Ralf Mardorf wrote: > On Mon, 2014-08-04 at 23:11 +0400, Vladimir Mosgalin wrote: >>> IIRC the plug'n'play audio USB driver is limited to USB1, for USB2 >>> proprietary drivers are needed. >> >> Can't be true.. Here is example of USB 2.0 audio device (bcdUSB: 2.00), >> completely plug and play: > > Perhaps the devices aren't recognised as 2.0 devices. I don't know how > much channels duplex for unsynced USB devices do work sharing one USB, > USB 1 or 2. An expert should chime in. Does "2.0 full speed-compatible" > mean "USB-2 class compliant" or is a special driver needed?
USB 2.0 is not the same as as USB Audio 2. (USB 2.0 adds the high-speed mode, i.e., 480 Mbit/s. USB Audio 2 is a specification that allows conformant drivers and USB 2 devices to work together.) Nowadays, Linux does support USB Audio 2. (As do OS X, and FreeBSD; the only holdout is Windows.) >>> perhaps the bandwidth really is to small. Indeed, that is why the error message says "bandwidth". Please note that USB 2.0 *adds* high speed mode, so it is still possible to have devices running at full speed (12 Mbit/s). Bandwidth is measured in time, not bits, so a bit from a full-speed device takes as much bandwidth as 40 bits from a high-speed device. A single stereo full-duplex device can easily max out a full-speed bus. If you want to use two of them, connect them to *different* buses. (Check the output of "lsusb -t" to see which bus they are connected to.) Regards, Clemens ------------------------------------------------------------------------------ Infragistics Professional Build stunning WinForms apps today! Reboot your WinForms applications with our WinForms controls. Build a bridge from your legacy apps to the future. http://pubads.g.doubleclick.net/gampad/clk?id=153845071&iu=/4140/ostg.clktrk _______________________________________________ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
