[sdiy] USB and the art of MIDI

[Florian E. Teply]

ASSI schrieb:
> On Samstag 19 April 2008, Batz Goodfortune wrote:
>> Y-ellow Humans.
>>          I'm wondering if anyone here has tried those little, Cheap,
>> Chinese USB to MIDI adaptors? More specifically, has anyone tried
>> using 2 or more out of a hub at the same time?
> 
> That should work in principle, but I'd rather use a USB2.0 high-speed 
> hub if more than four MIDI interfaces are in use at full bore.
> 
>> Even more specifically, I'm wondering if it might be possible to make
>> an ad-hock, expandable, multi-MIDI interface with say 10 or more
>> I/Os. I'm not worried about the electrical limitations. IE: Power
>> consumption and so fourth. I can take care of that with suitable
>> hacks. All I'm interested in is if the computer would see multiple
>> individual MIDI interfaces or get thoroughly confused and see them
>> all as just one single MIDI interface. Or something in between?
> 
> Depends on what you mean by "computer".  With a modern Linux I don't see 
> any problem, and all interfaces should show up as seperate devices 
> (they may have multiple ports).  Getting them to always use the same 
> device name and MIDI port number in ALSA will be a bit tricky however, 
> normally they will show up in the order they are found during device 
> discovery.  MIDI interfaces which need a driver downloaded at each 
> plug-in also often require manual configuration, but class-compliant 
> interfaces just work.  If the USB descriptors are halfway 
> spec-compliant each interface is listed with the name given by the 
> manufacturer so it is relatively easy to tell them apart.
> 
Well, the device naming (device names being the same after reboot, with 
names just as you like 'em) is a non-issue with udev, wich nowadays 
controls most devices. Usually, each device has some sort of unique 
identifier (MAC Address on ethernet cards or hard coded serial number 
for example). With that information udev can rearrange device names 
automagically with proper configuration.

I don't recall how to configure this right now though, but could look it 
up if needed.

Greetings
Florian