So what do you think about USB 3.0 ??....and is it always necessary?

[Gray_Area]

To elaborate on the second question: the average american net user gets probably 10mbp internet service. Yet USB 2.0's 480mbp ain't enough for video streaming? This suggests to me an OS resource allocation problem.

Regardless, many of you know more than I do, so what's your answers?

[SavannahLion]

Well.... I'm not sure what you're getting at. USB isn't just used for video streaming you know. Neither is the internet.

And I could be wrong, but I'm not aware of any monitors that directly support a video stream from USB so.....

AFAIK, USB3.0 maximum speed limits aren't in consumer level products anyways. So it might be a while before we start hitting 3.0's speed limits there.

[CheffoJeffo]

To elaborate on the second question: the average american net user gets probably 10mbp internet service. Yet USB 2.0's 480mbp ain't enough for video streaming? This suggests to me an OS resource allocation problem.

Regardless, many of you know more than I do, so what's your answers?

I know that trying to derive anything based on the max spec of a device on one end, then ignoring everything in between is just silly.

But, FWIW, I am, while I type this, streaming HD rather nicely from an external drive attached to my notebook via USB 2, then streamed over N wireless to my iPad in the kitchen and not having any problem at all.

[Howard_Casto]

I think you are a bit confused man.  USB 2.0 is more than sufficent for video streaming and I've never heard anyone say different.  Perhaps you are referring to usb monitors?  Because the bottle neck there is the system, not usb.  Without proper hardware acceleration, any software-based usb video card is going to be slow as dirt. 

usb 2.0 was added because of harddrive speeds and nothing more.  2.0 is still too slow to keep up with the transfer rate of your typical sata drive, thus the need for 3.0. 

So to simplify, anything higher than 1.1 was added due to harddrive transfer rates.  This effects file access/transfer times and NOT things as trivial as streaming speeds.  Video streaming is buffered in ram you know. 


Now taking all of that aside, you've also got to remember that usb speeds are totall throughput.  If you start adding usb hubs into the mix, the max speed you get slows down.  Mind you it isn't anything as dramatic as a 4 port hub cutting the speed to 25% per device, but it is noticable.

[shmokes]

What if, instead of streaming a movie, I want to copy a 30 GB Bluray rip from my computer to an external drive. Or maybe I want to back up my 100 GB music collection or 2 TB video collection. Minutes vs. hours. Is USB 3.0 necessary?

[MonMotha]

High Speed USB 2.0 (as a note, you can actually make a low speed "USB 2.0" device) is rated at 480Mbps and typically attains on the order of 250-300Mbps.  This is more than enough to stream a Blu-Ray at native speed (54Mbps max by the spec).  The drive probably can't read the disc much faster than maybe 150Mbps (a 2x drive is rated 76Mbps), so plenty of room to spare even for full speed ripping.

Hard drives can go faster.  A low end 5400RPM consumer grade 1TB SATA drive can usually hit at least 500Mbps, which is a fair bit about the typical real-world performance of High Speed USB 2.0, but it's not crazy limiting.  A mid-range 7200RPM drive (not commonly found in off the shelf externals, but you could build one up yourself of course) can usually hit 750-1000Mbps or even faster, so High Speed USB 2.0 would be fairly limiting (easily restricting it to half its potential speed).  High end USB flash drives are frequently capable of 1000Mbps or more, now, so superspeed USB 3.0 really shines, there.

The 12Mbps (real world typically 8-10Mbps) offered by Full Speed USB (1.1 or 2.0, and yes, "Full Speed" is slower than "High Speed") is quite limiting for many forms of video streaming.  You can just barely fit a typical DVD into that, and any form of uncompressed or modestly compressed (e.g. MJPEG as used by many webcams, DV, HDV, etc.) is simply way too fast.  High Speed USB 2.0 is more than enough for all but uncompressed HD, though (uncompressed 480p at 29.97fps, 16bpp 4:2:2 is ~180Mbps).  Note that this means you could run a 720x480 dumb framebuffer at usable framerates on High Speed USB 2.0.  High Speed USB 2.0 can also keep up with DV, HDV, etc. from a consumer camcorder.

Super Speed USB 3.0 is nice for external video because you can run realistic PC resolutions without needing lossy compression or relying on lossless compression that's content dependent (and therefore may affect your framerate depending on what you need to redraw), but it's not really necessary for any form of compressed video.  I guess you could also use it as a replacement for HD-SDI or DVI/HDMI/DisplayPort when capturing from a prosumer/professional video camera, but I'm not aware of any actual implementations at this time (USB Video Class should support it, though).

As for backing up "large" amounts of data, things take a while.  At 1Gbps transfer rate (e.g. 1Gb Ethernet which gets surprisingly close if your PCs can keep up), you need about 3-4 hours per terrabyte at real-world speeds.  Note that your hard drive is not much faster unless it's an SSD or RAID array (0, 5, 6), so you won't see much benefit of Super Speed USB 3.0 (5Gbps, real world varies highly due to a ton of factors) compared to gigabit Ethernet, but Super Speed USB is of course also a viable option.  Super Speed USB mass storage should be comparable in speed, assuming your CPU is free, to a direct SATA connection (to include eSATA).

SATA can attain close to 6Gbps in the real world (which, note, due to the 8b/10b encoding means 600MB/sec, not the "obvious" 750MB/sec), but even a high end SSD will have trouble keeping up with.

If you've got a high end SSD on both ends of the copy connected directly to the PC via SATA, you should be able to copy 1TB in a bit over half an hour.  Super Speed USB 3.0 should, with good hardware, run a bit more than half that speed, so 1TB would take about an hour, and you no longer need a "high end" SSD to keep up.  Doing the same 1TB copy with High Speed USB 2.0 as the bottleneck would take nearly 8 hours, but you no longer need an SSD (just a middle of the pack revolving metal drive) to keep up.

If you want to copy 2TB, just double all those transfer times, of course.

FWIW, if Gigabit Ethernet isn't fast enough for you, 10 Gigabit Ethernet does exist and is rapidly becoming remotely affordable for consumer usage.  For the time being, there's no way any single other interface on your PC can keep up unless you have Thunderbolt (well, or you consider 4xPCIe, but you can't really hook that directly up to anything useful).  There's also a 40Gb and 100Gb Ethernet standard, but you (probably) can't afford it, and nothing you own (probably) can really keep up, anyway.

TL;DR: High Speed USB 2.0 has started to become limiting for external mechanical hard drives, though not by huge factors.  For high end external flash media (SSD, some "thumb drives", etc.), it can be very limiting and the higher speed offered by Super Speed USB 3.0 can make a major difference.  It's also nice for uncompressed HD video, but it isn't even remotely needed for compressed sources used for streaming and consumer media.

[Gray_Area]

TL;DR: High Speed USB 2.0 has started to become limiting for external mechanical hard drives, though not by huge factors.  For high end external flash media (SSD, some "thumb drives", etc.), it can be very limiting and the higher speed offered by Super Speed USB 3.0 can make a major difference.  It's also nice for uncompressed HD video, but it isn't even remotely needed for compressed sources used for streaming and consumer media.

Dude. You're the most. Thanks.

[ChadTower]

What if, instead of streaming a movie, I want to copy a 30 GB Bluray rip from my computer to an external drive. Or maybe I want to back up my 100 GB music collection or 2 TB video collection. Minutes vs. hours. Is USB 3.0 necessary?

USB is the wrong technology in that situation.  That person should be using an external SATA port or similar more direct connection if they need to do that with any frequency (speaking strictly of home users here). 

[ark_ader]

I'm waiting for USB 4.0 before I upgrade.