audio_policy.conf

# Global configuration section: lists input and output devices always present on the device
# as well as the output device selected by default.
# Devices are designated by a string that corresponds to the enum in audio.h

global_configuration {
  attached_output_devices AUDIO_DEVICE_OUT_SPEAKER
  default_output_device AUDIO_DEVICE_OUT_SPEAKER
  attached_input_devices AUDIO_DEVICE_IN_BUILTIN_MIC
}

# audio hardware module section: contains descriptors for all audio hw modules present on the
# device. Each hw module node is named after the corresponding hw module library base name.
# For instance, "primary" corresponds to audio.primary.<device>.so.
# The "primary" module is mandatory and must include at least one output with
# AUDIO_OUTPUT_FLAG_PRIMARY flag.
# Each module descriptor contains one or more output profile descriptors and zero or more
# input profile descriptors. Each profile lists all the parameters supported by a given output
# or input stream category.
# The "channel_masks", "formats", "devices" and "flags" are specified using strings corresponding
# to enums in audio.h and audio_policy.h. They are concatenated by use of "|" without space or "\n".

audio_hw_modules {
  primary {
    outputs {
      primary {
        sampling_rates 44100
        channel_masks AUDIO_CHANNEL_OUT_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_SPEAKER|AUDIO_DEVICE_OUT_WIRED_HEADSET|AUDIO_DEVICE_OUT_WIRED_HEADPHONE|AUDIO_DEVICE_OUT_ALL_SCO|AUDIO_DEVICE_OUT_ANLG_DOCK_HEADSET|AUDIO_DEVICE_OUT_DGTL_DOCK_HEADSET
        flags AUDIO_OUTPUT_FLAG_PRIMARY
      }
    }
    inputs {
      primary {
        sampling_rates 8000|11025|16000|22050|24000|32000|44100|48000
        channel_masks AUDIO_CHANNEL_IN_MONO|AUDIO_CHANNEL_IN_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_IN_BUILTIN_MIC|AUDIO_DEVICE_IN_BLUETOOTH_SCO_HEADSET|AUDIO_DEVICE_IN_WIRED_HEADSET|AUDIO_DEVICE_IN_ANLG_DOCK_HEADSET|AUDIO_DEVICE_IN_DGTL_DOCK_HEADSET
      }
    }
  }
  a2dp {
    outputs {
      a2dp {
        sampling_rates 44100
        channel_masks AUDIO_CHANNEL_OUT_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_ALL_A2DP
      }
    }
  }
  hdmi {
    outputs {
      stereo {
        sampling_rates 44100|48000
        channel_masks AUDIO_CHANNEL_OUT_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_AUX_DIGITAL
      }
      multichannel {
        sampling_rates 44100|48000
        channel_masks dynamic
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_AUX_DIGITAL
        flags AUDIO_OUTPUT_FLAG_DIRECT
      }
    }
  }
  usb {
    outputs {
      usb_accessory {
        sampling_rates 44100
        channel_masks AUDIO_CHANNEL_OUT_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_USB_ACCESSORY
      }
      usb_device {
        sampling_rates 44100
        channel_masks AUDIO_CHANNEL_OUT_STEREO
        formats AUDIO_FORMAT_PCM_16_BIT
        devices AUDIO_DEVICE_OUT_USB_DEVICE
      }
    }
  }
}

mixer_paths.xml

<mixer>
  <!-- These are the initial mixer settings -->
  <ctl name="Speaker Switch" value="1" />
  <ctl name="Int Mic Switch" value="0" />
  <ctl name="Int Spk Switch" value="0" />
  <ctl name="Headphone Jack Switch" value="0" />
  <ctl name="Mic Jack Switch" value="0" />
  <ctl name="Right Speaker Mixer DACR Switch" value="1"/>
  <ctl name="Left Speaker Mixer DACL Switch" value="1"/>
  <ctl name="HPF Switch" value="0"/>
  <ctl name="Right ADC Input" value="ADC"/>
  <ctl name="Left ADC Input" value="ADC"/>
  <ctl name="Digital Capture Volume" value="96"/>
  <ctl name="DRC Switch" value="0"/>

  <path name="speaker">
    <ctl name="Int Spk Switch" value="1" />
    <ctl name="Headphone Jack Switch" value="0" />
  </path>

  <path name="headphone">
    <ctl name="Int Spk Switch" value="0" />
    <ctl name="Headphone Jack Switch" value="1" />
    <ctl name="Right Speaker Mixer DACR Switch" value="0"/>
    <ctl name="Left Speaker Mixer DACL Switch" value="0"/>
  </path>
  
  <path name="hdmi">
    <ctl name="Speaker Switch" value="0" />
  </path>

  <path name="main-mic-top">
    <ctl name="Int Mic Switch" value="1" />
    <ctl name="HPF Switch" value="1"/>
    <ctl name="Right ADC Input" value="DMIC"/>
    <ctl name="Left ADC Input" value="DMIC"/>
    <ctl name="DRC Switch" value="1"/>
  </path>

  <path name="main-mic-left">
    <ctl name="Int Mic Switch" value="1" />
    <ctl name="HPF Switch" value="1"/>
    <ctl name="Right ADC Input" value="DMIC"/>
    <ctl name="Left ADC Input" value="DMIC"/>
    <ctl name="DRC Switch" value="1"/>
  </path>

  <path name="headset-mic">
    <ctl name="Mic Jack Switch" value="1" />
  </path>
</mixer>