Can i transfer, DV through USB port ?

[LordVader]

i have a (4-pin to USB) cable, the 4-pin conector is the same as (dv out) in my camcorder.

can i use this cable to transfer dv content through the usb port ?

sorry by my ignorance , i don't have any experience with DV transfers yet.

i know is insane, because of the transfer rate. but i want to know if, it can be done slowly, but in a secure way.

[J. Baker]

DV goes through firewire but motion jpeg can go through the usb. The resolution is smaller with motion jpeg then DV though.

[LordVader]

most people say, that it can't be done, because of the transfer rate of usb.

firewire is about 400 MB/sec, but my hard drive don't write that size per seconds, so how is all these things related to firewire ?

i mean, the card receives 400mb/sec and my harddrive only writes 20mb/sec.

what is the big deal about firewire port then ?

[edDV]

You need to use IEEE-1394 transfer for DV. It is a constant 25-35Mbps stream. The DV stream is collected into a DV-AVI file at the PC.

If your camera has a USB port, it is used for stills and low resolution web streaming only.

[edDV]

I'm sure you mean 20MB/sec
All it needs to write is 25-35Mb/s so you are good.

[LordVader]

eD, I want to take advantage of the occasion, and ask you something about the resolution test with digital camcorders.

What is the procedure to make the resolution test, using the picture in black & white you have right there?

[edDV]

Do you mean the camera?
yes you would need a camera resolution test pattern.

Here is a link
http://www.bealecorner.com/trv900/respat/

They even have test slides that you can download and print. Match the frame edges to the arrows.

[LordVader]

thanks

[alsyed]

firewire has a bandwidth of 400Mbit/s, which equates to a maximum of 50MBytes per second.

USB2 has 480Mbit/s, which is max 60Megabytes.

your transfer/write performance falls under these maximum's so there is no problem with write speeds of the hard drive.

analogy: the speed of the hard drive may be reported as maximum 133Megabytes per second, but generally you will never hit that speed. That is the maximum speed it will support. Same goes with the firewire. Just about any modern hard drive and system will be be able to keep up with firewire/usb2 transfers.

[Richard_G]

All this talk about the theoretical maximum transfer speeds of different ports is irrelevant. The simple answer is that you cannot transfer DV video over the USB port because the camcorder won't output it.

Think of it this way, I have three DV camcorders and none of them have USB ports because DV uses IEEE 1394 Firewire. I also have a digital camera which has a USB port because that is what is used to transfer stills and low resolution webcam type video.

You have a DV camcorder that has a built in digital camera/webcam. The Firewire is there to use with the DV camcorder part of it and the USB is there for the digital stills camera part of it.

[rkr1958]

firewire is about 400 MB/sec, but my hard drive don't write that size per seconds, so how is all these things related to firewire ?

Firewire is 400 mb/sec which equals 50 MB/sec.

.... and my harddrive only writes 20mb/sec.

20 mb/sec is 2.5 MB/sec. I think you must mean 20MB/s, which is not even ATA33. What kind of harddrive do you have?

what is the big deal about firewire port then ?

My Camera DV Firewire is a 4-pin (camera) to 6-pin (PC) cable. The transfer rate, even though my firewire card can support 400 mb/s (25 MB/s) is 100 mb/s, which is 12.5 MB/s and exceeds the minimum 3.6 MB/s rate required to capture AVI from my camera. The firewire transfer of DV is lossless, given you don't drop frames. To me that's the big deal about a firewire port.

[Richard_G]

.... and my harddrive only writes 20mb/sec.

20 mb/sec is 2.5 MB/sec. I think you must mean 20MB/s, which is not even ATA33. What kind of harddrive do you have?

20MB/sec is about right for a SUSTAINED data rate (maybe slightly low but not by much). ATA 33 gave a theoretical maximum BURST rate of 33MB/sec but rarely managed to get much over 20MB/sec. ATA 133 has a theoretical BURST rate of 133MB/sec but in reality will probably struggle to get over 100MB/sec burst. Burst rates don't enter into it if transferring video, it is the sustained (i.e. Continuous) rate that matters.

I've never checked it on my current system but my old ATA100 system used to give a sustained rate of anything between 9 and 16MB/sec depending on whether it was writing to the inner or outer area of the disk, the amount of fragmentation, etc. This is why DV very rarely drops frames (requiring only 3.8MB/sec) but analogue capture is much more prone to it as the data rate can be much higher.

[edDV]

New 7200 RPM hard drives max out around 40-55 MB/sec for sustained transfer. ATA-100, 133 no difference. Those specs relate to the controller transfer capacity, the actual HDD moving hardware limits the sustained transfer.

Inside tracks vs outside tracks will have an effect but as Richard_G says, disk fragmentation and also background process disk interrupts will slow or stop the transfer if they aren't managed.

DV over IEEE-1394 is ALWAYS 25Mb/s for video plus audio, plus metadata, plus IEEE-1394 management and error correction codes. This varies but maximizes around 36Mb/s in the actual DV stream over IEEE-1394. Data stored to tape or the DV-AVI file averages 30Mb/s or 13.5GB/hr.

People get streams and file transfers confused. Streams are fixed rate. If the system can't keep up, you get dropouts.

File transfer is managed by the OS. The OS will transfer the file at a variable rate determined by its evaluation of the bandwidth of the transmission path. If parts of the file don't make it to the destination, the OS requests a resend until the file is complete and error free. This is not true with a data stream like DV. So you need to think in terms of safety margin and worst cases (like antivirus software deciding to take control of the HDD).

Everything to do with DV transfer over IEEE-1394 envolves a data stream like a hose. If you spilll any of it, the data is gone. DV camcorders and DVRs with firewire input only deal in streams.

The only exception to the above is when a IEEE-1394 link configured as a network connection or managed by a disk controlller (e.g. XP control of an external firewire HDD). In these cases, there is no streaming. The OS treats the IEEE-1394 as if it were any other connection for file transfer. In these modes, the peak 400Mb/s transfer speed is utilized.

[Richard_G]

Ed, couldn't agree more, but I wish you'd stop confusing me. I always have to look again as you talk in Mb/s (Mega bits), where I'm more used to dealing in MB/sec (Mega Bytes). We're both right but it looks confusing when one person talks about DV being 25-36Mb/s and someone else quotes 3.8MB/sec. I tend to think in MB/sec as that is what HDD data rates are usually quoted in.

I actually checked my old machine that used to give me between 9 and 16MB/sec (as it is now used by my daughter) and found that it is only ATA66. I couldn't find any benchmaking software handy so did a quick analogue capture on my machine with settings on as worse case as I could set without screwing all my settings totally. No dropped frames and a 30 second avi clip used just over 900MB, so I can handle 30MB/sec no problem. This probably explains why I never drop frames with DV and don't turn anything else off (in fact, I've even been browsing around here during transfer)!

[edDV]

Back in the mid to late 90's when MJPEG was being used, you could just barely reach 7-9 MB/s with SCSI II and III drives. Most people needed RAID zero then.

Today we have faster HDD and lower requirements with DV 3.8 MB/s transfers.

Still capture streams need to be treated with care. It's best to separate the capture drive from the OS drive to keep background processes from taking control of the drive.

[doppletwo]

I have a friend that says that his model of camera can transfer DV through USB2, but I am quite skeptical. The cameras I have used only tranfers stills like you said.

He probably got duped by a salesman. But isn't it possible though I have yet to see it that USB2 could handle DV.

It sounds like the specs on USB2 are high enough, but most camcorder makers just don't want to use both 1394(FireWire) and USB to transfer DV.

What do yuo guys think?

[Richard_G]

I think the main problem would be that USB2 is backward compatible. What would happen is that a camcorder manufacturer would produce a unit that outputs DV over USB. Dim punter then buys the camcorder and complains like hell that it won't transfer video to his computer because he's trying to use an ancient Win 98 machine with USB1.1 ports. It wouldn't take many before manufacturers name is being slandered all over the place.

[doppletwo]

Dim Punter? is that the UK Joe Sixpack?

Yeah I see what you mean about the confusion. I like it when everything only fits in the correct port.

[edDV]

Current Sony DV models transfer stills and low bitrate "NetMeeting" streams over USB. DV goes over ILink.

The problem is Sony didn't include an IEEE-1394 cable with the cheap camcoders, only the USB. So all the dweebs who don't read the manual come here complaining that the video sucks from their MiniDV or Digital8 cam when transferred to the computer.

The issue isn't whether USB2 couldn't somehow work for video transfer. It just isn't at this time especially for DV.

[doppletwo]

Yeah EDDV that's what I was thinking.

I am one of the few maunal readers I know.

I get a little anal about reading manuals sometimes.

When a got a toaster with a special bagel setting and stop buttons , I read the manual my sister laughed at me and said, "what you don't know how to make toast?"

Sorry for getting off topic I know this isn't the toaster forum.

[edDV]

Those bagel settings on the new toasters burn the surface. I'm going back to a toaster oven.

[Richard_G]

Dim Punter:

Dim = not very bright, not the sharpest knife in the drawer, not running on all cylinders, Dozy

Punter = Customer, or just member of the public.

Sony don't include an IEEE 1394 cable with their camcorders because they want you to buy one separately. I was charged £20 (nearly $40) for one! Mind you, being a Sony one it does have pretty purple ends with Sony i-Link logos on it.

[edDV]

Or you could get one online for less than $10.

http://www.cwol.com/firewire/1394_cables.htm

[Richard_G]

I did later, but at the time I wanted one now and was in a Sony dealers......

[LordVader]

well , i have a Quantum FIREBALLlct2 and a Western Digital WDC WD80.

I don't know to much about the real transfers rates of my harddrives, the only speed test i've used is the "NERO drive speed test".

the results are:

quantum fireball - 20,000 Kb/s ( this one is 40GB )
western digital - 50,000 Kb/s ( and this 80GB ) :P

both hard drives are connected to a Maxtor Ultra ATA/100 PCI adapter card.

Is obvius that if i'm planning to do a DV capture, i have to use the WD, right ?

it's kind of sad, i love my quantum

[Richard_G]

You could use either, you only need 3.8MB/sec, the Quantum is 20MB/sec and the WD is 50MB/sec.

But, as DV is over 13GB per hour, you'd soon fill up the Quantum!