dv: can it have dropped frames

[maansingh169]

using pinnacle studio 9 plus

and using a miniDV camcorder..

i was reading somewhere that when connecting the camera via firewire....and using the "capture" utility like studio 9.....i am not really capturing but i am really transfering video.............
correct me if i am wrong.....i am thinking it is like transfering data from a floppy disk?
now that seems kinda of wierd....since you are actually playing back the video while transfering the files to the computer........so there should be no dropped frames when doing this...........like moving files over from a floppy........(there is no data loss)
then if this is true then i could be multitasking and doing other things ans still have a high quality video file DV avi file on my computer................

please tell me if i am wrong or right

[alstatr]

maansingh169,

You are right and wrong. You are correct that capturing a DV tape is like transferring data but you still can drop frames if you are doing other things on the computer while it is capturing. The only reason it is like transferring data is because the video on the DV tape is already digital but the computer still needs all its resources to capture all the frames.

Hope this helps, I'm pretty sure this is the answer you were looking for.

alstatr

[bugster]

DV via firewire is transferring of data rather than capturing in the traditional sense. There is no conversion of data from analogue to digital as with a 'normal' capture card. There is still the possibility of dropped frames though. The data is read from the tape by the camera in 'real time'. i.e normal tape playing speed, and then sent over firewire. If your PC cannot read the data quick enough, or save it to dosk quick enough, you can get dropped frames, so unless you are VERY confident about your PC and its subsystems, I would not reccomend multi-tasking whilst transferring via fire wire. Anything that is disk intensive is definatley out and although the processing overhead of firewire is quite low, any processor intensive apps could cause a problem also.

So,. IMHO, leave it to 'capture' in peace

[lordsmurf]

For comparison, a Windows computer (when copying other files) would either abort the transfer or slow down the transfer (or just plain lock up!) if you were copying super-large files from one hard drive to another.

To prevent that kind of problem, DV insists on sustained data rates, and their fix is to drop frames (actually, just drop data which has the frames) instead of locking up, aborting, etc.

"Capturing" is a word intended to mean that new data is being created in the digital realm. With DV, this is not happening, nothing new is being made. You're moving from A to B.

DV transfer methods are most analogous to data recovery, which is a process that takes whatever it can get, while it can get it. Full files, partial files, whatever it can find.

[junkmalle]

Think of DV capture like a conveyor belt:

The camera puts frames of video onto the converor belt and the computer takes them off and puts them in a file. Unfortunately there is no flow control. If the computer can't take frames off the conveyor belt as fast as the camera is putting them on, some of the frames will fall off the end of the belt and smash on the floor. The computer has no way of telling the camera to stop putting frames on the conveyor belt.

Using the same analogy for a disk to disk copy: there is a mechanism for flow control. If the receiver is falling behind it just tells the sender to stop sending for a while. Or even simpler, the receiver simply requests small packets one at a time; it doesn't request another until it's done with the first.

[lordsmurf]

Reminds me of I Love Lucy and the chocolate factory, or the banned Donald Duck episode and the Nazi ammo factory.

[maansingh169]

alright thanks for the information

one more question...........so if it is just transfering data back and forth.........and i am not expirancing dropped frames...............
that means........i can transfer to my cpu.........edit (cut and move around video) and put it back on to the MiniDV camcorder.......with no quality loss or anything.......since it is only Data that i am that i am removing moving around.........

[junkmalle]

alright thanks for the information

one more question...........so if it is just transfering data back and forth.........and i am not expirancing dropped frames...............
that means........i can transfer to my cpu.........edit (cut and move around video) and put it back on to the MiniDV camcorder.......with no quality loss or anything.......since it is only Data that i am that i am removing moving around.........

Yes, as long as your editing software doesn't decode and re-encode the data. Cut and paste operations don't require any re-encoding since each frame of DV is self contained (unlike MPEG where many frames only contain the differences from the last frame). But if you add transitions (fade out, 2D/3D effects, etc) or color corrections the data will have to be re-encoded -- at least those portions that are effected. Every time you go though a decode/encode cycle you will lose a little picture quality.

[maansingh169]

but is the quality loss visable to the NORMAL eye.....

[lordsmurf]

but is the quality loss visable to the NORMAL eye.....

It depends on what format you convert to, and the settings you use.

[ZAPPER]

but is the quality loss visable to the NORMAL eye.....

Generaly I don't think that you would notice any quality loss from a simple cut, rearrange, splice type editing session. But there is always a catch. Like it was stated before, when you start to get fancey with fades and color shifts or whatever other effects, you are actually kind of tampering with the orginal video data and the outcome may be less than pleasing to your eyes. (eventhough all of the data is still there)(kind of) Some programs handle these things quite well and others can make effects look like hell. Most do a pretty good job though if you don't over do it.

QUALITY and NORMAL are kind of subjective. As for quality (not going by a bit for bit technical compare) be sure that you try to judge the output on the screen that the video is intended to be shown on and don't worry too much about the data. And for normal the same is true. If it looks good to you, it will most likely look good to others.(barring the everyday critics that would never be happy in any case) And if things don't look good to you there is a good chance that it won't look good to others. If you are an extreme perfectionest, be advised, there are alot of imperfections in this video world. Most people don't even notice though.

[guns1inger]

If I am working in AE, I will output (whenever possible) to an uncompressed format. I do this because the DV output from AE is often soft and noisy. I can load the uncompressed footage in Vegas and output at much higher quality than AE can. DV may be a standard, but not all DV encoders are created equal (and the standard MS DV codec is one of the softest).

Trust me, the difference is more than visible to the naked eye, especially if intercut with good footage.