title: When developing on Android, how can I interface with USB DAC without preventing other applications from playing sound on it?
body: <p>I have a headphone that connect to my phone via type-c. It has USB DAC in it, connected to type-c with USB protocol.</p>
  <p>To control its sidetone volume, I do:</p>
  <pre><code>        UsbInterface usbInterface = theDevice.getInterface(0);
          UsbDeviceConnection connection = usbManager.openDevice(theDevice);
          connection.claimInterface(usbInterface, true);
          byte[] buffer = intTo2Bytes(volume);
          connection.controlTransfer(0x21,0x01,0x0100,0x0200,new byte[]{0x00},1,100);
          connection.controlTransfer(0x21,0x01,0x0200,0x0200,buffer,2,100);
          connection.controlTransfer(0x21,0x01,0x0100,0x0500,new byte[]{0x00},1,100);
          connection.controlTransfer(0x21,0x01,0x0201,0x0500,new byte[]{0x00,0x00},2,100);
          connection.controlTransfer(0x21,0x01,0x0202,0x0500,new byte[]{0x00,0x00},2,100);
          connection.releaseInterface(usbInterface);
          connection.close();
  </code></pre>
  <p>I captured those addresses and commands on my USB port via wireshark, when I connect the headset to my Windows laptop and change the sidetone volume via setting. They works, as I can hear my voice in my headset.<br />
  But after I do that, other applications are not able to play sound on this device.<br />
  <strong>How can I change sidetone volume like showed above (or with other API in case I didnt know them) and still let the sound play properly?</strong></p>
  <p>Any protential help appreciated.</p>