Can someone please clarify the DV camcorder to PC process?

[jbarr]

I am struggling with a small point that I hope someone can clarify. Please clarify the process of moving DV audio/video from a camcorder to a PC via FireWire? (I'm specifically refering to moving DV data recorded onto a tape on the camcorder to a PC as opposed to "pass-thru" which, obviously, is a capture.)

Some have described this process as a "transfer" while others have described it as "capture". To me, the concepts are very different. Here's how I would describe each method:

"Transfer" is like a download. The data that is on the camcorder gets "downloaded" to the PC. In other words, a DV file exists on the tape and it gets copied to the PC resulting in two identical copies. No frame loss, not interferance, just a duplication of files deom one medium to another. The integrity of the copy is not dependent on the "power" of the PC because it is a data transfer like a modem download with some flow control protocol.

"Capture" is just what it says. The PC is capturing the audio/video in a stream as it receives it, writing the data into a new file. Timing is critical, and if the connection between the PC is marginal or if the PC can't keep up with the transfer speed, you will get frame dropping. This is not a "copy", but more of a "controlled dump". The integrity of the resulting file is dependent on the connection and the "power" of the PC (fast enough CPU and fast enough HDD.)

OK, that said, which is the method used by current miniDV recorders like the Canon ZR series?

On a related note, say the camcorder also has a media card (like the Canon ZR45MC) onto which video has been recorded. When the card is put into a card reader connected to a PC, when the data is copied from the card to the PC, is it (using the above definitions) "transferred" or "captured"?

Thanks!

[jtor]

As long as you're using your PC's firewire port, then you're 'TRANSFERRING' video from your camcorder to your PC.

Can't help on the media card. My miniDV doesn't have it. Sorry.

Hope this helps.

[Dragonsf]

"capturing" is a litlle bit more as far a conversion of data in involved.
But in your sense, getting data from the DV device (if taped or pass through or A/D converted), it's a captured.The data is in a stream, which speed cannot be controlled from the PC (besides the regular transport commands).This speed is independend fromyour capturing device, and so the PC must be fast enough, to catch the data and put them on the disk.At rates of 3550 KBytes/sec, you should expect a decent HW for such capturing.
On the other side, reading data from a memory device (like memory stick), the transport is controlled by the PC and such is a transfer (and not a capture).
This is my understanding of data exchange between PC and DV device.

[Issachar]

jbarr, I understand better now what you were trying to ask yesterday.

You're apparently thinking of the digital camera as a small computer that records the video and stores what you've recorded as a "file" only on tape or some memory device.
Then, you're apparently thinking that when you transfer from camera to computer, you're just downloading a file from one type computer (camera) to another, the PC.

Got it........
What is happening is that the camera has the electronics to convert the analog signal from the CCD device in the camera to a digital signal. It isn't really a "file" per se. It is simply digitized analog signal. (the CCD device is the part of the camera that the image is landing on after coming in through the lense.)

You don't have to download from the camera to the PC, a "file", and then watch it.

When you send an analog signal into a capture card, the capture card is converting it into digital info which is then stored on the computers HD and we can watch it on the screen at the same time. With a digital camera, the image is already digitized when it leaves the camera which is why capture cards have digital inputs (firewire) as well as analog inputs. They can accept info that is already digitized or they can accept analog info and digitize it for you. Once the info leaves the capture card and goes into the rest of the computer, there is no difference.
Both though are just info coming into the computer and can be seen on the screen as the info comes in. It doesn't matter that one is already digitized in the camera and one isn't. The one that isn't (analog), will be once it gets to the capture card. .... once they leave the capture card, going into the computer, they are the same. The capture card is simply an interface board between two discordant worlds. It talks analog on one side and digital on the other. It is a translator between two things that speak different languages. Many of them have firewire ports so they can receive info that is already digitized by something else (the camera) and just serve as a port of entry into the computer.

Issachar

[omoses]

"capturing" is a litlle bit more as far a conversion of data in involved.
But in your sense, getting data from the DV device (if taped or pass through or A/D converted), it's a captured.The data is in a stream, which speed cannot be controlled from the PC (besides the regular transport commands).

I have to say one thing: On DV-capture or transfer (both is more or less right) you have no control from the PC (if receiving). The DV-stream is sent via broadcast over the firewire, the sender alone decides, how fast and when it will send the data. The only thing is, that most devices ask before broadcasting the video-data, if any recipient is listening. If not, nothing will be sent (to keep the line clear). So if the recipient (PC) is too slow, you will miss some frames (which can happen in windows-machines quite often, even 500MHz P3, and the driver often do not recognize!).

For the wording:
Transfer is right, because you copy the data from the tape to the PC, doing a little filtering/adding data for the avi-file-format. But you do not re-encode the raw data. So transfer is right.
Capture is right, you capture the single video-frames from the broadcast stream to an avi-file. So capture is also right. It's like capturing analog movie, but with another hardware.
Both is right and wrong at one time. It's a mix of both with DV.

[jbarr]

GREAT answers! That really clears it up! You guys are great!

Now to go out and purchase that Canon ZR45MC MiniDV camcorder that I have been eyeing. Time to get going on this movie conversion project: I have about 120 or so 8mm film reels that I want to capture to DV. My goal is to capture, archive, and save to a high-quality format (.AVI or some such) and then down-convert to VCD. Later, when DVD formatting (or any new format that comes along) becomes less cost prohibitive, I'll use the original archives to down-convert to DVD. I have read other posts about variable speed projectors, flickering problems, film-chains, etc., so I feel pretty confident that I can tackle this with pretty good results.

I'll keep you all upadted as to my progress.

Thanks again!!!

[Dragonsf]

I think, you should be going for SVCD, which is nearer than VCD to DVD.And SVCD is mpeg-2 like DVD (just another framsize and bitrate).
There is only one way to preserve DV quality: record them to tape.There is IMHO no use to convert (S)VCD to DVD.
Storing them as DV-avi is another good idea if space is no issue:
For every 20Min of footage you need 4GB.

[jbarr]

While I definatly agree that the SVCD format is better quality, my problem is that my Sony DVD player won't handle SVCD disks. It does, however, handle VCD disks just fine. I am planning on storing the original .AVI files (and probably also the DV tapes) as an archive for future conversions.

[Dragonsf]

The big question is: how do you want to store such an amount of data?
let's calculate:120 films at 5 min=10 Hours=120 GByte.A lot of disks to be burned!