Android9.0AudioPolicy之audio_policy_configuration.xml解析(二)

前言

之前通过代码说了audio_policy_configuration的解析过程，代码确实需要一定耐心来看，那么今天结合具体xml再来说明下audio_policy_configuration的解析过程

正文

audio_policy_configuration.xml位于frameworks/av/services/audiopolicy/config/ 目录下

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- 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.
-->

<audioPolicyConfiguration version="1.0" xmlns:xi="http://www.w3.org/2001/XInclude">
    <!-- version section contains a “version” tag in the form “major.minor” e.g version=”1.0” -->

    <!-- Global configuration Decalaration -->
    <globalConfiguration speaker_drc_enabled="true"/>


    <!-- Modules section:
        There is one section per audio HW module present on the platform.
        Each module section will contains two mandatory tags for audio HAL “halVersion” and “name”.
        The module names are the same as in current .conf file:
                “primary”, “A2DP”, “remote_submix”, “USB”
        Each module will contain the following sections:
        “devicePorts”: a list of device descriptors for all input and output devices accessible via this
        module.
        This contains both permanently attached devices and removable devices.
        “mixPorts”: listing all output and input streams exposed by the audio HAL
        “routes”: list of possible connections between input and output devices or between stream and
        devices.
            "route": is defined by an attribute:
                -"type": <mux|mix> means all sources are mutual exclusive (mux) or can be mixed (mix)
                -"sink": the sink involved in this route
                -"sources": all the sources than can be connected to the sink via vis route
        “attachedDevices”: permanently attached devices.
        The attachedDevices section is a list of devices names. The names correspond to device names
        defined in <devicePorts> section.
        “defaultOutputDevice”: device to be used by default when no policy rule applies
    -->
    <modules>
        <!-- Primary Audio HAL -->
         <!--从module标签开始，module即对应的HwModule，对应初始化module 的name和halVersion，解析完module会通过AudioPolicyConfig的-->

        <module name="primary" halVersion="3.0">
        <!--attachedDevices是最后解析的，通过AudioPolicyConfig赋值mAvailableOutputDevices(DeviceDescriptor集合)和mAvailableInputDevices(DeviceDescriptor集合) -->

            <attachedDevices>
                <item>Speaker</item>
                <item>Built-In Mic</item>
                <item>Built-In Back Mic</item>
            </attachedDevices>
            <!--defaultOutputDevice也是最后解析的，通过AudioPolicyConfig赋值mDefaultOutputDevices(DeviceDescriptor) -->

            <defaultOutputDevice>Speaker</defaultOutputDevice>
            <!-- 找到module标签后便首先开始解析mixport，将所有的mixport作为集合赋值给module下的mInputProfiles(IOProfile集合)和mOutputProfiles(IOProfile集合)
            和mPorts(AudioPort集合)-->
            <mixPorts>
                <!-- 每一个mixrort就是一个IOProfile即AudioPort，对应初始化name和falgs属性，以及根据role属性判断是加入mInputProfiles或mOutputProfiles中
                将所有的profile作为集合赋值给mixPort下的mProfiles-->
                <mixPort name="primary output" role="source" flags="AUDIO_OUTPUT_FLAG_PRIMARY">
                <!-- 每一个profile 就是一个IOProfile即AudioProfile，对应初始化format samplingRates 和channelMasks-->
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
                </mixPort>
                
                <mixPort name="deep_buffer" role="source"
                        flags="AUDIO_OUTPUT_FLAG_DEEP_BUFFER">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
                </mixPort>
                <mixPort name="compressed_offload" role="source"
                         flags="AUDIO_OUTPUT_FLAG_DIRECT|AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD|AUDIO_OUTPUT_FLAG_NON_BLOCKING">
                    <profile name="" format="AUDIO_FORMAT_MP3"
                             samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000"
                             channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/>
                    <profile name="" format="AUDIO_FORMAT_AAC"
                             samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000"
                             channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/>
                    <profile name="" format="AUDIO_FORMAT_AAC_LC"
                             samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000"
                             channelMasks="AUDIO_CHANNEL_OUT_STEREO,AUDIO_CHANNEL_OUT_MONO"/>
                </mixPort>
                <mixPort name="voice_tx" role="source">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/>
                </mixPort>
                <mixPort name="primary input" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000"
                             channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/>
                </mixPort>
                <mixPort name="voice_rx" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_IN_MONO"/>
                </mixPort>
            </mixPorts>
            <!--解析devicePort 标签通过HwModule初始化mDeclaredDevices(DeviceDescriptor集合)和mPorts(AudioPort集合)-->
            <devicePorts>
                <!-- Output devices declaration, i.e. Sink DEVICE PORT -->
                <devicePort tagName="Earpiece" type="AUDIO_DEVICE_OUT_EARPIECE" role="sink">
                   <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                            samplingRates="48000" channelMasks="AUDIO_CHANNEL_IN_MONO"/>
                </devicePort>
                <devicePort tagName="Speaker" role="sink" type="AUDIO_DEVICE_OUT_SPEAKER" address="">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
                    <gains>
                        <gain name="gain_1" mode="AUDIO_GAIN_MODE_JOINT"
                              minValueMB="-8400"
                              maxValueMB="4000"
                              defaultValueMB="0"
                              stepValueMB="100"/>
                    </gains>
                </devicePort>
                <devicePort tagName="Wired Headset" type="AUDIO_DEVICE_OUT_WIRED_HEADSET" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
                </devicePort>
                <devicePort tagName="Wired Headphones" type="AUDIO_DEVICE_OUT_WIRED_HEADPHONE" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
                </devicePort>
                <devicePort tagName="BT SCO" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/>
                </devicePort>
                <devicePort tagName="BT SCO Headset" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO_HEADSET" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/>
                </devicePort>
                <devicePort tagName="BT SCO Car Kit" type="AUDIO_DEVICE_OUT_BLUETOOTH_SCO_CARKIT" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/>
                </devicePort>
                <devicePort tagName="Telephony Tx" type="AUDIO_DEVICE_OUT_TELEPHONY_TX" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_OUT_MONO"/>
                </devicePort>

                <devicePort tagName="Built-In Mic" type="AUDIO_DEVICE_IN_BUILTIN_MIC" role="source">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000"
                             channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/>
                </devicePort>
                <devicePort tagName="Built-In Back Mic" type="AUDIO_DEVICE_IN_BACK_MIC" role="source">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000"
                             channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/>
                </devicePort>
                <devicePort tagName="Wired Headset Mic" type="AUDIO_DEVICE_IN_WIRED_HEADSET" role="source">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,11025,12000,16000,22050,24000,32000,44100,48000"
                             channelMasks="AUDIO_CHANNEL_IN_MONO,AUDIO_CHANNEL_IN_STEREO,AUDIO_CHANNEL_IN_FRONT_BACK"/>
                </devicePort>
                <devicePort tagName="BT SCO Headset Mic" type="AUDIO_DEVICE_IN_BLUETOOTH_SCO_HEADSET" role="source">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_IN_MONO"/>
                </devicePort>
                <devicePort tagName="Telephony Rx" type="AUDIO_DEVICE_IN_TELEPHONY_RX" role="source">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="8000,16000" channelMasks="AUDIO_CHANNEL_IN_MONO"/>
                </devicePort>
            </devicePorts>
            <!-- route declaration, i.e. list all available sources for a given sink -->
            <!-- 解析route标签赋值给HwModule的mRoutes(AudioRoute集合) 并对应初始化mixport即IOProfile的mSupportedDevices，这个对应规则可以参照
            [Android9.0AudioPolicy之audio_policy_configuration.xml解析(一)][1]-->

            <routes>
                <route type="mix" sink="Earpiece"
                       sources="primary output,deep_buffer,BT SCO Headset Mic"/>
                <route type="mix" sink="Speaker"
                       sources="primary output,deep_buffer,compressed_offload,BT SCO Headset Mic,Telephony Rx"/>
                <route type="mix" sink="Wired Headset"
                       sources="primary output,deep_buffer,compressed_offload,BT SCO Headset Mic,Telephony Rx"/>
                <route type="mix" sink="Wired Headphones"
                       sources="primary output,deep_buffer,compressed_offload,BT SCO Headset Mic,Telephony Rx"/>
                <route type="mix" sink="Telephony Tx"
                       sources="voice_tx"/>
                <route type="mix" sink="primary input"
                       sources="Built-In Mic,Built-In Back Mic,Wired Headset Mic,BT SCO Headset Mic"/>
                <route type="mix" sink="Telephony Tx"
                       sources="Built-In Mic,Built-In Back Mic,Wired Headset Mic,BT SCO Headset Mic"/>
                <route type="mix" sink="voice_rx"
                       sources="Telephony Rx"/>
            </routes>

        </module>

        <!-- HDMI Audio HAL -->
        <module description="HDMI Audio HAL" name="hdmi" version="2.0">
            <mixPorts>
                <mixPort name="hdmi output" role="source">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT" samplingRates="48000"/>
                </mixPort>
            </mixPorts>
            <devicePorts>
                <devicePort tagName="HDMI Out" type="AUDIO_DEVICE_OUT_AUX_DIGITAL" role="sink">
                    <profile name="" format="AUDIO_FORMAT_PCM_16_BIT"
                             samplingRates="48000" channelMasks="AUDIO_CHANNEL_OUT_STEREO"/>
                </devicePort>
            </devicePorts>
            <routes>
                <route type="mix" sink="HDMI Out"
                       sources="hdmi output"/>
            </routes>
        </module>

        <!-- A2dp Audio HAL -->
        <xi:include href="a2dp_audio_policy_configuration.xml"/>

        <!-- Usb Audio HAL -->
        <xi:include href="usb_audio_policy_configuration.xml"/>

        <!-- Remote Submix Audio HAL -->
        <xi:include href="r_submix_audio_policy_configuration.xml"/>

    </modules>
    <!-- End of Modules section -->

    <!-- Volume section -->

    <xi:include href="audio_policy_volumes.xml"/>
    <xi:include href="default_volume_tables.xml"/>

    <!-- End of Volume section -->

</audioPolicyConfiguration>

总结

这样整个policy的xml就解析完成了。有点需要注意这里有个

        <!-- A2dp Audio HAL -->
        <xi:include href="a2dp_audio_policy_configuration.xml"/>

        <!-- Usb Audio HAL -->
        <xi:include href="usb_audio_policy_configuration.xml"/>

        <!-- Remote Submix Audio HAL -->
        <xi:include href="r_submix_audio_policy_configuration.xml"/>

其实在解析时这些include 的文件也会放到一起解析的，下一张分享下解析完audio_policy_configuration后AudioPolicyManager又做了什么，
如有任何问题，欢迎指正