USB vs Firewire

[Magikx21]

I recently got a Sony Digital 8 cam and noticed the poor quality and large frame drop count using USB, so I ordered a firewire card for my notebook and I've been wondeing just what is the speed difference. I know the firewire runs 400mbs tops but what is the speed of USB?

[johns0]

USB we use most today, version 1.1, was designed with a maximum data transfer rate of 12 megabits per second (Mbps).Usb 2.0 runs at a top speed of 480mbps.

[Soopafresh]

Even though the published transfer rates are almost the same (USB 2.0 vs 1394 Firewire), the Firewire is a whole lot faster in real life. Dunno if it is the drivers or just the hardware, but Firewire is quicker.

[Magikx21]

thanks for the info

[mpack]

Dunno if it is the drivers or just the hardware, but Firewire is quicker.

It's more likely to be the protocol. USB is like a networking protocol, firewire is designed for point to point communications (I don't know if it even can be multidropped - I think not). Anyway, if you allow multidropping, as you do on a network say, then your protocol has to be designed to cater for non-data transfer tasks such as packet addressing and routing, dealing with contention between the different devices etc: and since some of the bandwidth is given over to these tasks you get less throughput - even on the same underlying physical medium - than a protocol that doesn't have to worry about those things. So, the theoretical "max throughput" figure doesn't always tell the whole story.

On the other hand... if USB 2.0 has a theoretical max of 480mbps then I would have guessed that it was designed so that, once typical protocol overheads are taken into account, it had roughly the same performance as a 400mbps firewire connection (assuming that only a single master and slave are attached). If firewire is still faster in your experience then maybe it is down to the actual hardware or driver implementation.

[edDV]

As far a Sony DV cameras go, the USB output is a realtime streaming format intended for live webcasting and is in the low Kb/s.

DV video (as transferred over firewire IEEE-1394) has a fixed 25Mb/s video stream but actually transfers close to 35Mb/s over IEEE-1394 due to the addition of audio, error checks and metadata. The DV stream is recorded to tape or DV-AVI file at a rate of 30Mb/s or 13.5GB/hr.

Even though max transfer rates for IEEE-1394 and USB standards are far higher, those are the fixed rates used by Sony and other DV camcorders.

Never expect a high quality transfer from the USB port on a DV camcorder.

[redwudz]

mpack wrote: "USB is like a networking protocol, firewire is designed for point to point communications."

You can network with Firewire. Here's one guide: http://www.homenethelp.com/network/firewire.asp

It's quite a bit faster than 100Mbps LAN, but has the disadvantage of only short distance (15 ft. max unless you use extenders.) Works well for short distance transfer between two close computers for large file transfers.

[Magikx21]

will a firewire card for a notebook show speed differences from say a direct mobo firewire port or firewire pci card?

[mpack]

You can network with Firewire. Here's one guide:

Thanks, but I'm afraid you missed the point, which was about protocol design. Of course you can connect two computers together with firewire! - or with any other fundamentally point to point communications scheme, including RS-232. But, that doesn't mean that Firewire (or RS-232) is designed for networking.

USB is hardware/software protocol stack specifically designed for networking an unspecified number (ie. two or more) devices together, with particular emphasis on devices with low to moderate bandwidth requirements (which allows longer cable lengths). Firewire is designed to connect exactly two devices together over a short distance with a high speed data link. It is the different design goals that creates the performance difference between the protocols. Firewire doesn't need the complexity of USB, and hence can be simpler and faster, which is great: but less flexible than USB. Which protocol is "better" depends on what you require.

[redwudz]

will a firewire card for a notebook show speed differences from say a direct mobo firewire port or firewire pci card?

Probably not. The PCMCIA interface might be a little slower than a PCI interface on a PC, but still should be fast enough for Firewire. It would probably depend more on the individual FW card.

[redwudz]

mpack, I see your point. I wonder if the difference in speed, at least for DV transfers between FW and USB 2.0 is in the overhead. It also seems some USB 2.0 problems, at least with external HDs or DVD burners may lie in the chipsets used or the hardware instructions in the external interfaces . And/or the PC USB 2.0 interface?

[ropdoh]

I use a PCMCIA firewire card (Margi) to dump DV video to my laptop, and it can do that fine. I think DV video is practically the maximum bitrate for Firewire.

I have had problems with the harddisk write speed if my disk is fragmented. I think this is because laptop harddisks often run at lower RPMs than desktop ones

[edDV]

I use a PCMCIA firewire card (Margi) to dump DV video to my laptop, and it can do that fine. I think DV video is practically the maximum bitrate for Firewire.

I have had problems with the harddisk write speed if my disk is fragmented. I think this is because laptop harddisks often run at lower RPMs than desktop ones

DV transfer from a camcorder is always ~35Mb/s fixed rate vs. 400Mb/s IEEE-1394 standard. You are using a small fraction of the capacity of the link.

The dropouts you are seeing are due to Windows and background processes (including disk seeks) interrupting the mostly unbuffered 35Mb/s DV stream.

See this thread for a complete discussion of the issue.
https://www.videohelp.com/forum/viewtopic.php?t=248968

If you were transferring a DV-AVI file over a networked IEEE-1394 link, it would burst considerably higher than 35Mb/sec limited only by the PCI bus and HDD controller efficiency.

[logixrat.01]

Thanks to Magicx21 for asking this question. I too have been wondering but haven't been able to post due to a 48 hour wait period when subscribing to these boards. Also, thanks to the kind souls that provided firm answers.

Now that it has been established Firewire is indeed better than USB 2.0, what brands/models of cards are recommended? I have a Dell tower with lots of USB 2.0 ports, but no Firewire!

Thanks in advance!

[canadateck]

Thanks to Magicx21 for asking this question. I too have been wondering but haven't been able to post due to a 48 hour wait period when subscribing to these boards. Also, thanks to the kind souls that provided firm answers.

Now that it has been established Firewire is indeed better than USB 2.0, what brands/models of cards are recommended? I have a Dell tower with lots of USB 2.0 ports, but no Firewire!

Thanks in advance!

I would go with a cheap card, I feel the 60$ ones work just aswell as the 12$ ones.Many people feel this way to.

[edDV]

Almost any resonable quality card with OHCI compatibility (for XP). Make sure you can return it and get another.

[Soopafresh]

http://www.newegg.com/app/ViewProductDesc.asp?description=15-104-218&depa=0


http://www.newegg.com/app/viewproductdesc.asp?description=15-124-005&DEPA=0

http://www.newegg.com/app/ViewProductDesc.asp?description=15-126-001&depa=0

[docrobb]

Don't know too much about dv transfer but I do know there are significant problems with VIA USB setups and using an external DVD-RW. Usually craps out, generating another coaster. Typically yoou get a SCSI command aborted error when burning with Nero and probs with other progs have been reported too. Just wondering if this is related to the problems described here. See the following link for discussion of Scsi command abort error.

http://forums.afterdawn.com/thread_view.cfm/1/102002

[logixrat.01]

Thanks for the links to the different cards. I like the Koutech and SYBA ones in particular. The Koutech seems to have alot of positive reviews. The SYBA only has 1 and it is a Linux user, but I suspect it would be okay. The SYBA is attractive as it has the 3+1 connections vs. 2+1 and is about $5 cheaper overall w/ shipping.

Anyone on here have + or - experiences with either brand? Also, what could I hook up with the internal connection? I thought it may be used to route a connection to the front of your tower.

[hsugawar]

It's more likely to be the protocol.

True.

USB is like a networking protocol, firewire is designed for point to point communications.

Wrong.

Typically, USB only implements point-to-point communications between a single computer and multiple peripherals over a multiplexed physical line and there's a strict distinction between the upstream side (PC) and the down stream side (peripheral device). It's not usually possible for the peripherals to communicate to each other directly or for 2 PCs to communicate to each other over USB without a special device (and software).

On the other hand, IEEE1394 is designed to network multiple devices in a kind of "daisy-chain" fashion. See FUNDAMENTALS OF FIREWIRE.

One addition to the IEEE1394 discussion is that it supports an isochronous protocol which works like a stream protocol without handshaking. This is what is usually used for the communication between a DV camera and a capturing card for its efficiency.

hiro

[Mythos2002]

One other thing to mention is that Firewire stays at a constant speed of 400 Mbps(1394) or 800 Mbps (1394B) while USB bursts at 480 Mbps. What I mean by burst is that USB sends up to 480 Mbps of data, stops, and then sends another 480 Mbps of data. Firewire constantly sends 400 or 800 Mbps. USB also relies on your CPU while Firewire doesn't.

I'm not knocking USB as it has its own advantages, but Firewire is better for video transfer.

Mythos

[mpack]

Typically, USB only implements point-to-point communications between a single computer and multiple peripherals over a multiplexed physical line and there's a strict distinction between the upstream side (PC) and the down stream side (peripheral device). It's not usually possible for the peripherals to communicate to each other directly or for 2 PCs to communicate to each other over USB without a special device (and software).

I'm aware of how USB works - I was deliberately avoiding getting into technicalities. In your comments you seem to be blending together features of USB hardware vs the USB protocol. Yes, USB hardware connections are point to point in the sense that each transmission line is electrically isolated from every other one: it is not a true multidrop in the sense that, say, RS-485 or Ethernet is. But, the USB controller (and comms protocol) still sees all devices which are downstream from a single USB port as being part of a single network, sharing a common bandwidth and a common addressing scheme. The master-slave relationship between the controller and peripheral devices exists in order to avoid "bus contention": it is much more robust in that regard than, say, a token ring approach, but it does mean that a great deal of potential bandwidth goes to waste.

I'm more hazy on how Firewire works: I've only ever seen it used for point to point, between two devices. Thanks for your comments on that.

[hsugawar]

It's better not to be confused with a physical topology/architecture with higher level protocols. USB does manage bus contention for its multi-drop archtecture, but it does not necessarily or immediately mean it can form a network for itself. It may depend on individuals' definitions but I would not call something a network unless it allows N-to-N communication. USB, as far as I know, simply and more precisely allows 1-to-N communication. I really doubt it allows communication between arbitrary two peripherals, which is against my definition.

Actually I don't like it to be called Universal Serial Bus which implies a mutli-drop bus architecture. In fact. USB is physically a single-rooted tree topology and logically a star topology for 1-to-N connections. These are quite different from a true bus topology such as Ethernet.

Again, my point itsthat USB does not implement N-to-N connections for itself. Networking is possible over USB using higher level protocols such as IP using USB-Ethernet dongles, but it's not a USB feature. In this sense, even an RS232 connection can be used for networking if carries SLIP or PPP.

As to real applications, agreeing with you, mpack, I have not actually seen something with IEEE1394 other than 1-to-1 connections, but it by design does allow N-to-N connections not only at the physical and link levels but also at higher (real) information-transfer levels.

hiro

[mpack]

It may depend on individuals' definitions but I would not call something a network unless it allows N-to-N communication.

Yes, this discussion does seem to come down to definitions. Your definition of networks is what I believe are usually called "peer to peer networks", which are the most usual kind for PC LANs, but not (say) in industrial control applications, which are often master/slave just like USB - and for the same reason, ie. because their behaviour is more robust and deterministic.

In my definition (which I believe is standard), a network is simply any method for connecting a number of devices together and transferring data along a (physically or conceptually) shared comms channel. Various protocols have various features, and direct peer to peer data transfer is not necessarily a requirement. This was what I had in mind when I used the "network" term previously.

[hsugawar]

Thank you for the explanation. Let me start calling my multi-port serial card a network device because communications are multiplexed through the device driver :P . Well, I'm just kidding, don't take it seriously...

hiro

[mpack]

Well, I'm just kidding, don't take it seriously...

I appreciate that you are joking, but seriously: the distinction with your multi-port serial card is that there is no unifying protocol built on top of it to allow information to be passed between connected devices. If such a protocol existed then it could be the basis for a bona fide network. Networks have after all been built with RS-232 connections in the past (and not so long ago either...).

Anyway, this little discussion, while interesting, is off topic I think.

[hsugawar]

Yeah, off topic indeed. BTW, did you know that Windows XP lists IEEE1394 and LAN in the "Network Connections" but not USB?

hiro

[paulw]

An interesting link on the Difference between USB2 and Firewire.

http://www.usb-ware.com/firewire-vs-usb.htm

[ofbarea]

In laptops is better to use firewire because of the CPU utilization. With USB it will almost double the CPU utilization at a given task.

[edDV]

An interesting link on the Difference between USB2 and Firewire.

http://www.usb-ware.com/firewire-vs-usb.htm

Here is a more comprehensive IEEE-1394 FAQ including audio info.
http://www.ioneconnects.com/1394_FAQ.htm#1394,%201394a,%201394-1995,%201394b

Then there is the classic DV FAQ by adam wilt
http://www.adamwilt.com/DV-FAQ-editing.html#codecs

This MS link explains how IEEE-1394 works in XP and how to bridge a IEEE-1394 link into your MS network. IEEE-1394 can be used in far more complex networks.
http://www.microsoft.com/windowsxp/using/moviemaker/expert/bridgman_02march25.mspx