Android USB isochronous data transfer

I have written a Java class for USB isochronous data transfer under Android (or Linux): UsbIso

It uses JNA to access the USBFS API via IOCTL calls.

You "can" do it without root, I believe.

You'll need to do it all using some native C code interfacing with the USB device using USBFS. The big issue comes from the lack of documentation of linux's usbfs. Basically everything has to be done through ioctls. That said you do open a device as you would normally from Java. Then you pass the file descriptor from the USBDeviceConnection

Add to that you will need to parse all the USB descriptors yourself. You can get at them, again from the USBDeviceConnection. Jumping from descriptor to descriptor is simple finding the documentation for what each descriptor means is a MASSIVE headache but you can find most of the documentation on www.usb.org.

I've written most of the code that is required to do the parsing for audio devices and I got all the way up to trying to submit an isochronous transfer and then started getting errors.

After switching to libusb I discovered that the problem, in my case, was because the audio device also had HID controllers and the default driver was atatching to those and stealing all the bandwidth away from the isochronous transfer. Had I known this earlier I might have persevered with the non-root non-libusb method. As it was I did get isochronous transfers working through lib usb but it required a rooted device :(

At some point I'll go back to it.

In summary, I'm pretty sure its possible but its not gonna be easy!!