Android13 SoundPool play流程分析

SoundPool的play方法用于播放音效文件，代码如下：

//frameworks/base/media/java/android/media/SoundPool.java
public class SoundPool extends PlayerBase {
    public final int play(int soundID, float leftVolume, float rightVolume,
            int priority, int loop, float rate) {
        // FIXME: b/174876164 implement device id for soundpool
        baseStart(0);
        return _play(soundID, leftVolume, rightVolume, priority, loop, rate);
    }
}

调用_play方法，_play是一个native方法，实现代码如下：

//frameworks/base/media/jni/soundpool/android_media_soundPool.cpp
static jint
android_media_SoundPool_play(JNIEnv *env, jobject thiz, jint sampleID,
        jfloat leftVolume, jfloat rightVolume, jint priority, jint loop,
        jfloat rate)
{
    ALOGV("android_media_SoundPool_play\n");
    auto soundPool = getSoundPool(env, thiz);
    if (soundPool == nullptr) return 0;
    return (jint) soundPool->play(sampleID, leftVolume, rightVolume, priority, loop, rate);
}

上面方法处理如下：

1、调用getSoundPool方法，获取SoundPool对象

2、调用SoundPool的play方法进行音效声音play

下面分别进行分析：

getSoundPool

调用getSoundPool方法，获取SoundPool对象：

//frameworks/base/media/jni/soundpool/android_media_soundPool.cpp
inline auto getSoundPool(JNIEnv *env, jobject thiz) {
    return getSoundPoolManager().get(env, thiz);
}

调用getSoundPoolManager方法：

//frameworks/base/media/jni/soundpool/android_media_soundPool.cpp
auto& getSoundPoolManager() {
    static ObjectManager<std::shared_ptr<SoundPool>> soundPoolManager(fields.mNativeContext);
    return soundPoolManager;
}

SoundPool play

调用SoundPool的play方法进行音效声音play：

//frameworks/base/media/jni/SoundPool/SoundPool.cpp
int32_t SoundPool::play(int32_t soundID, float leftVolume, float rightVolume,
        int32_t priority, int32_t loop, float rate)
{
    ALOGV("%s(soundID=%d, leftVolume=%f, rightVolume=%f, priority=%d, loop=%d, rate=%f)",
            __func__, soundID, leftVolume, rightVolume, priority, loop, rate);


    // New for R: check arguments to ensure track can be created.
    // If SoundPool defers the creation of the AudioTrack to the StreamManager thread,
    // the failure to create may not be visible to the caller, so this precheck is needed.
    if (checkVolume(&leftVolume, &rightVolume)
            || checkPriority(&priority)
            || checkLoop(&loop)
            || checkRate(&rate)) return 0;


    auto apiLock = kUseApiLock ? std::make_unique<std::lock_guard<std::mutex>>(mApiLock) : nullptr;
    const std::shared_ptr<soundpool::Sound> sound = mSoundManager.findSound(soundID); //通过soundID获取sound 对象
    if (sound == nullptr || sound->getState() != soundpool::Sound::READY) { //判断sound状态
        ALOGW("%s soundID %d not READY", __func__, soundID);
        return 0;
    }


    const int32_t streamID = mStreamManager.queueForPlay(
            sound, soundID, leftVolume, rightVolume, priority, loop, rate);
    ALOGV("%s returned %d", __func__, streamID);
    return streamID;
}

调用StreamManager的queueForPlay方法：

//frameworks/base/media/jni/SoundPool/StreamManager.cpp
int32_t StreamManager::queueForPlay(const std::shared_ptr<Sound> &sound,
        int32_t soundID, float leftVolume, float r