services/audiopolicy/config/usb_audio_policy_configuration.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright (C) 2015 The Android Open Source Project

     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
     You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
     limitations under the License.
-->
<!-- USB Audio HAL Audio Policy Configuration file -->

<module name="usb" halVersion="2.0">
    <mixPorts>
        <mixPort name="usb_accessory output" role="source">
            <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                     samplingRates="44100" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
        </mixPort>
        <mixPort name="usb_device output" role="source"/>
        <mixPort name="usb_device input" role="sink"/>
    </mixPorts>
    <devicePorts>
        <devicePort tagName="USB Host Out" type="AUDIO_DEVICE_OUT_USB_ACCESSORY" role="sink">
            <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                     samplingRates="44100" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
        </devicePort>
        <devicePort tagName="USB Device Out" type="AUDIO_DEVICE_OUT_USB_DEVICE" role="sink"/>
        <devicePort tagName="USB Device In" type="AUDIO_DEVICE_IN_USB_DEVICE" role="source"/>
    </devicePorts>
    <routes>
        <route type="mix" sink="USB Host Out"
               sources="usb_accessory output"/>
        <route type="mix" sink="USB Device Out"
               sources="usb_device output"/>
        <route type="mix" sink="usb_device input"
               sources="USB Device In"/>
    </routes>
</module>