Film-Tech Forum ARCHIVE: Digi-Beta connections.

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Posted by Stephen Furley (Member # 1277) on 04-15-2014, 07:27 PM:

There is a possibility that I may need to run something on Digi-Beta in a few months time. I assume that the video output would be SDI; would a basic playback only deck have a separate digital audio output, or only embedded audio? If so, would this be AES/EBU balanced or AES3id co-ax?

Posted by Scott Norwood (Member # 30) on 04-15-2014, 08:12 PM:

A regular D-cinema projector will not take SD-SDI. You need to upconvert this to HD-SDI, either with a scaler or converter box or an HDCAM deck that also plays Digi-Beta (e.g. HDW-M2000/20, HDW-D1800). Or you could convert the SD-SDI to DVI.

For Digi-Beta decks, the J30SDI will only give AES embedded audio. The component version of the J30 has no digital audio (or video) output capability at all, so don't get that one. The DVW-A500 has AES output on balanced XLR connectors. The HDW-D1800 has AES on BNC connectors. I don't remember about the HDW-M2000.

With the upconverting HDCAM decks, look for menu option 950, which lets you select how the SD signal is to be upconverted--it can be shown as 4x3 pillarboxed in the 16x9 frame, 1.78 cropped (if the original tape is letterboxed), and 1.78 unsqueezed (if the original tape is anamorphic).

Neutrik and others make little converters that let you easily convert AES from balanced XLR to coax BNC.

Posted by Carsten Kurz (Member # 5396) on 04-16-2014, 03:55 AM:

Hmm, all current DLP machines are quoted with SD-SDI input capabilities as well, e.g. 640/480 or 720/525 at all common progressive and interlaced frame rates.

Depends on wether there will be some time for testing beforehand.
Even with Digibeta, a scaler is still preferable though.

- Carsten

Posted by Stephen Furley (Member # 1277) on 04-16-2014, 04:11 AM:

Scott, let me explain what this is about. I received an e-mail yesterday evening asking if the cinema could screen Digi-Beta. My reply was that we didn't have a player, and we're never likely to given the price of the things, but if somebody wanted to provide one for a show we could probably get it on screen. Hire rates for the most basic playback only models seem to start at about 80 pounds per day, plus 20% VAT, so that would be affordable. We certainly couldn't buy one, we might just about be able to afford a secondhand VHS! Also, I can't imagine that there's much being produced today that might possibly be shown in a cinema that is being shot in SD, so any need for one is likely to be extremely infrequent.

SD-SDI should not be a problem, I have a box which can convert any form of SDI, up to 3G, to HDMI and I can put that into the DVI input on the Cine-IPM. I've done this in the past, and it works. I don't have a SDI de-embedder however, so embedded audio only would be a problem. I have the matching balun transformers to convert both ways between the two flavours of AES, so that wouldn't be a problem either, but if needed then I'd need to look them out; I haven't used them for several years.

I briefly spoke to the person who asked the question last night. He's hoping that it this, whatever 'this' may be, comes off then he can get it in some other format, but if it is only available in Digi-Beta then it should be possible. Do you know what the most basic playback only model which does provide AES output in either form is?

If something isn't available as a proper DCP then my own preference is generally to run it on a laptop. I know a lot of people don't like this, but I've never had any problems with it. Laptops are cheap, so you don't have to hire them, they're small and light, I have two, so I've got a backup, I've used them before so I know that they work with the equipment in the cinema and since I already have them I can test in advance if the file gets to me in time.

When we re-opened the cinema last month with 'Basically, Johnny Moped' the director, Fred Burns, offered us various formats, including Digi-Beta and HD-Cam. Digi-Beta seems strange, why would we want to use a SD format for something shot in HD? We opted for a file to play on a laptop and it ran fine. I had to use the new laptop as the file was 100 GB for 77 minutes, I think it played at about 170 Mb/s, and the processor in the old laptop just couldn't keep up with it. We did have a MPEG4 copy running on something else as a backup, but it was't needed. The only problem with playing from laptops which I've seen at several festivals is things unexpectedly popping up on screen, but that's not difficult to avoid if you set it up properly.

Anyway, it looks like we should be able to do this, without it being too expensive, if we need to. I'll be seeing him at a meeting this evening to discuss programming for July, I'll ask him what he's thinking of screening.

Posted by Scott Norwood (Member # 30) on 04-16-2014, 05:04 AM:

The only decks that I know of that have AES output are the full-size models. The J30SDI is the "cheap" (read: "not cheap") playback model, but it only has embedded SDI and analog (two channels only) audio output. If you can't take analog audio, then I would just rent an SDI disembedder as well, which should not be terribly expensive.

My experience (mostly with the Christie machines) has been that, for some reason, SD resolutions are supported on DVI, but not SDI.

And, yes, I agree that showing anything other than archive material in SD in 2014 is madness....

Posted by Steve Guttag (Member # 268) on 04-16-2014, 06:13 AM:

Scott...I'll check the next time I have the opportunity...but I'm pretty sure one can get an SD-SDI to work on most any DCinema projector. You've definitely got me curious...though it has not come up for us in a long time. Most sites that we have that handle SD sources typically have a scaler in there anyway to deal with the various formatting that is done to SD sources (including DVDs).

Posted by Pete Naples (Member # 761) on 04-16-2014, 07:24 AM:

Echoes my experience Steve. I don't remember it being a problem, but like you anywhere that did it has a scaler. Nowadays we're encouraging the capture of video formats for DCP creation.

Point of fact one of my sites in Edinburgh has a purpose built capture rack, with a Clipster installed. They got some column inches in Cinema Technology about it.

Posted by Stephen Furley (Member # 1277) on 04-16-2014, 08:03 AM:

Thanks for the info. With any luck, if it does happen there might be a DCP available of it by then. If we do have to run it on Digi-Beta then I doubt that it would have more than two channels, possibly matrixed, so we could use analogue, and therefore the cheaper machine.

Posted by Geoff Newitt (Member # 6663) on 04-16-2014, 08:38 AM:

We do - or used to do - quite a lot of screenings from DigiBeta. It's a surprisingly popular format for festival-type films. I guess because it was fairly widely adopted.

PAL DigiBeta looks surprisingly good; I only ever saw one NTSC tape and that didn't look so hot.

I think all bar one of the decks we own are the component model, and we've never invested in a de-embedder to extract audio from SDI. So far, everyone's been happy with two of the analogue audio outputs matrixed. In fact, most tapes I've seen have two tracks as Lt/Rt (often 'stereo mix' in video jargon) and two as a hard stereo 2.0, you can select which pair to 'monitor' and adjust the gain with the headphone volume control, if memory serves. (I'm talking about the J-3, J-30, J-30S.)

And we've always used a scaler, even for our solitary J-30S.

For films supplied as computer files, I can recommend DCP-o-matic (there's a thread on here somewhere about it) - and not just because its author Carl is a former employee of ours. A number of Picturehouses use it, and it's quite user friendly. It works best if you have plenty of time and/or access to lots of computer power as it can be a little slow.

Posted by Leo Enticknap (Member # 534) on 04-16-2014, 09:52 AM:

quote: Geoff Newitt
It's a surprisingly popular format for festival-type films. I guess because it was fairly widely adopted.

It was the standard recording and editing format for standard def broadcast TV applications from the mid '90s through to the late-00s, and so there are still a lot of tapes about. However, even though it is now essentially obsolete, decks were never made in vast quantities, the volume of media in circulation and needing to be migrated for archival preservation is still big, and therefore VTRs remain in demand and thus expensive to buy - even second hand and with high head hours.

I'm guessing that the show which Stephen might have coming up is of a high-end TV show or low to medium-end feature film or indie documentary type thing made during the '00s, for which a digibeta will have been made at the end of the post-production process for festival screenings, pitching to DVD publishers, etc. etc. Even at the little theatre I ran at the University of Leeds, we'd get two or three such shows a year. Since the department I worked in owned a deck, we would normally capture it to a high bitrate H.264 file if we could get our hands on the tape ahead of time and show it from a PC in the booth we'd made up specifically for playing DVDs, BDs (it contained three optical drives with different region combinations) and files. If not, we put the VTR in the booth and used component (analogue) video out.

Digibeta is an annoying combination of an obsolete format that refuses to die totally, and one for which VTRs remain stubbornly expensive.

Posted by Bill Gabel (Member # 1105) on 04-16-2014, 10:15 AM:

We would do around one to two digibeta screenings for clients for press screenings here in New York for a year. Most everyone moved up to HD-CAM for tape screenings for press & festivals with the big studios using HD-CAM SR and D-5 formats. With the digibeta shows we just used the standard analog stereo or Lt/Rt signal to a mixer and then to the Dolby processor.

Posted by Scott Norwood (Member # 30) on 04-16-2014, 10:17 AM:

Steve (or anyone else): if you can figure out how to make this work, let us know. It never worked for me, but I have not spent a huge amount of time trying to make it work, either.

quote: Geoff Newitt
select which pair to 'monitor' and adjust the gain with the headphone volume control

Adjustment of the output level requires setting menu option 114 to "VAR" on the J30. I have used this in the past when the sound is recorded too loud on the tape--even if it does not quite clip, the analog outputs of these decks can distort at high levels. Setting this menu option and setting the headphone volume knob to about 10-11 o'clock fixes this. On the full-size decks, the analog output seems to be of higher quality; if needed, there are knobs that can be popped out and used to adjust the output levels.

Posted by Antti Nayha (Member # 4980) on 04-16-2014, 10:26 AM:

An important note if you're using the analog XLR outputs of the J-3 or J-30: those are monitor outputs that are set by default to boost the output level by a few dB. In other words, if you're playing an improperly mastered tape without proper headroom, peaks will be horribly distorted.

You can circumvent this by settings the menu item 114 ("Audio monitor output level") to VAR and turning the headphone volume knob to an appropriate position. Since there's no display to show the current amount of boost, just set it rather too low than too high, and then compensate the volume loss on your mixer / sound processor.

Posted by Stephen Furley (Member # 1277) on 04-17-2014, 04:52 AM:

It's some sort of film of a music festival. I'm hoping that if they do decide to screen it they can get it in some other format. Apart from anything else when you've only got 68 seats to sell the cost of renting a player is quite considerable, but at least I know that we can do it on Digi-Beta if we need to.