[LAU] USB, realtime, practical considerations
matt at smiffytech.com
Wed Nov 19 17:16:12 EST 2008
Whilst my 22.214.171.124-rt17 kernel and disabling all hardware and services
unneeded for audio seems to have gotten rid of those nasty xruns, I live
in fear that they will return. My main worry is how I organise my USB
My laptop (ThinkPad Z61m) has 3 USB ports. I have several devices that
need to be connected to them, meaning that I need to use USB hubs.
Here are some assumptions (or guesses) that I have made, on which I
would appreciate comment:
* It would be best to balance the devices across the 3 ports.
* My soundcard is a Behringer UCA202, capable of sampling at a maximum
of 48kHz @ 16bits x 2 channels. I'm guessing that this will have the
greatest data rate of all attached devices.
- Should it have its own port?
- Can USB 2.0 take more than this (like another device?)
- Anyone know how to set the sampling rate on this device through
Linux? Just specify in Jack setup?
* Now that I know that I can run USB to MIDI devices through a powered
hub (thanks David), I was thinking of of hooking the following into a
- iPod cable (no iPod on the end, so no burden.)
- cellphone cable (as per iPod cable.)
- external USB QWERTY keyboard (don't have desk space for this
when doing audio work, so hope it won't be transmitting any
- trackball (only transmitting when wiggled (I hope) - which should
not occur when recording is going on.)
- USB floppy drive (not in use when recording.)
- USB to MIDI interface
- Another USB to MIDI interface - is it too much to have 2 of
these on the same hub? If not, would it take a third?
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