Android13添加AudioControl接口

概述

AudioControl 模块是 Android Automotive 平台的一部分，它提供了对车载音频系统的控制接口。该模块负责管理音频路由、音量调节、音频焦点管理等功能，确保在车载环境中音频体验的流畅性和一致性。AudioControl 模块通常通过硬件抽象层（HAL）实现，与底层音频硬件通信，以执行各种音频操作。

模块架构

AudioControl 模块是基于 Android HAL 的一部分，其架构设计如下：

应用层（Application Layer）：车载应用程序通过 CarAudioManager 发起音频请求，例如播放媒体、语音助手等。
框架层（Framework Layer）：Android 框架通过 Car Audio Service 接受音频请求并将其传递到 Audio HAL。
硬件抽象层（HAL）：AudioControl 模块作为 HAL 的一部分，实现了 IAudioControl 接口，负责将来自框架的音频请求翻译成硬件可执行的操作。
硬件层（Hardware Layer）：音频硬件接收并执行 HAL 提供的指令，实现实际的音频输出和控制。

`IAudioControl` 接口

IAudioControl 接口是 AudioControl 模块的核心接口，它定义了一系列方法来控制和管理车载音频。该接口通常通过 AIDL（Android Interface Definition Language）或 HIDL（HAL Interface Definition Language）定义。以下是一些常见的方法：

onAudioFocusChange(int usage, int zoneId, int focusChange)：处理音频焦点的变化。音频焦点用于管理不同音频源之间的优先级和混音策略。
onDevicesToMuteChange(MutingInfo[] mutingInfos)：静音或取消静音特定音频设备，例如在导航提示或警报音播放时静音媒体音频。
onDevicesToDuckChange(DuckingInfo[] duckingInfos)：在某些特定事件发生时（如导航提示、电话来电等），对特定音频设备（如音乐播放设备）进行音量降低的操作。
setBalanceTowardRight(float balance)：设置左右声道的平衡。
setFadeTowardFront(float fade)：设置前后声场的淡入淡出。

这些接口方法通常是 oneway 的，这意味着它们是异步的，不会阻塞调用线程。具体的实现由 HAL 驱动和车载音频硬件共同完成。

功能和特点

AudioControl 模块的功能特点包括：

音频路由控制：根据音频类型和车载环境动态路由音频信号到正确的输出设备，例如将导航提示音发送到驾驶座的扬声器，而不是后座。
音频焦点管理：管理多个音频源的焦点请求和冲突，以确保重要的音频内容不会被其他音频打断。
设备静音和音量控制：提供对车载音频设备的静音和音量控制，以适应不同的驾驶场景和用户偏好。
自定义音频策略：支持车载厂商和应用开发者定义和实现自定义音频策略，以满足特定车辆或市场的需求。

目录结构

hardware/interfaces/automotive/audiocontrol/
├── 1.0
├── 2.0
└── aidl
    ├── aidl_api
    │   └── android.hardware.automotive.audiocontrol
    │       ├── 1
    │       ├── 2
    │       └── current
    ├── android
    ├── Android.bp
    ├── default
    └── vts

Android13 使用的是 AIDL, 没有使用 1.0 和 2.0 版本的 HIDL 。

AIDL 文件定义：IAudioControl.aidl 文件定义了 HAL 接口的规范，位于 hardware/interfaces/automotive/audiocontrol/aidl/android/hardware/automotive/audiocontrol/ 目录下。

添加接口

diff --git a/automotive/audiocontrol/aidl/android/hardware/automotive/audiocontrol/IAudioControl.aidl b/automotive/audiocontrol/aidl/android/hardware/automotive/audiocontrol/IAudioControl.aidl
index 0ffcd5e..8a5c294 100644
--- a/automotive/audiocontrol/aidl/android/hardware/automotive/audiocontrol/IAudioControl.aidl
+++ b/automotive/audiocontrol/aidl/android/hardware/automotive/audiocontrol/IAudioControl.aidl
@@ -183,4 +183,5 @@ interface IAudioControl {
      *                 interface.
      */
     oneway void registerGainCallback(in IAudioGainCallback callback);
+    oneway void setBalance(in int value);
 }
diff --git a/automotive/audiocontrol/aidl/default/AudioControl.cpp b/automotive/audiocontrol/aidl/default/AudioControl.cpp
index a121f8b..36074d0 100644
--- a/automotive/audiocontrol/aidl/default/AudioControl.cpp
+++ b/automotive/audiocontrol/aidl/default/AudioControl.cpp
@@ -214,6 +214,11 @@ binder_status_t AudioControl::dump(int fd, const char** args, uint32_t numArgs)
     }
 }
 
+ndk::ScopedAStatus AudioControl::setBalance(int in_value) {
+    LOG(DEBUG) << ": " << __func__ << "in_value: " << in_value;
+    // TODO： Implement setBalance
+    return ndk::ScopedAStatus::ok();
+}
+
 binder_status_t AudioControl::dumpsys(int fd) {
     if (mFocusListener == nullptr) {
         dprintf(fd, "No focus listener registered\n");
diff --git a/automotive/audiocontrol/aidl/default/AudioControl.h b/automotive/audiocontrol/aidl/default/AudioControl.h
index 16b80e8..bfe2780 100644
--- a/automotive/audiocontrol/aidl/default/AudioControl.h
+++ b/automotive/audiocontrol/aidl/default/AudioControl.h
@@ -54,6 +54,8 @@ class AudioControl : public BnAudioControl {
 
     binder_status_t dump(int fd, const char** args, uint32_t numArgs) override;
 
+    ndk::ScopedAStatus setBalance(int in_value) override;
+
   private:
     // This focus listener will only be used by this HAL instance to communicate with
     // a single instance of CarAudioService. As such, it doesn't have explicit serialization.

更新&编译

m android.hardware.automotive.audiocontrol-update-api
cd hardware/interfaces/automotive/audiocontrol/aidl/aidl_api/android.hardware.automotive.audiocontrol
cp -rf current/* 2/
cd -
mmm hardware/interfaces/automotive/audiocontrol/aidl

报错

[  0% 9/1305] Verify hardware/interfaces/automotive/audiocontrol/aidl/aidl_api/android.hardware.automotive.audiocontrol/2 files have not been modified
FAILED: out/soong/.intermediates/hardware/interfaces/automotive/audiocontrol/aidl/android.hardware.automotive.audiocontrol-api/checkhash_2.timestamp
if [ $(cd 'hardware/interfaces/automotive/audiocontrol/aidl/aidl_api/android.hardware.automotive.audiocontrol/2' && { find ./ -name "*.aidl" -print0 | LC_ALL=C sort -z | xargs -0 sha1sum && echo 1; } | sha1sum | cut -d " " -f 1) = $(tail -1 'hardware/interfaces/automotive/audiocontrol/aidl/aidl_api/android.hardware.automotive.audiocontrol/2/.hash') ]; then touch out/soong/.intermediates/hardware/interfaces/automotive/audiocontrol/aidl/android.hardware.automotive.audiocontrol-api/checkhash_2.timestamp; else cat 'system/tools/aidl/build/message_check_integrity.txt' && exit 1; fi
###############################################################################
# ERROR: Modification detected of stable AIDL API file                        #
###############################################################################
Above AIDL file(s) has changed, resulting in a different hash. Hash values may
be checked at runtime to verify interface stability. If a device is shipped
with this change by ignoring this message, it has a high risk of breaking later
when a module using the interface is updated, e.g., Mainline modules.
13:59:48 ninja failed with: exit status 1

#### failed to build some targets (18 seconds) ####

解决方法

获取当前 api 的 hash 并更新到 .hash 文件，然后重新编译

cd 'hardware/interfaces/automotive/audiocontrol/aidl/aidl_api/android.hardware.automotive.audiocontrol/2' && { find ./ -name "*.aidl" -print0 | LC_ALL=C sort -z | xargs -0 sha1sum && echo 1; } | sha1sum | cut -d " " -f 1 > .hash
cd -
mmm hardware/interfaces/automotive/audiocontrol/aidl

上层使用接口添加

diff --git a/service/src/com/android/car/audio/hal/AudioControlWrapper.java b/service/src/com/android/car/audio/hal/AudioControlWrapper.java
index f819cf0..18cd2ce 100644
--- a/service/src/com/android/car/audio/hal/AudioControlWrapper.java
+++ b/service/src/com/android/car/audio/hal/AudioControlWrapper.java
@@ -120,6 +120,8 @@ public interface AudioControlWrapper {
      */
     void setBalanceTowardRight(float value);

+    void setBalance(int value);
+
     /**
      * Notifies HAL of changes in usages holding focus and the corresponding ducking changes for a
      * given zone.
diff --git a/service/src/com/android/car/audio/hal/AudioControlWrapperAidl.java b/service/src/com/android/car/audio/hal/AudioControlWrapperAidl.java
index e299fe8..a7c0190 100644
--- a/service/src/com/android/car/audio/hal/AudioControlWrapperAidl.java
+++ b/service/src/com/android/car/audio/hal/AudioControlWrapperAidl.java
@@ -197,6 +197,15 @@ public final class AudioControlWrapperAidl implements AudioControlWrapper, IBind
     }

     @Override
+    public void setBalance(int value) {
+        try {
+            mAudioControl.setBalance(value);
+        } catch (RemoteException e) {
+            Slogf.e(TAG, "setBalance with " + value + " failed", e);
+        }
+    }
+
+    @Override
     public void onDevicesToDuckChange(@NonNull List<CarDuckingInfo> carDuckingInfos) {
         Objects.requireNonNull(carDuckingInfos);
         DuckingInfo[] duckingInfos = new DuckingInfo[carDuckingInfos.size()];
diff --git a/service/src/com/android/car/audio/hal/AudioControlWrapperV1.java b/service/src/com/android/car/audio/hal/AudioControlWrapperV1.java
index d0be1cb..80a67a5 100644
--- a/service/src/com/android/car/audio/hal/AudioControlWrapperV1.java
+++ b/service/src/com/android/car/audio/hal/AudioControlWrapperV1.java
@@ -124,6 +124,11 @@ public final class AudioControlWrapperV1 implements AudioControlWrapper {
     }

     @Override
+    public void setBalance(int value) {
+        Slogf.e(TAG, "setBalance impl not use, the version");
+    }
+
+    @Override
     public void onDevicesToDuckChange(List<CarDuckingInfo> carDuckingInfos) {
         throw new UnsupportedOperationException("HAL ducking is unsupported for IAudioControl@1.0");
     }
diff --git a/service/src/com/android/car/audio/hal/AudioControlWrapperV2.java b/service/src/com/android/car/audio/hal/AudioControlWrapperV2.java
index a62f4b0..75473cb 100644
--- a/service/src/com/android/car/audio/hal/AudioControlWrapperV2.java
+++ b/service/src/com/android/car/audio/hal/AudioControlWrapperV2.java
@@ -157,6 +157,11 @@ public final class AudioControlWrapperV2 implements AudioControlWrapper {
     }

     @Override
+    public void setBalance(int value) {
+        Slogf.e(TAG, "setBalance impl not use, the version");
+    }
+
+    @Override
     public void onDevicesToDuckChange(List<CarDuckingInfo> carDuckingInfos) {
         throw new UnsupportedOperationException("HAL ducking is unsupported for IAudioControl@2.0");
     }

上篇ubuntu搭建vscode阅读android_car_java环境

下篇Android13添加CarAudioManager接口

概述