Usb 2.0 vs. IEEE1394.

Theoretically, USB 2.0 Hi-speed (or full? I'm confused...) is rated at 480Mbps and IEEE 1394a is rated at 400Mbps (IEEE 1394b is rated at 800Mbps but your DV and MOST IEEE1394 devices out there are "a" only).

I'm not sure having only tried a Panasonic DV before, but the USB connection could only let me download photos but not videoes, but that was USB 1.1 anyway (12Mbps max.).

A IEEE1394 Cardbus adapter let me download a whole DV tape without a dropped frame.

Realtime compression is another thing then.

in the real world, you'll find that firewire will have a better transfer speed than usb2!

This is because IEEE 1394 is guarranteed at 400mb/s yet USB 2.0 can go as high as 480mb/s, yet this is not guarranteed.  Now, considering either of those will have to be on the PCMIA card bus, it will not be as fast as 400mb/s, yet either way you look at it, IEEE 1394 is a better choice...for an even better transfer rate you can get Firewire800 (same as IEEE 1394, but faster)...you probably do not need this, unless you need to transfer HUGE (Multi-GB) files.  (If you had a desktop, then IEEE 1394 would be guarranteed at 400mb/s.

 

If it's still not clear, just ask!

doesn't matter, notebook/desktop/server/PDA.   there is transaction info, data integrity, protocal overhead for both protocals.  

although i would agree that in general 1394a isn't much, if at all, slower than USB2.  USB2 devices are cheaper to make and more systems ship w/ USB2 than 1394a, thus why  you only see 1394 video and hard drives.  (unless you are a Mac person)

no no, see, it is...on a desktop as i stated, on a notebook, however, the pcmia card bus slows it down.

1394 isn't "guarenteed" 400Mb/s anymore than USB2 is 480Mb/s.  For video though you should use 1394 since it allows devices to generate transactions and under system loads this will be more reliable and drop less (or no) frames.  USB2 on the other hand is poll based DMA engine, thus a USB2 device can not write to memory directly.  Instead the USB2 host controller/driver has to continually ask the device "any data available" for it to transfer data.  Unfortuantely no USB2 devices support Isoc data types even though the software and host controller does.  This would "solve" the problem of dropped frames

Short answer, for video use IEEE1394.  USB2 is generally pretty fast and is cheaper than 1394 for devices such as hard drives, still cameras, etc

This is sort of true...you see more products shipping with USB in general, considering there are two of them, and USB has been the norm for Windows users and it is more widespread amongst them...also USB 2.0 is backward compatable with USB 1.1 devices and vice versa, however the connection will only be as high as USB 1.1 speeds (12mb/s).

 

Reading over my statements about the connection speeds I realize that I wasn't making myself entirely clear.  The connection of firewire is guarranteed between the actual card and the device/wire, not the necessarily between the computer and the device/wire, but the data has to travel over the system bus before you can actually tell the speeds...I hope that cleared things up/made a little more sense.