Post by: sandbox on January 21, 2007, 01:57:27 AM
QUOTE
In the not too distant past, there was a clear distinction between USB and FireWire. USB 1.1 could not transfer high quality DV; loosely defined as 25 frames per second (fps) with each frame being 640x480 resolution, due to USB's transfer limit of around 11Mbps (or around 1.5MB per second). Transferring DV requires a transfer rate of at least 3.6MB per second, which left FireWire as the only option due to its ability to work at 400Mbps, or up to around 50MB per second. Then along came USB 2.0 with a transfer rate of 480Mbps or around 60MB per second.
At first glance it would appear that USB 2.0 is even faster than FireWire; however speed is not the only issue when it comes to DV. One serious issue with USB 2.0 is that it can not guarantee a specified data transfer rate. This is due to USB 2.0 being a master-slave technology, which means it needs a computer's CPU to coordinate the appropriate data transfers. While not a problem when dealing with low demand peripherals such as Web cams, scanners, printers etc, digital video requires dependable performance to avoid dropping video frames.
FireWire is a much more independent technology in that it works in a peer-to-peer relationship. For this reason, many professional DV users are now able to download their video from a DV camcorder to an external hard drive without the use of a PC. Finally, and most importantly, FireWire delivers data consistently at a specific rate. If you want to work with video, even to edit the family movie, go with FireWire.
At first glance it would appear that USB 2.0 is even faster than FireWire; however speed is not the only issue when it comes to DV. One serious issue with USB 2.0 is that it can not guarantee a specified data transfer rate. This is due to USB 2.0 being a master-slave technology, which means it needs a computer's CPU to coordinate the appropriate data transfers. While not a problem when dealing with low demand peripherals such as Web cams, scanners, printers etc, digital video requires dependable performance to avoid dropping video frames.
FireWire is a much more independent technology in that it works in a peer-to-peer relationship. For this reason, many professional DV users are now able to download their video from a DV camcorder to an external hard drive without the use of a PC. Finally, and most importantly, FireWire delivers data consistently at a specific rate. If you want to work with video, even to edit the family movie, go with FireWire.
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Post by: Texas Mac Man on January 21, 2007, 11:34:08 AM
USB: Transfer Speed Compared to Other Technologies
Note that USB 2.0 @ high data transfer rates of 480mbps is higher than Firewire 400 @ 400mbps, however, the USB 2.0 rate is the max rate & rarely achieved for large data transfers. The Firewire transfer rate is essentially uniform at the stated rate.
It's interesting to note the slow speeds at the top of the table. 10 to 15 years ago we thought they were fast compared to those in the 80s.
Post by: giantmike on January 21, 2007, 05:21:32 PM
Thus, some simple math:
480 Mbps * 0.70 = 336 Mbps (USB 2.0)
400 Mbps * 0.90 = 360 Mbps (Firewire 400)
So taking into account the efficiency of streaming using these protocols, Firewire actually has a higher theoretical max bandwidth than USB 2.0.
Post by: Xairbusdriver on January 21, 2007, 10:04:24 PM
Post by: krissel on January 22, 2007, 02:48:36 AM
Post by: tacit on January 23, 2007, 01:10:53 PM
QUOTE(krissel @ Jan 22 2007, 08:48 AM) [snapback]116628[/snapback]
Since it was Apple that came up with the FW standard, it's obvious why those 'other' computer makers weren't jumping to add it to their machines.
Not as obvious as you think. Apple comes up or controls lots of standards that other people use in their computers (for example, Intel originally came up witht he PCI standard, but the committee that controls the PCI standard is now controlled by Apple, not Intel).
The biggest problem with FireWire was cost. When it came out, FireWire was the best standard on the market for simple, high-speed, hot-swappable devices, and there was great interest in it--almost all the major PC vendors wanted it. So Apple got greedy, and set a very, very high licensing fee for it--about a dollar twenty per computer. That doesn't sound like much, but by way of comparison, the licensing fee that Intel set for USB was about twenty-five cents per computer. The PC motherboard industry is so fiercely competitive that the average profit margin on a $300 motherboard is only about seventy-five cents, so Apple's licensing fee for FireWire pretty much killed any hope that it would be widely adopted.
Apple later realized their mistake and dropped the licensing fee for FireWire to about the same as USB, but by then it was too late.
Post by: Texas Mac Man on January 23, 2007, 04:03:10 PM
Firewire, also known as IEEE 1394, is a wired inter-device digital communication standard, providing data rates of up to 400 Mb (megabits) per second. The Firewire standard consists of a serial input/output port and bus, a copper cable capable of carrying both data and power, and the associated software. Its ability to transmit video or audio data in digital form at high speeds, reliably and inexpensively, over cable lengths of up to 14 feet, has made it a very popular choice for connecting digital video devices to each other and to computers. The Firewire standard is supported by electronics companies such as Sony, Phillips, Panasonic, Canon, and JVC, as well as computer companies such as Apple, Microsoft, Compaq, and Intel, although many of these companies use the IEEE 1394 label for the technology.
Properties
The Firewire/IEEE 1394 standard has the following properties:
* Consists of both hardware and software specifications
* Completely digital--no conversion to analog
* Data rates of 100, 200, or 400 Mb per second
* Plug and play--connection is automatic once cable is plugged in
* Hot plug-able-- cables can be connected and disconnected while in use
* Flexible--supports daisy-chain and branching cable configurations
* Peer-to-peer--can connect digital video recorders (DVRs) to a computer or directly to each other
* Scaleable--can mix 100, 200, or 400 Mb devices on single bus
* Physically easy to use--no special terminators or device IDs to set
* Physically small--thin cables
* Inexpensive
* Non-proprietary--licensing is open and inexpensive
* Two data transfer types--asynchronous and isochronous
o Asynchronous data transfer--The traditional request-and-acknowledge form of computer communication for sending and receiving data.
o Isochronous data transfer--A continuous, guaranteed data transmission at a pre-determined rate. This allows the transmission of digital video and audio without expensive buffer memory.
History
In the mid 1990's, Apple Computer invented the Firewire bus for local area networking. At the time it provided connection speeds of 100 Mb per second, although speeds of up to 1000 Mb per second were planned for the future. The standard was soon embraced by computer companies such as Intel and Microsoft, who saw the advantage of the Firewire/IEEE 1394 system over the established USB connection standard for applications such as connecting storage and optical drives. Universal Serial Bus (USB) has a connection speed of only 12 Mb per second. As electronics companies began producing digital video cameras, they too looked to the Firewire standard for connectivity, to maintain an all-digital path for signal quality in digital video editing.
In late 1998, Apple, which held the primary IP for Firewire, began charging a licensing fee of $1 per port--so a hard drive with 2 Firewire ports would cost an extra $2 per unit to construct. While a nuisance in the thriving PC industry, the additional fees would have seriously hampered the future of Firewire in the electronics industry, which typically operates on very thin margins. By the end of 1999, however, the standard was operating under a general licensing group, known as 1394LA, that holds the essential patents relating to the Firewire/IEEE 1394 standard in trust. This is similar to the way in which the patents regarding the MPEG video compression standard are licensed. Companies can now license the IEEE 1394 standard for $0.25 per finished unit, regardless of the number of actual 1394 ports in the unit. The term Firewire, however, remains a trademark of Apple.
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Side note - Intel developed the faster USB 2.0 as competition to Firewire.
Post by: krissel on January 24, 2007, 10:38:04 PM
Post by: sandbox on January 25, 2007, 03:14:09 AM
The advantage of USB 2 over Firewire 400 was it’s backwards compatibility with USB 1.