesn't have RF modulated output signal to the RF AC-3 input of the receiver. It is RCA jack out for anologue only to the digital receiver. It is ordinary stereo sound, thats it.

My player selects the digital sound as default, otherwise selects the anologue sound on older non-digital disks. I only have a couple of older analogue sound LD movies and one of them is the original Star Wars. This was a long time ago, long before 1990.

I don't use the player very much even though I have a sizable number of LD movies in my collection. I am now using DVD these days with my Pioneer surround receiver. The sound is awesome.

[e.lectronick]

The interesting thing I noted about the AC-3 jack is that it's the same rca style jack used in S/PDIF digital PCM connections. I wonder if it's possible to get a bit of software that allows you to tell your computer that it's AC-3 instead of PCM data coming through that jack and record it to your harddrive that way?

I've been wondering about how to get Dolby Digital into my computer for some time, now, and the only thing I've come up with is to decode first, then record into the computer using a multitrack recorder such as Protools LE with the Digi001 breakout box. Seems kind of a pain and somewhat expensive since so many cheaper soundcards have a S/PDIF input/output already on them.
I suppose it's possible to just use the PCM encoded digital outs to record into your computer, and settle for using a Dolby Surround, Dolby ProLogic or PrologicII decoder to get surround sound once you've laid it all onto DVD.

By the way, how close are we to getting DVD burners that can burn dual layer discs? What are they called anyway? DVD9?
-E.

P.S. Afterthought: Are there any Receivers which decode surround *and* have a digital outputs that could run to the computer as PCM? I figure once you decode, you could send the 5.1 signal digitally without any loss.

[therick]

"By the way, how close are we to getting DVD burners that can burn dual layer discs? What are they called anyway? DVD9? "

Never gonna happen. Those discs have to be pressed.

[DOGLOOP]

OK

AC-3 RF is not the same spec as SPDIF (sony/phillips DIGITAL interface)
AC-3 RF is modulated as an analog radio frequency and must be de-modulated 1st to a digital signal (bitstream) before ANY receiver can then process thru it's DAC (digital/ analog converter) to 5.1 DISCRETE analog channels.

Now, it may just be possible to capture the 5.1 DD bitstream after passing thru the de-modulator 1st & then to a SPDIF capture card. If not the only idea that comes to mind might be to capure after the receiver as 5.1 individual *.wav files & use your DVD authoring software/hardware to create a solid 5.1 Dolby Digital or DTS from the *.wav's

Please post if this helps or if there are any additional ideas out there for this type of audio capture.

DogLoop

[e.lectronick]

DogLoop,
Thanks for the ideas. I was thinking that it might require some kind of hardware hack. I don't suppose you know of any video capture cards or soundcards that have an AC-3 input? Many of them like the Sound Blaster Audigy cards will output AC-3 if you're watching a DVD on your computer, but I think it's a conspiracy of the industry to keep inputs off limits so as to restrict our ability to make perfect copies of commercial DVDs. Makes sense anyway if there's no other explanation.

I looked at the Canopus ADVC100 and the Raptor card, and that really looks like the best compromise for the price. I'm wondering if it'd be possible to get inside the machine and bypass the audio A/D converters and send the pure digital PCM signal from the digital out of my Laserdisc player. Then, at least I wouldn't suffer the signal degradation inherent in converting to analog then back again. Of course I have absolutely no idea how this would be done, but it's just a thought.
Whaddya think?
-E.

[thxkid]

I have one of last Pioneer's top of the line Laser Disc players they made, it not only has the AC-3 out but also, coxial and digital out also, all 3 ways to output DD 5.1, it is one of those players that plays both sides had digital effects and a TBC also I think its model 970 or 980. Has dual S-video, Video and RCA outputs. Its a big SOB and heavy as hell.
I have a Sound Blaster live 5.1, never looked to see if I can imput to this sound card? umm may try sometime.

[therick]

yes, I have a digital out on my LD player as well...would it be possible to record the DD 5.1 to put on a DVD? This would be great for my Star Wars....

[e.lectronick]

Star Wars is exactly what I'm doing.
I want to preserve it as best as I can because Lucas has said he will *never* release the original on DVD, preferring the Special Edition as the definitive film. Ugh...
Anyhoo, I'm scooting around the net looking for any capture cards that have digital audio inputs. I'm almost considering paying big $ for one, doing the job then selling it. I really don't care about any other films as they will all eventually be released on dvd unaltered.
Well, except maybe for ET, but that wasn't my favorite anyway.
And, by the way, how are you gonna shoot somebody with a flashlight?

-E.

[e.lectronick]

Hey,
I just saw this ad from JVC in March 2000 for the JX-S777.
For the listed price you can probably get one of these for cheaper, now.
Here:
http://www.jvc.com/company/press.jsp?pressType=2&item=75
If it's what I think it is, it will allow the combination of S-Video and optical digital audio from an LD player, and output a Firewire DV signal to your ADVC100 where you can switch on the sound locked to video button, and record it all to your harddrive.
I may not have read it correctly.
I was also thinking that a DV camcorder with digital audio inputs and s-video inputs with a firewire output would do the job too, and you'd have a camcorder to use.
Any thoughts?
-E.

[DOGLOOP]

check out this item:

on e-bay

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1379854218

now this do-dad converts the rf to SPDIF or possibly toslink???

ok now this could be captured on a comercial capture card if it has SPDIF.

I thought i saw something like that for recording audio as a capture-card.

Is that what your actual question is, "what type of capture card can record raw SPDIF input?"


Post if that is your question, please .... hope it helps.

DogLoop

[DOGLOOP]

Wait !!!!


Did you say that you are converting the 'Definitive Collection' Set, and NOT the Special Edition? ....... Reason i ask is:

Special edition have 5.1 DD ac-3 RF, But definitive collection is two channel PCM stereo only.

With a LD player w/ a toslink output &^ any toslink in type recorder (mini-disc, Standalone CD recorder ... etc.) you CAN record unchanged PCM from the LD (+/- any bitstream errors) directly. however, if you are asking are there any capture cards for sale that record PCM this way while allowing you to cap the video in perfect sync, i say good luck

DogLoop

[BJ_M]

some info

http://www.cybertheater.com/HW_Reviews/AC-3_Mod/ac3_mod.html

[e.lectronick]

check out this item:

on e-bay

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1379854218

now this do-dad converts the rf to SPDIF or possibly toslink???

ok now this could be captured on a comercial capture card if it has SPDIF.

I thought i saw something like that for recording audio as a capture-card.

Is that what your actual question is, "what type of capture card can record raw SPDIF input?"


Post if that is your question, please .... hope it helps.

DogLoop

Actually, that item is interesting to me because it might solve the problem. I already have an Audiomedia III card which has S/PDIF in and out. That's not my problem. I was really wondering if A: any video capture cards could record AC-3 signals, or B: if any decoders could transform AC-3 signals into multichannel PCM signals for use with S/PDIF or other more common digital formats. But the latter would still require me to somehow sync the audio to the recorded video as I'd still have to get them into my computer through seperate paths.
The S/PDIF PCM inputs are only stereo, unfortunately, so I would need at least three sets of inputs or some kind of multiple input breakout box that hooks up to my computer via Firewire or something. While it's incredibly common to find multiple audio connections for multitracking audio, its interesting that you don't see that on Video solutions. The bes I've seen for an affordable price is the ADVC-100 and that's just analog stereo. Like I said, I think the industry doesn't want to make it easy for us to make our LD dubs too perfect. They'd just prefer we go out and buy the DVDs instead.

Regarding the Definitive Collection being 2 Channel only, yeah I know. I just was wishing that it could be a simple one box solution. Ah, if wishes were fishes...
-Erik.

[BJ_M]

there are several all in one video capture and multichannel audio cards around -- all are expensive though ...

[e.lectronick]

Really?
Would you happen to know some of them? I'm more curious than eager to buy, as I'm on a shoestring budget, but I'd be interested to know what's out there.
Thanks.
-E.

[nickel]

How about this idea to get the AC3 off of a LaserDisc. It's extremely time consuming and difficult and requires some hardware and expensive software. But let me throw it out there and you all tell me if it's even plausible:

Run the RF AC3 output from the LaserDisc player to one of those outboard surround sound processors (the kind you would match with a "Dolby Digital Ready" receiver before DD became common place). Those processors have line-out jacks for every channel in the Dolby Digital stream, I think. Then one channel at a time, you run the output of a channel (or two at a time since you have a stereo input on your soundcard) to the soundcard inputs and you record the entire soundtrack of the movie for that channel to the harddrive. You'd use a simple Windows Recorder type thing that can handle large file sizes. You repeat the process for evey channel (keeping your recording input levels the same in order to keep the relative volume for each channel balanced). You will then have six mono WAV files on your PC (one for each channel). If you brought in two channels at a time, you'll have 3 stereo WAVs. Split those out into unique mono files if necessary using a sound editing program like Sound Forge.

Now, this part requires a program called "Soft Encode" by Sonic Foundry or the equivalent. I've never used the thing, but if I understand it correctly, this program will take your 6 different mono WAVs and re-mix them back into a single AC3 file suitable for use in DVD authoring programs.

The real challenge will be making sure the 6 channels are in sync.

How's this sound?

I don't have the surround processor. I'm an amateur remixer and I'd know what I was doing... I'm willing to do the hard work to try it out and share my findings... just need someone to loan me one of them surround processors.

[borghe]

Just wondering if anyone else has found an answer. As far as I can tell, the only answer seems to be as above. I know no matter what I will need to run the LD player to an AC-3 RF Demodulator, but it would be nice if there was a way to transport that AC-3 signal directly to the computer then without having to first decode it to an analog signal and then outputting it to 3 wavs (front stereo, rear stereo, LFE mono). Any thoughts?

[e.lectronick]

Well, I'd be interested if the method mentioned a while back works.
The way I understood it was to record the raw digital bitstream using a soundcard that would allow "bit accurate sampling" with no change in gain or anything, saving the file as a .raw or .wav file then going into the folder in which it was saved and simply renaming the file .ac3
It would seem to be deceptively simple. Too simple for it to actually be correct, possibly. But as I am not sure what soundcards would allow digital sampling bit for bit with no alteration, I can't test it out.

However, if anyone knows of a good soundcard that does this, I'll pick one up and try it out. I've got nothing but time, and all the right equipment to experiment with.

-Erik.

P.S. I don't really like the aforementioned technique of converting to analog then back again, as this would degrade the sound a bit, and the ideal solution would be to keep the signal in the digital realm.

[borghe]

that wouldn't work. the track on the laserdisc if an RF modulated signal. the modulation of the signal is not at all digital. the signal needs to be remodulated to become digital again.

I had thought about the possibility of outputting the analog signal from the analog outputs and capturing that with a sound card, then looking if maybe a program had been written to do the conversion on the file. After looking if someone had created a program to do that I realised no program had been written because of the problems with it. Most likely vital information would either get lost outside of the frquency range of the outputs or inputs of the sound card, something would get messed up during the ADC of the signal, or just from loss on the outputs.

It looks like the only way outside of professional euipment that can transport an AC-3 signal across a s/pdif is to first convert the signal to 5.1 analog, and then record those analog signals and send them back to AC-3.

[e.lectronick]

"that wouldn't work. the track on the laserdisc if an RF modulated signal. the modulation of the signal is not at all digital. the signal needs to be remodulated to become digital again."

Yep, I get that. I should've been clearer. What I meant was to take the demodulated signal from the RF converter output (this *would* be digital) and record it straight into a S/PDIF input on a soundcard that can sample the signal bit for bit. There was another thread somewhere on this board where a few people suggested that it might be possible to then rename the file as an ac3 file and use it. Assuming the bitstream was recorded exactly as it was played out of the demodulator, it should work. I believe it to be a possibility, now moreso as I'm writing this. The only problem would be finding a soundcard that doesn't alter the incoming digital bitstream in any way. Unfotunately, many soundcards alter the signal by converting the incoming digital signal to analog to allow for an input gain stage in the audio path, then converting back to digital before anything else happens. When that happens, it's anyones guess how the resampling is performed by the card. Every manufacturer has their own way of doing things, and I'm sure very few of them had the preservation of an ac3 signal in mind when they designed their AD and DA converters.
-Erik.

[VidGuy]

I've been looking around at this for a while, and from what I understand, you're last method comes close. The issue is that what you really get (again, this is from other forums and whatnot, not personal experience) is a digital stream that has some small amount of real data, and then padding, then a small amount of real data, then padding.

I once saw a program that would take that stream and strip the padding out, creating a valid .ac3 file. I just don't remember where I saw it anymore.

[e.lectronick]

Vidguy,
Interesting. Are you saying that an ordinary PCM file format that had recorded an ac3 bitstream needs to be stripped of it's extra "padding" and that the original ac3 file is contained within?
If this is what you mean, I was under the impression that ac3 used a compression algorithm to cram 5.1 channels of audio into the same space as an ordinary stereo PCM file. There wouldn't be any excess padding to speak of unless you'd be stripping away extra channels.
Upon reading what I've just written, I guess that's not what you mean.
Please explain in greater detail...
-ERik.

[VidGuy]

I'm by no means an expert, but this is what I've gleaned across several forums -
AC3 is just a digital representation of a compressed file. It consists of packets of data spread out over time (i.e. it is "packetized" to be able to be transported with the mpeg in a DVD or laserdisc, each packet representing an amount of time for the next "n" milliseconds - don't know exactly what "n" is). The appropriate decoder knows how to decode the packet back into sound. If you just take the bits off of the wire (the S/PDIF input, presumably), you can store them into a file - they're still just bits. The only difference is that when they're stored with mpeg, they have a timestamp - when they're played, they don't. Since they don't have a timestamp when they're played - you need to send "padding". Because the bits are compressed, when you decompress them - it will take longer to play than it took to send them on the wire - so the padding is inserted just to keep pace.


So you need to write some kind of program to remove the padding, since you don't want the padding to go into the AC3 stream of your DVD.

As a disclaimer - this could be total B.S. - I intend to play with this some day, but have not yet had the time to do so......

[e.lectronick]

Vidguy,

Hm. Thanks, that explains some things I didn't know. I imagine there must be programmer types out there who know how the algorithms send/store these packets of info and could write a simple program to deal with recording and storing an AC3 file properly. However, since I don't have that kind of training -I'm an audio engineer (misnomer since the profession is actually a technician's job, and we aren't really engineers)- I think perhaps we could tackle the problem from another angle:
*Hardware*
Assuming the processors used to decode the AC3 signal into PCM data aren't embedded on the same chip as the Digital to Analog converters, it should be possible to splice into a converter box somewhere after the decoding process is done, and prior to the conversion of the signal back into the analog realm. Then it would simpy be a matter of sending the digital PCM stream to a digital input for recording as a regular 5.1 PCM signal. I could be oversimplifiying it a great deal -this is just off the top of my head- but I understand the basics of Pulse Code Modulation, and it's really pretty simple stuff when you get down to it. People build their own D to A and A to D converters all the time with off the shelf parts, so I wonder how difficult it would be to jerry rig a couple of wires to bypass those converters in a decoder box and run them into a digital input?
-Erik