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D-VHS Interchange  

post #1 of 24
Thread Starter 
We recently encoded an HD sports program and loaded the file onto a Panasonic PV-HD1000 D-VHS recorder for a customer. The tape was played back on three different Panasonic vtr's to assure that we made a stable recording.

The client owns a new JVC machine unfamiliar to me but listed as a D-VHS vtr.

When the client attempted to play our tapes there were lots of problems with blocking and freezes.

Years ago, there were video recorder formats where interchange of tapes among like model machines was not guraranteed. I suspect just because someone says a deck is D-VHS doesn't mean it adheres to any technical standard that I could find.

Has anyone had experience playing known good HDTV D-VHS recordings made on a Pansonic PV-HD1000 on one of these newer models?

Experiences with VHS/SVHS tapes across these models don't count because all of these vtr's will interchange analog VHS tapes without trouble.

post #2 of 24

I see you made your way down here, too.

I have two PV-HD1000s but have never tried to play back anything recorded on them to other D-VHS machines.

Gary Merson says somewhere else on this forum that he was able to play back D-VHS tapes from a PV-HD1000 into a new Sony integrated flat-screen 4x3 DTV (can't remember the model) through the Firewire jack, but he could not record from the Sony to the Panasonic.

BTW, I don't use the Panasonic or Maxell D-VHS tapes - too expensive. I buy 1-hour, 2-hour, or 3-hour Maxell ST-series S-VHS tapes from Tape Warehouse in Virginia Beach and they work just fine.

The ST-62BQ is about $6 each in lots of ten, the ST-126BQ is about $7.50, and the ST-182BQ is just under $10 in lots of ten.

post #3 of 24
Thread Starter 

I'm pretty sure it's not a tape stock issue. I think that short of having a SMPTE or EIAJ standard, it's a free for all right now. We are trying to find one of the JVC models. I might ask the client to send me one so we can figure what's going on. This one caught us by surprise. The client told us there was no obvious way to record HD with that JVC model. We have plenty of HD1000 units for present needs and have never had a DTV interchange problem with any of them. Even the off tape pre-limiter RF envelope looks real flat between machines.
post #4 of 24
Originally posted by John J. Turner
The client told us there was no obvious way to record HD with that JVC model.
If you're talking about the HM-DH30000(w or w/o the U), there have been people in these forums (gridleak among them) who've had some success recording from the discontinued Panasonic TU-DST50/51 DBS STBs. The only recent shipping thing that you could record from using them is Sony's cable STB, being deployed in the NYC area by Cablevision. There was some hope that you could record from the tuner in Sony's new 1394/DTCP connector equiped sets, but that turns out to be untrue. We now hope that you can record from the tuner in Mitsubishi's 2002 Integrated sets, though no one is sure (or at least not anyone who's talking *cough*Gary-Merson-who's-been-testing-the-sets-for-a-print-review*cough* :)).

-- Mike Scott
post #5 of 24
Originally posted by John J. Turner
Has anyone had experience playing known good HDTV D-VHS recordings made on a Pansonic PV-HD1000 on one of these newer models?
I have 5 good HD1000's and 2 new JVC DH30000's, and a fair amount of experience with these machines. All the HD1000's are capable of reading each others tapes flawlessly, but the JVC machines can only read tapes from my 3 best HD1000's (one brand new, and two with new heads). The same holds true in the other direction: not all the HD1000's can read perfectly the tapes made on the JVC's.

I have an old Panasonic Demo Tape that came with the "demo" HD1000's used by retailers for non-stop demonstration of DVHS. That tape has hundreds of hours on it (maybe thousands), and it still plays perfectly in most of my HD1000's. It will not play at all in the JVC's.

Obviously there are slight differences, probably mechanical, between the two. It's not, however, the tracking offset, because a standard VHS alignment tape is used to set the offset in the Panny's (for both digital and analog).

On other matters: the firewire connection between the HD1000 and the DH30000 works very well (because the HD1000 is simple minded and nondiscriminating), and dubbing can occur in either direction. The JVC does not work easily with the Panny STB's, as noted in other threads here. It seems to be a 1394/5C problem.

Your comment about loading an mpeg program onto the HD1000 is quite interesting to me. Could you enlighten us on the equipment and software used? Is it in the price range of rabid HDTV hobbyists?

Lastly, what would you charge to make a DVHS test pattern tape?
post #6 of 24
Oh Yes! A test pattern tape would be wonderful. I'll pitch in some $ for this.

post #7 of 24
Originally posted by gridleak
I have 5 good HD1000's and 2 new JVC DH30000's
Jeez, Roger, that's some serious fetish you got going on there :).
...rabid HDTV hobbyists?
You got that right!

-- Mike Scott
post #8 of 24
Some time ago, a comment was posted about the difference between 'standard' and 'demo' D-VHS machines. I seem to recall that the 'demo' units will only display '1-1' as the channel ID on a particular recording, while 'standard' units will show the correct channel number.

I have noticed that if a station is not transmitting PSIP correctly, the recording will show 'D-VHS 1-1" anyway. However, changing channels and recording from another station with bring up the correct channel ID, like '3-1' for KYW, or '6-1' for WPVI.

Any other differences? I seem to recall comments made about the bias on the record and playback heads.

BTW, if you want to dub from one machine to another and monitor what you are dubbing, I have tested a useful little Firewire hub made by Kramer Electronics (no price on it yet) that lets you do exactly that.

Wired the right way, you can dub from one machine to another and watch what you are dubbing. Both machines must be set to "dVHS" on the channel selector. The tuner in use (either TU-DST50W or TU-DST51A) will only recognize and talk to one of the VCRs, but the MPEG stream can easily be recorded over.

Kramer is not shipping this product yet, but when they do, I will post price and availability info. It's a small box with outboard wall wort power supply and works great.

I also retired the Panasonic-supplied Firewire cables (too flimsy and pull out easily) with versions sold by Bi-Tronics in Hawthorne, NY. They are 10' long, cost about $20 each, and stay put when inserted into the 1394 connector.

post #9 of 24
I'm not sure if the channel number problem is solely related to demo machines. I have one demo that reports OTA channels properly but reports output from the Dish modulator on channel 3 as 1-1. Another machine reports the channel properly as 3-1. Solving the problem might take more time than it's worth.

The use of hubs with the Panny machines was covered in considerable detail earlier this year in this thread.
post #10 of 24
Thread Starter 
I'm glad the D-VHS demo taps are still playing, we encoded the content for Panasonic. The comment about them not playing at all on other machines reinforces my suspicion that while the RF tracking may be compatible between machines, the method of encapsulating the transport stream may not be standardized.

The equipment needed to create the tapes from either a test generator, HD-D5 or HDcam tape is formidable. Don't expect it to be affordable to a hobbyist for a long time.

Here's how we do it.

First, we receive content on an HD tape format, sometimes with a second tape (DA-98) with surround audio. Frequently the tapes need minor editing to add lead in/out black. Recently we have seen an expanding use of Dolby "E" data which can put 8 channels of audio on two channels of an unmodified HD-D5 vtr.

One of our broadcast ATSC encoders is set to the desired stream rate. If we are creating a high quality file, the rate could be set as high as 80 Mbps and 4:2:2 sampling. For D-VHS and Sencore 995/996 players, we set the encoders to ATSC rates and 4:2:0 sampling. The AC-3 encoder is set to 384k which is not mandatory but is what most stations have selected as a normal operating value. This rate is the minimum that will support 3/2L (5.1) encoding. We can go down to 192K for 2/0 and up as high as 448k.

Once this is set, we "time" the program and create a null file in a high performance NT workstation using a variety of GUI based apps with DVB interfaces.

We then use a broadcast editing system to cue / run the playback vtr, start the workstation and record the stream from the encoder into the null file. Once this is done, we QC the file through an analyser to look for all types of errors.

Lastly, for D-VHS, we play the file through a broadcast 8VSB exciter (we use Harris and Zenith products), into the DST50 or 51 and thence into the D-VHS in record mode.

Some variations that we add include closed captions, second audio programs, SD/HD multiplexes and PSIP since the new Hughes designed box (Mits, Toshiba, Philips, Hughes) do not tune reliably without these tables.

It's very expensive! To do this reliably, you need multiples of all the listed equipment. I didn't even mention the "Glue"; sync generators, GPS clocks, switching, patching etc.

Pete Putman has asked me for a D-VHS test tape. If we can get a consensus on the types of signals that would be useful to everyone, I'll make a master D-VHS tape. I just don't want to do this creation task a hundred times.

Since gridleak has all the decks maybe we can volunteer him to make dubs.

The comments about the channel number display are related to the presence or absence of PSIP. It is NOT required by FCC rules at present for broadcast. The Dish 5000 remod does not create PSIP. (That process costs about $30,000.00) In fact the HD streams off Echostar III are DVB streams. In the case of WCBS-DT, the Echostar stream only includes the elementary audio and video pids.

post #11 of 24

Since gridleak has all the decks maybe we can volunteer him to make dubs.

If you start making dubs, I would love to have one. Please let me know if you want to sell me one at sedit@wanadoo.fr.

post #12 of 24
John Turner,

Thanks for your helpful information!

A D-VHS, HD test pattern test tape is really needed.
You can count me in to help make dubs for others.

post #13 of 24

Thank you for your excellent description of the process of producing DVHS tape. That last step was a bit daunting. They don't seem to stock Harris CD-1A's over at Fry's.:) I had hoped, of course, that the last step was direct from server to recorder via 1394.

Thank you again for your offer to make a test tape. I will be more than happy to do the dubbing. Contact me if there are details you wish to discuss. Meanwhile I will think about the patterns I would like and post that here shortly. Others who want a tape should do likewise.
post #14 of 24
Same patterns as Avia would be great. Also a sequence of IRE window patterns switching from 30 to 70, 20 to 80 and 20 to 50 to 80 for gray scale calibrations would also be helpful.

post #15 of 24
There are tapes from maxell, JVC, and panasonic. Is there any visual difference when recording on these? The panasonics are a couple of $'s cheaper.
post #16 of 24
Thread Starter 
We have used all of those tape types and haven't seen any difference, at least over a few playback cycles. This is a digital recording, it behaves similarly to the way a floppy disk copies a file - ie perfect or useless.

The difference would be noticeable after playing the tapes many times. We provided D-VHS for a NY museum who found that Panasonic St300 tape life was about 3 months with continuous 10hr/7day playback.

The D-VHS tape failure appearance is quite different from analog VHS. The playback would look and sound normal until the end of life and quite sudddenly image feeezes and blocks will appear.

Lab class test equipment could give some idea of tape condition but the cost would be prohibitive to the average user.
post #17 of 24
Originally posted by John J. Turner
We provided D-VHS for a NY museum who found that Panasonic St300 tape life was about 3 months with continuous 10hr/7day playback.
That's about 400 plays per tape. I've got a some JVC DF-480 tapes with 200 plays that are still ok, but no other "longevity" experience. I have a sense that JVC tapes work better than Panasonic on machines with worn heads. No hard evidence though. If we're discussing this in connection with the test pattern tape I would suggest JVC DF-300, but I'll be happy to use a variety of different brands so that everybody's happy.

Originally posted by jrichards
Same patterns as Avia would be great. Also a sequence of IRE window patterns switching from 30 to 70, 20 to 80 and 20 to 50 to 80 for gray scale calibrations would also be helpful.
John's going to run for the hills if we ask for that much. I'd be happy with some sweeps, pluge, and grayscale. Shouldn't we be considering only patterns needed after the basic alignment, convergence, etc, has been done using the Avia DVD?
post #18 of 24
Thread Starter 
What I will probably do is start assembling a HD-D5 master with the test sequences and ask Pete Putman to come over and check it. Once that is done it's simple to encode and copy to tape.

Roger, btw, now I know where the drip pan is.
post #19 of 24
Not exactly DVHS, but I did supply a good assortment of 1080i test signals on HiPix format a few months ago. I uploaded them to a members FTP site in native size (that is 19.3mbs HiPix Files) Many members sucessfully compressed them using simple PC compression utilities.

I can set this up again if anyone is interested and has an FTP site.
post #20 of 24
You can send it here. I will put it on my FTP or my web server. email me if that will work.

post #21 of 24
I would love to get a "test" tape for HD1000 ! Count me in.


post #22 of 24
If not too late, I would like to suggest a brief test signal for the audio as well, since no one mentioned it before.

Like to have DD5.1 and DD2.0 test stripes with tones on each channel to follow. These are the two main formats that most of us will be hearing from HDTV programming.

I'll be following and listening for the HDTV test tape availability.

John Turner- Thanks for that explanation of the process. I enjoyed reading it.
post #23 of 24
Just a gentle reminder John. A test tape would sure be a nice Christmas present for all us HD crazies around here. Let me know when so I can order extra tape and warm up the machines.:cool:
post #24 of 24
Like everyone else, I've been wanting a DVHS test tape every since I got my HD1000 player.

Please count me in!

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