Capture DV @ 352 x 576??? is it possible?

[buttsy00]

Hi,

I was wondering if someone could tell me if it's possible to capture DV via my firewire card at the resolution of 352 x 576?

I have limited hard drive space so I would like to capture at that size then encode into a VCD because I don't have a DVD burner... yet!!

Can someone tell me if this is possible and what program would be the best for doing it?

[Heavensent]

IM NOT SURE ABOUT THIS
but i dont think it works that way...
the resolution has nothing to do with HD space.
DV has a fixed bitrate (cant remember the exact bitrate)
so lowering the resolution (even if you find a way) wont help you.

can someone confirm that?

[henk schuifkaas]

He's right. You don't "capture" DV, you just copy the video 1:1 from tape to your harddisk. Any resizing will have to be done afterwards.

[dh]

buttsy00's question may be put in this way:
If it is possible to capture in DV format (from analog source) at the resolution of 352x576?

[geek rock]

buttsy00's question may be put in this way:
If it is possible to capture in DV format (from analog source) at the resolution of 352x576?

that's the same as the original question, and the answer is no.

DV format is one fixed resolution.

[Thorn]

DV is 720x480 (for NTSC) at 13MB/s. If you can't fit that much on your hard drive at a time, you have a couple of options:

1. Capture one piece at a time, then encode and delete the original. Repeat, then splice the results into one file.

2. Get an analog capture card, and capture any way you want. Be prepared for some lost quality, because HQ (lossless) analog capture takes at least 2x the space at the same resolution unless you take a hit on quality. DV is lossy compression of about 1:5.

3. Look into a cheap extra HD.

[buttsy00]

I appreciate the help guys....

Let me rephase the question...

Can I capture at 352 * 576 via a firewire connection? Doesn't necessarily have to be DV, I am happy to use a compression codec such as huffyuv but I would just like to use my firewire connection to capture not a capture card.

The reason being is I have a capture card which works fine but on some vhs tapes I drop a lot of frames (some other vhs tapes I drop no frames) and with a few tests that I have done I have connected the vcr to my dv camcorder then transferred to pc via firewire and I haven't dropped any frames at all but I am getting huge file sizes because it is at 720 * 576.

Any help would be appreciated.

[Craig Tucker]

No firewire is used for digital transfer (it just transfers the files from cam to HD with no alterations to the data), what you are asking for is analogue capture. If you are dropping frames with some VHS tapes, this is probrably down to poor quality tapes. You could try and improve the situation by using a TBC.

And as mentioned the filesize is nothing to do with the resolution, it is simply a product of the bitrate and the duration of the file.

[buttsy00]

The vhs tapes I seem to be dropping frames on seem to be the newer and better brand tapes....

What is a TBC?

[Craig Tucker]

Time Base Corrector

http://www.broadcastpapers.com/sigdis/timebase.doc

[buttsy00]

Thanks Craig,

Perhaps I do need a TBC but what is it exactly? Is it something that I plug in to my computer? Is it something that I plug in to my VCR?

That document doesn't really explain that?

How much does it cost? Where can I get it from?

[Craig Tucker]

It goes in line between you VCR (playing device) and Capture card (recording device).

From the doc

TBCs are needed to electronically make television pictures played back from imperfect VCRs and tapes as near perfect (stable) as possible.

What Is Time Base Error?

It is mechanical error or change. In the case of video tape, the errors are introduced by temperature, humidity, drag and tension changes which alter the physical size or shape of the tape at the time of playback versus these same parameters at the time of recording. In the case of the VCR these are errors introduced by mechanical size, shape and condition of the tape path, which changes the physical size and shape of the tape at the time of playback versus these same parameters at the time of recording.

Changes in size or shape of video tape smaller than one thousandth (1/1000 of an inch on a day-by-day VCR to VCR basis is nearly impossible -- electronic control of these mechanical errors in a TBC is nearly perfect.


I posted 2 links above one of them has prices. I just did a quick google search for TBC and that was the first one to come up.

Just search google for time base corrector, one of the most popular mekes I believe are Sima.

[Richard_G]

I think some of you may have missed the point to the question. Capturing from VHS using analogue may well cause dropped frames on some tapes. The answer to this may well be to use a TBC. By connecting VCR - DV camcorder - PC Firewire, he almost certainly is using a TBC built into the DV camcorder (as far as I am aware, all Sony camcorders have them built in, others may have as well). The question was, can he capture (transfer) a DV source via Firewire in 352 x 576.

The simple answer is NO. Dv is fixed size because you aren't capturing but transferring a file that is always the default size. It's no different to transferring a jpeg still image from hard drive to CD. If it started out at 1024 x 768 for instance, it will remain at that size. The act of copying that file from one storage medium to another won't alter the size or format.

Although we all know that the quality of VHS means that capturing in full DV resolution of 720 x 576 is overkill and 352 x 576 is perfectly adequate and will give no loss of what little quality was there in the first place.

The question has been answered (No you can't) but what is more important is why? A DV file will be in avi format which isn't a lot of use to anyone. To turn it into VCD, it needs to be encoded anyway. If the only reason is because you are limited on hard drive space, buy a bigger hard drive. It will probably cost you a lot less than buying a TBC or any other hardware. As you are talking PAL sizes (352 x 576 and not NTSC 352 x 480), I suspect you may be in the UK. I saw Hitachi branded 80Gb IBM 120GXP hard drives being sold at £49 at a computer fair yesterday. Under £100 will buy you the best part of 200Gb these days. Hard drive space is no longer an issue.

[Thorn]

If the reason you're looking at this is to solve the framedrops, the TBC may be a necessity - it doesn't matter how you capture if the source is missing a frame! If you find that the camcoder passthrough works, maybe you have a TBC in it and you can find a way to make it work at fullsize (since that's all can do with DV). You may also want to tweak virtualdub to get your capture card to work better. I found that fine-tuning some of the buffers in VD reduced my framedrops at fullres capture. If you're filtering or compressing that would also explain the lost frames.

On the note of capture without a capture card - most consumer-grade external capture devices are usb1.1 based and are complete crap. DV is the obvious exception, but that's because it uses firewire (and your camcorder). You may evenually see something good on USB2.0 since it has the bandwidth, but who knows.

[buttsy00]

Thanks guys...

I am having a problem now with the sound.

The sound is fine when I transfer it to pc but after encoding it to VCD using the template in TMPGEnc the sound is very distorted.

Any ideas how to fix this guys?

[buttsy00]

Also for 26 minutes of video when transferred to pc it is only around 5.5gb?

That seems a bit small to me?

What do you guys think?

[Craig Tucker]

No thats about right, DV is around 13GB/hour. Try using an external audio encoder with TMPGEnc, such as toolame or ssrc

[TBoneit]

Alternatively you can capture from firewire to VCD or DVD MPEG formats with Ulead Movie Factory 2. I just did a quick test from the Canopus ADVC-100.

Caveats: I use a fairly fast computer, needed to convert to Mpeg on the fly. The results were not nearly as good as capturing direct to DV format an converting later. It isn't what I would do for keepers.

It is a free 30 day trial though so you can give it a try, should capture to VDC, SVCD & DVD formats.

YMMV