Hi Everyone,

I'm trying to use two audio interfaces (Guitar Link UC6102) in parallel in Alsa on a UDOO board that runs Ubuntu. The two interfaces are connected on the two USB 2.0 port available on the board: I'm not using any hub. In 20% of the cases, this works fine and I'm able to use the two interface as one single "virtual" interface with 4 inputs and 4 outputs (see my .asoundrc file bellow). However, in 80% of the cases, this doesn't work and dmesg says: "cannot submit datapipe for urb 0, error -28: not enough bandwidth".

Any idea of where this problem comes from? I can use 4 of these interfaces on the same USB port with a hub on my laptop without any problem...

Thanks for your help :)

Cheers,

Romain

.asoundrc:

pcm.myMAIN {
type route;
slave.pcm {
      type multi;
      slaves.a.pcm "myOUT0";
      slaves.b.pcm "myOUT1";
      slaves.a.channels 2;
      slaves.b.channels 2;
      bindings.0.slave a;
      bindings.0.channel 0;
      bindings.1.slave a;
      bindings.1.channel 1;

      bindings.2.slave b;
      bindings.2.channel 0;
      bindings.3.slave b;
      bindings.3.channel 1;
}

ttable.0.0 1;
ttable.1.1 1;
ttable.2.2 1;
ttable.3.3 1;
#ttable.0.2 1; # front left
#ttable.1.3 1; # front right
#ttable.0.4 1; # copy front left to rear left
#ttable.1.5 1; # copy front right to rear right
}

ctl.myMAIN {
type hw;
card CODEC;
}

pcm.builtIn {
    type hw
    card vt1613audio
}

ctl.builtIn {
    type hw
    card vt1613audio
}

pcm.myOUT0 {
    type hw
    card CODEC
}

ctl.myOUT0 {
    type hw
    card CODEC
}

pcm.myOUT1 {
    type hw
    card CODEC_1
}

ctl.myOUT1 {
    type hw
    card CODEC_1
}

Romain Michon
PhD Candidate
Center for Computer Research in Music and Acoustics
Stanford University
http://ccrma.stanford.edu/~rmichon