Laserdisc capture - general thread

[pipefan413]

For CLV discs the RPM is highest at the start of a side, which is generally when the player is at it's noisiest vibration wise. As the side progresses the the RPM decreases to the point where the player is silent but for the whoosh of air as it spins. If the rumble on the audio is consistent for the duration of the capture then you can probably rule out the player as the source of noise

Yeah, but that's just it, I don't think it is consistent from start to finish: it's *really* obvious at the very beginning (check those samples and you'll see what I mean) and it's completely different in the different captures, depending on the player. But some version of it is there, even on the Runco cap.

If it was just the same noise to varying degrees then I'd be more likely to blame the disc rather than the player, but it isn't. It's four completely different sounding "signature" noise profiles that differ depending on the player that's being recorded. You get one rumble (which is actually more like a hum) from one player, one really really loud rumble from another, and a slightly more muted rumble from another, with the Runco sounding somewhere in between two of mine (a little closer to the smooth hum but still with very apparent repeating rumble pattern that sounds like the disc spin vibrating the chassis).

I'm also hearing relatively frequent clicks in all of the captures, mine and the one from the Runco. I don't know if that can really be fixed, unless perhaps *that* is from dirt/scratches/rot (but since it seems not to occur in the exact same places I'm not totally convinced that it is). First off, the only way to capture in sync on my end is to capture from my video capture card, which is PCIe, unshielded, and therefore inside my PC case amongst a bunch of other electrical components not too far from the PSU. If I surrender my obsession with avoiding sync drift and capture from something else, it doesn't seem to fix that though: even when I use an external capture device (e.g. the ESI U24 XL or an older audio interface I have from my years as a musician) this is apparent, possibly because those are USB powered devices, possibly because it's inherent in the source. The clicks don't seem to occur in precisely the same way on every capture but they do happen on every capture. At one point I wondered if possibly those were a sign of resampling, perhaps done by the capture card in an attempt to keep sync, but I think I've abandoned that supposition now that I know it happens regardless of which device I use to record. Maybe it's some specific form of EMI that manifests as clicking rather than a hum/buzz. Maybe it's something else to do with my PC and I should try disabling everything related to networking while recording (even ethernet stuff) to see if that does anything whatsoever.

I think my standards might simply be unreasonably high for this stuff and need adjusting to the reality of the situation. That would be a bit sad but it wouldn't surprise me. I was hoping to help archive the closest thing to "definitive" analogue recordings for some of these films but it might be that they're all going to sound pretty crap because of various limitations of the LaserDisc format and the recording devices I'm able to use.

[zoidberg]

The clicks and such are dirt, scratches and dropouts. How they are handled will vary from player to player but without the noise reduction CX encoding offers they will be there to some extent as will the surface/background noise. Cleaning a dirty disc will help as will a scratch-free surface. But what's in the pits themselves essentially defines the sound

As for different players sounding different, things like calibration/alignment will play a part as will the design of the player itself (ie components used, ageing components such as dry/leaking capacitors, shielding of power supplies etc). Once digital tracks were introduced the FM analogue tracks were basically 'legacy' tracks for those older players which lacked the ability to play the digital tracks, the bandwidth couldn't be reassigned so the analogue tracks stayed. Thankfully as a result we got AC-3 and commentary/isolated tracks. If a disc is particularly rotted the digital track can sound awful (as the error compensation starts to fail) but the analogue tracks will suffer less, assuming the disc plays at all.

I've read that once digital tracks became the norm on LDs the analogue tracks became less of a priority to player manufacturers. As most people would want to listen to the PCM track even if using the analogue RCA outs, unless you were importing LDs with dual language (or were in the unlikely position of wanting to listen to a DTS LD without a decoder) you'd probably never play a stereo analogue track, but if you did the CX encoding would make it sound pretty decent. Supposedly the best players for analogue sound quality are the early gas-laser models.

[captainsolo]

That jibes with what I've heard. I think the analog on my lx-900 is the best I have but my player has issues with it's analog outputs.
When I start capturing I don't know what will be best for analog captures but my focus is digital PCM anyways. There shouldn't be player differences on digital tracks should there? I was thinking of using my minty backup player just for pcm capturing: dvl-700.

[pipefan413]

That jibes with what I've heard. I think the analog on my lx-900 is the best I have but my player has issues with it's analog outputs.
When I start capturing I don't know what will be best for analog captures but my focus is digital PCM anyways. There shouldn't be player differences on digital tracks should there? I was thinking of using my minty backup player just for pcm capturing: dvl-700.

Nah, theoretically zero difference with PCM if you set up for bit-perfect capture, but if you have more than one player it might be worth experimenting a bit. I have 3 and have checked that all 3 capture the same data regardless, but I've noticed small differences in each one's ability to capture the start/end of a side, things like that. The actual raw data however is the same, apart from the odd tiny variation usually at the start and/or end (when more often than not, it's just "silence" anyway).

[zoidberg]

Any LD player capable of digital-out should be adequate for bit-perfect capture, provided it's in good working order. A weak RF signal from the laser or failing caps can degrade the PCM audio (for some reason it's the first thing to go, before analogue audio and video itself), if in doubt, run a DTS disc, if it plays perfectly then you're good

[captainsolo]

Any LD player capable of digital-out should be adequate for bit-perfect capture, provided it's in good working order. A weak RF signal from the laser or failing caps can degrade the PCM audio (for some reason it's the first thing to go, before analogue audio and video itself), if in doubt, run a DTS disc, if it plays perfectly then you're good

I experienced all of those signals when starting out on players firsthand.

[captainsolo]

So I've got my dvl-700 setup on my desk connected via the U24xl and have checked the signals work. Audacity picks it up and I was able to do a test recording with no problems. I take it I'll need to get reaper to do bitperfect captures. I've never used the software before so is there anything I should know about implementing all of this the first time and trying to get all the sound setting correct?

Just to make sure the side starts are good I'll do a plain extra cap of each Side 2 start to ensure the autoflip process didn't cut anything.

[pipefan413]

I'm having all sorts of headaches suddenly with captures on the same hardware I've been using for months now and it's getting on my nerves. A long time ago I found that sometimes I'd run a capture and it would have the (analogue) audio totally out of sync for no clear reason, usually accompanied by a visible lag in the timestamp / playback timer at the start of the capture. It'd be running smoothly on a black screen and then as soon as the frames of video start coming in, it freezes, and starts recording but with the video noticeably later than the audio. This is now happening with irritating frequency.

The player I'm currently recording from is the Pioneer CLD-1750 that has been my more or less preferred player overall for some time. The capture card is a Blackmagic Design Decklink Studio 2, recording the player's composite output.

When I had issues like this before it seemed to be fixed by rolling back to an older driver for the Decklink. It's still on that same old version and hasn't updated so I'm wondering if maybe either...

1. Windows has updated something in the OS that has broken the functionality of the older driver, or
2. The CLD-1750 has started to develop intermittent problems with sync for some reason which apparently are increasingly frequent

I can't really keep re-running captures over and over again until I get one that's synced properly but I also can't monitor the output as it's recording through a CRT or whatever because the player only has 1 set of outputs (unlike my CLD-S350, but that player also has noticeably worse analogue audio and I don't think the picture is quite as good as the CLD-1750 either, though it's very similar). I guess I'll switch to capturing the S350 for a while for anything that I don't need high quality analogue audio from, and see if the problem reappears on that player. I dunno if anybody else on here uses the Decklink Studio 2 for captures but I figure it's worth documenting just in case anyone else is having the same issues all of a sudden.

[zoidberg]

Sorry to hear you're having problems. The player shouldn't be out of sync as it's analogue, the audio/video are interwoven with one another (actually they occupy different bandwidth spaces within the RF signal) and the laser can physically only be at one spot on the disc at any given time. If you're using VDub there's a little box to tick which says something like 'resample audio to maintain sync', if I don't tick that the audio and video will drift off slowly as the capture progresses. Likewise if I enable audio playback during capture it drops frames.

A long shot maybe but is your HDD full, or getting full? It may benefit from a defrag. Otherwise it's probably what you suspect, the driver update has broken something. I've had to keep my old Win7 PC purely for LD caps as driver support for the video card stopped after Win7 and I am too lazy to find a different card which works as well.

[pipefan413]

Sorry to hear you're having problems. The player shouldn't be out of sync as it's analogue, the audio/video are interwoven with one another (actually they occupy different bandwidth spaces within the RF signal) and the laser can physically only be at one spot on the disc at any given time. If you're using VDub there's a little box to tick which says something like 'resample audio to maintain sync', if I don't tick that the audio and video will drift off slowly as the capture progresses. Likewise if I enable audio playback during capture it drops frames.

I've been capturing in the Blackmagic Desktop Video software because when I was using AmaRecTV sync was drifting (and was limited to 16-bit audio, whereas it's 20-bit in Desktop Video, being first party software for an SDI card). It doesn't have any settings pertaining to sync, it just usually gets it about right except from when it suddenly doesn't. I checked and the driver is still the old driver version but aye as I said it could just be that Windows changed something I suppose. However, I did a fresh capture from a different player and it worked perfectly, so I'm again wondering if something's up with the player, somehow. But yes, clearly the laser has to be picking up the signals simultaneously, so that'd be a bit odd... I dunno, I just know it's irritating the hell outta me hahah.

Sync doesn't drift, it remains at a constant rate because it's using the clock rate off the capture card, but the trouble is that it's offset: video falls later than the audio, quite significantly sometimes. It definitely seems to vary depending on what player I'm capturing from but I've no idea why that'd be. And closing and reopening the Desktop Video application often fixes it, which makes something about the capture process seem flakey to me.

A long shot maybe but is your HDD full, or getting full? It may benefit from a defrag. Otherwise it's probably what you suspect, the driver update has broken something. I've had to keep my old Win7 PC purely for LD caps as driver support for the video card stopped after Win7 and I am too lazy to find a different card which works as well.

It isn't but I suppose it has been. As in the drive was more or less full then I moved stuff off it. I guess it could be that it is fragmented although then I'd expect more general latency rather than a misalignment of video and audio; it seems like it's during capture rather than just when writing to disk since the audio monitors in real time and I can sometimes tell that the audio is way ahead because there'll be a loud bang or something in the film and I'll see the audio almost peak before I see the thing in the video capture that caused the noise, if that makes sense.