Re: Recordings Stuttering
Unfortunately I do not have a pointer to it. The short version with regards to USB 3 with attached USB 2 devices (or USB 2 with attached USB 1 or 1.1 devices) involves time rather than data rate issues.toggle quoted messageShow quoted text
Every time a lower rated USB device tries to transfer data on a higher rated hub (port) the whole bus slows down to the lower rate for the duration of the transfer. This consumes time on the bus. So a 1.1 device may consume maybe 40 times as much of the nominal bandwidth on the port. Furthermore for perceived response on your screen mice send very small messages with fairly large overhead with a payload value of 1 mouse step. It's a bit difficult to get a mouse to actually send a payload of say 42 mouse steps. So what might be a (swag alert) 3 byte transfer turns into a (swag) 15 or 20 byte handshake plus transfer all at 10 MB/S or so. That's 50 to 90 megabytes/second carved away from the nominal 400 megabytes/second on the bus. So slow devices eat your hub's capability FAST. That is why AirSpys have trouble at 10 Msps on a USB2 bus that should "easily" handle the bit packed transfer rate of an AirSpy. The full USB2 bus is seldom really there. And if you hook up to a USB 3 hub you are still stuck with the AirSpy eating 3/4 of the bus bandwidth give or take a little. Anything else on that bus, say an external drive or an internal DVD drive can cause extreme stuttering or outright failure.
(All numbers are Scientific Wild Assed Guesses rather than correct to more than 1 decimal place. The concept is what is of concern in the numbers above. If my memory serves the numbers are "close" if not exact.)
On 20210703 16:08:57, James Niven wrote: