What is "DV"?

[justified]

I was looking for capture cards recently (and still am) and I came across a few that said they capture DV. What is DV?

If a capture card captures DV will it also be able to capture from my ExpressVu box and VCR?

[Scarymon]

DV is digital video, usually from a digital video camera.

[lordsmurf]

This is from a new page I plan to add on lordsmurf.com ... there may be a few errors, as this is a pre-published, not-final, BETA version ... but I thought it would help to post it now ...

For one, I know I need to include more information on 4:1:1 and 4:2:2 and 4:2:0 in there somewhere.

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DV capturing myths & FAQ

This page is more like a rant, moreso than a guide or FAQ. But the information is important to know.

1. DV is a single format. "DV" was initially the codename for a new "digital video" format. The name stuck. Now known simply as DV, it is the name of this single video format compression. It is not a category in which all digital formats fall under, as in "DV" and "analog". An MPEG file is not a DV. An AVI file is not a DV, although a DV can be an AVI. A DVD is not a DV. A VCD is not a DV. Understand? DV is a digital format of video. But digital video is not necessarily a DV.

2. You do not "capture" DV. Yes, you heard me, you DO NOT capture DV. You TRANSFER the files. In the world of video, the term "capture" refers to the re-acquisition of motion images in a format that is different from the source format. With DV, re-acquisition does not occur. The information is merely transfer from point A to point B, using special wires and software. You do not "capture" from a DV camera any more than you "capture" from a floppy disk.*

3. "DV" is not a wire or port. Again, DV is the name of the video format. It is not a wire or computer port. The wire most often used for DV transfer is called an IEEE1394 wire, also known as "firewire".*

4. A video capture card does not need "DV" to be good. A non-DV-based video capture card has zero relation to the DV format and the firewire cables involved in its data transfer. In fact, it is suggested to stay away from video cards that have had "DV ports" (merely IEEE1394 ports) installed on the card. As was the case with the ATI All In Wonder 8500DV, the "DV" aspect of the card caused more problems than not. Plus the firewire ports in use were of substandard quality. If you want to work with DV, buy a high-quality dedicated firewire card.

5. DV-based capture "cards". A DV capture device, like the respected external Canopus ADVC-100, is a piece of hardware that accepts the video signal it is given and then converts it to DV data. The DV data is then fed to the computer. The computer can either accept this raw DV data via DV transfer software, or the user can choose to use a software capturing solution to convert it to another format on-the-fly. Because of how it works, some videographers choose to discount it as being a true video capture card. This is because most internal computer capture cards allow the user to select which format the video is captured in, whereas the DV capture devices can only hardware-capture in DV format. Even if the user decides to software-capture the transferred data, it was already compressed to DV by the hardware, and once compression takes place, it cannot be undone.

6. Video camera pass-through. See previous item. This method is identical to the DV-based capture "cards" method, except the camera is acting in place of the dedicated DV capture device.

7. DV is not a perfect format. In fact, it's not even one of the best formats, it's just very popular. The DV format is often criticized for not having a standardized codec and for having hue problems. The red hues are often overpowering, as can be the greens, causing unpleasant video color quality. The format can also suffer from pixelation of bright colored areas. These problems are not seen on lesser-compressed formats. DV was a balance between editing quality and file compression, favoring editing. MPEG is similar in this regard, although it favors compression.

8. An AVI is not necessarily a DV file. An AVI file is a container format. It can hold many video formats. An AVI can hold DV, Divx... even MPEG. Because a DV is not a standalone format, merely a codec-based format, it must be put inside of a container file. The container used for DV is AVI. But an AVI is not a DV. Understand?

9. DV is not a DVD. I just had to say that one more time. Again, DV is a single format of video compression. A DVD is a disc type and a playback format. A DVD uses MPEG files and audio files muxed into VOB files with IFO and BUP navigation. DV is not at all related to a DVD.*

10. DV has no relation to TBC. The DV format and a time-base corrector has no relation. Some salesmen at B&H Photo and Video are guilty of suggesting DV is a TBC replacement, which is so wrong it's laughable.

I hope this will get less questions asked regarding the DV format.

[ZippyP.]

I was looking for capture cards recently (and still am) and I came across a few that said they capture DV.

Capture to DV or capture DV. Like it says above in Lordsmurf's post, when most people say "capturing DV" it's really just a transfer of digital data, usually from a camcorder to a PC via a Firewire port. The Canopus ADVC-100 "captures to" DV, which is an analog to digital conversion, then transfers it via firewire to a PC. The ADVC is a great choice for a capture device BTW.

[justified]

Thanks that helped a lot. This DV thing is not at all what I'm looking for.