Für SD capture reicht auch locker USB2. In meinem Fall mit USB3 und einer WD CMR externen Festplatte brach die Übertragungsrate kurzzeitig ein und verursachte dropped Frames. Virtual Dub hatte keine dropped Frames gemeldet da der Fehler ja beim Schreiben der Daten passierte.
Interessant sind die Beiträge von einem unseren amerikanischen Kollegen "jwillis84" im Bezug auf USB3. Ich kopier mal einen seiner Beiträge dazu hier:
"I'm biased through recent experience with Blackmagic Shuttles and USB 3.0 chipsets.
I had similar problems when using ASMedia or any brand of USB 3.0 port chipset "except" the uPD NEC 720200 USB chip.
The USB connection has a lot of problems, "especially" with USB 3.0
USB 2.0 was a very rigid specification, chip makers and motherboard makers were literally "forced" to participate in compatibility "bake off events" before they could label their products USB 2.0 and could sell them to consumers.
USB 3.0 manufacturers fought back.. and removed the "must comply with standards" edict.. it was a marketing and sales "disaster" of EPIC proportions.
(Most) motherboard manufacturers simply removed all documentation about their USB 3.0 ports and declined any technical inquiries about them.
HP and Dell "rigidly" paid extra money to buy motherboards with (one) USB 2.0 chip on one port.. so they would not get sued into oblivion. all other ports were no-name USB 3.0 ports
The problem is in the design of the cheap USB 3.0 ports.
NEC was the champion of USB 2.0 chipset design, first to market, and very compliant. When they made their USB 3.0 chips.. they did not sell well because.. they "were not cheap". So they partnered with Apple, Sonnet and very high end PCI/PCIe companies to make add-on cards with the uPD 720200 chip .. they are very compliant, compatible, industrial grade.
.. and.. they don't drop frames
There is a myth they are hard to find.. not true.. but they are not cheap.
The cards today cost around $30 for a two port uPD 720200 based card.
Now the high speeds involved mean sometimes you can get one port that works fine.. but another does not.. so be sure to not trust only one port.. and switch around to find one that does not drop frames.
On a bad port.. frame drops are fairly common.
Using AMARec 3.10 (on a good port) .. absolutely "Zero" frames should be dropped.
Its probably not a capture device problem.
Its probably a sketchy USB chipset, or bad USB port.. in manufacturing even if you have a great USB chip a bad solder job.. or weak PC board trace can cause problems"