Hdv playback with normal dv deck?

[Barry Green]

Ignacio brings up a good point -- if the DV deck is somehow also HDV-aware, then the possibility exists that you could do it.

But any deck designed before September 2003 is almost unquestionably not HDV-aware, as there *was* no HDV even announced until 9/2003.

If you put an HDV tape in one of today's DV decks, it will think the tape is blank. You will not be able to capture from it. It doesn't know there's anything on the tape. The deck would have to be made aware of how to understand HDV. Ignacio's saying that there may be a camera out there that can do it (the PC350). But it would have to be specially engineered to understand both formats (HDV and DV).

A regular DV deck will not play, nor be able to be used to capture from, an HDV tape.

[Ignacio Rodriguez]

> But it would have to be specially engineered to understand
> both formats (HDV and DV).

Yes. Since we are on to my my point, I would like to add --or rather insist on-- that it's probably very simple for Sony to add this capability to the firmware of any DV cam with a Firewire bus. So we should not expect to pay more for such a feature. Reading this, Sony?

[Heath McKnight]

Is it firmware or something more mechanical?

In 1994, I first heard about DVD players and they INSISTED there would be a small device to make CD players play DVDs. That was shot out of the water, obviously. And yes, I waited three years for DVDs (and then another year to afford a then-cheap $250 player).

Anyway, what I'm trying to say is, I wouldn't be surprised if it's more than just a firmware update, thought that would be nice! <g>

heath

[Toke Lahti]

Not "getting something out" from analog outputs doesn't nessesary mean the same than what you might be getting out through fw.

So many people says it can't be done, but how many has tried to capture hdv?

[Davi Dortas]

I have to laugh at already 18 replys to this thread. A simple "No" at start would have said everything. I can understand the question asked, it would made sense if you were transferring files on a computer, but tape mechanisms means the data has to be decoded.

[Ignacio Rodriguez]

Decoded?

There is a program that lets any Mac with Firewire use any DV deck as a data backup system. It's so cool. And of course you can play back the tapes on any DV Deck and see nothing. And NONE of those decks were designed for that. It's all just software magic. Not very different from what they did to pull off the MPEG-on-DV trick. So I don't want to settle for a "no" yet until somebody with a '350 or similar new generation DV deck tries it first. And I will be outraged if Sony attempts to charge more for decks that can do it.

[Heath McKnight]

Toke,

We've been telling you all along, it CAN'T be captured off a non-HDV deck, because it can't read the mpeg-2 TS stream. Why try something that will fail? Besides, I inadvertantly tried it when I hit HDV footage on a tape filled with mostly DV footage and it failed.

heath

[Barry Green]

Exactly. I've tried it from my deck -- IT DOESN'T WORK.

The deck has to know about the HDV format, it has to be able to read the data stream in order to put the data stream on the firewire port. It has to be able to read the data stream to extract the timecode. And DV decks don't know how to read HDV data streams.

What Ignacio is referring to, about using DV tapes as data backup, leaves out an important bit: (unless I don't understand it properly...) they packetize the backup data within DV data packets. So the data on the tape looks (to the deck) as if it's DV data, with DV headers, so the deck can properly read it. It's not just pure raw data.

If Sony or JVC make a deck that happens to be dual-purpose, then you could use that for HDV capture. But a straight DV deck will not work, it has to be specially engineered so that it also understands HDV data.

[Ignacio Rodriguez]

> they packetize the backup data within DV data packets.
> So the data on the tape looks (to the deck) as if it's DV data,
> with DV headers, so the deck can properly read it. It's not
> just pure raw data.

Yes. Conceded, that's probably the way it is done.

> Anyone can make decks to play HDV from ordinary DV decks
> but they dont want to. They want to make BIG money BIG
> money for you to buy there $3700 decks.

Let's hope they learned the lesson of how happy it made us that most cheap consumer cams can be used as (mini) DVCAM decks. If they apply the same logic to HDV, everything should be ok.

[Toke Lahti]

<<<-- Originally posted by Barry Green : What Ignacio is referring to, about using DV tapes as data backup, leaves out an important bit: (unless I don't understand it properly...) they packetize the backup data within DV data packets. So the data on the tape looks (to the deck) as if it's DV data, with DV headers, so the deck can properly read it. It's not just pure raw data. -->>>

Ok, Barry, so you know the hdv stream structure, so it isn't put inside DV data packets?
Btw, anyone have any links to specs of these streams?

[Barry Green]

Ok, Barry, so you know the hdv stream structure, so it isn't put inside DV data packets?

DV and HDV have nothing in common whatsoever, other than that they're recorded on the same tape.

Obviously it is possible to design a mechanism that can read and interpret both modes (JVC's HD1, HD10, and Sony's FX1 all do it). Here's to hoping that more manufacturers do. But existing decks, decks that are designed strictly for DV, have no clue what to do with HDV-format data.

[Toke Lahti]

Seems to me that here more like opinions talks than knowledge.
Does anybody know the datastructure of hdv stream through firewire?
Any links to any specs?

[Heath McKnight]

Toke,

Go ahead and buy an FX1 or HD10 and shoot HDV footage, then put it into a DV deck and report your findings to us.

heath

[Rob Lohman]

Both DV and HDV specs are NOT available for free. You will need
to buy them from SMPTE for example (who has PARTS of the DV
spec). I know how both DV and HDV look (in the broad strokes).
Yes it would be peanuts to get a DV deck to at least allow
processing of HDV (output or input of an analog signal will be
much more difficult since you would need to add MPEG-2 support),
but I'd bet they are not going to do this without analog support
and that will drive the price up (logically). You will always pay a
premium for new technology, that's one reason for me not to get
it yet!

DV spec is available at www.smpte.org:

SMPTE 314M-1999 Television - Data Structure for DV-Based Audio, Data and Compressed Video - 25 and 50 Mb/s
$56.0

and some others that might be needed (I don't think that 314M
includes the tape specs for example, not sure):

SMPTE 374M- Television - Mapping of Vertical Ancillary Data Packets and Extended Video Line Data into Video DIF Blocks of DV-Based 50 Mb/s DIF Stream Format
$36.00

SMPTE 396M-2003 Television - Packet Format and Transmission Timing of DV-Based Data Streams over IEEE 1394.
$36.00

I've seen SMPTE 314M (not thoroughly) and it contains information
on the DV bitstreams, DV encoding, VAUX & AAUX sections etc.


For the HDV spec you can go to: http://www.hdv-info.org/
Then click on "Inquiries about License" or the link to "Guide to
Obtain HDV Specification License". Them not listing a price is a
good indication on what it will cost (much!).

[Chris Hurd]

<< Seems to me that here more like opinions talks than knowledge. >>

If this is your impression, then perhaps you're in the wrong place. You might want to seriously consider taking your questions to some other online HDV community (there are plenty of others).

Our goal here is to provide accurate technical information and that has been done in this thread to the point of exhaustion. If the answers to your questions are not the answers you want to hear, then I'm sorry but there's not much that can be done about that, except to say that you'll probably have better luck at some other site.

I'm also sorry to report that normal DV decks most definitely will not play back HDV material, and that fact has been demonstrated in this thread by the people who own the gear. They certainly have no reason to lie about it. When someone refuses to accept an answer which has been backed by plenty of empirical evidence, that begins to make me wonder if the poster has a hidden motive. I don't appreciate that sort of thing, and that's when I begin to lock threads.

If you're not happy with the answers you get here, please look for them somewhere else. Thanks,