请写一个使用NDK播放声音的例子

好的，以下是一个使用NDK播放声音的例子：

1. 首先，在Android Studio中创建一个新的NDK项目。
2. 在app / src / main / jni目录下创建一个名为audio.c的新文件。
3. 将以下代码复制并粘贴到audio.c文件中：

#include <jni.h>
#include <string.h>
#include <android/log.h>
#include <SLES/OpenSLES.h>
#include <SLES/OpenSLES_Android.h>

#define TAG "AudioPlayer"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR, TAG, __VA_ARGS__)

// 声明OpenSL ES接口
SLObjectItf engineObject = NULL;
SLEngineItf engineEngine;

SLObjectItf outputMixObject = NULL;
SLEnvironmentalReverbItf outputMixEnvironmentalReverb = NULL;
SLEnvironmentalReverbSettings reverbSettings = SL_I3DL2_ENVIRONMENT_PRESET_STONECORRIDOR;

SLObjectItf playerObject = NULL;
SLPlayItf playerPlay;
SLAndroidSimpleBufferQueueItf playerBufferQueue;

void playerCallback(SLAndroidSimpleBufferQueueItf bq, void *context) {
    LOGI("playerCallback");
}

JNIEXPORT void JNICALL
Java_com_example_audioplayer_AudioPlayer_init(JNIEnv *env, jobject instance) {
    LOGI("init");

    // 创建OpenSL ES引擎
    slCreateEngine(&engineObject, 0, NULL, 0, NULL, NULL);
    (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);
    (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineEngine);

    // 创建输出混音器
    (*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject, 0, NULL, NULL);
    (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);
    (*outputMixObject)->GetInterface(outputMixObject, SL_IID_ENVIRONMENTALREVERB, &outputMixEnvironmentalReverb);
    (*outputMixEnvironmentalReverb)->SetEnvironmentalReverbProperties(outputMixEnvironmentalReverb, &reverbSettings);

    // 创建播放器
    SLDataLocator_AndroidSimpleBufferQueue locatorBufferQueue = {SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, 2};
    SLDataFormat_PCM formatPcm = {SL_DATAFORMAT_PCM, 1, SL_SAMPLINGRATE_44_1,
                                  SL_PCMSAMPLEFORMAT_FIXED_16, SL_PCMSAMPLEFORMAT_FIXED_16,
                                  SL_SPEAKER_FRONT_CENTER, SL_BYTEORDER_LITTLEENDIAN};
    SLDataSource audioSrc = {&locatorBufferQueue, &formatPcm};
    SLDataLocator_OutputMix locatorOutputMix = {SL_DATALOCATOR_OUTPUTMIX, outputMixObject};
    SLDataSink audioSnk = {&locatorOutputMix, NULL};
    const SLInterfaceID ids[1] = {SL_IID_BUFFERQUEUE};
    const SLboolean req[1] = {SL_BOOLEAN_TRUE};
    (*engineEngine)->CreateAudioPlayer(engineEngine, &playerObject, &audioSrc, &audioSnk, 1, ids, req);
    (*playerObject)->Realize(playerObject, SL_BOOLEAN_FALSE);
    (*playerObject)->GetInterface(playerObject, SL_IID_PLAY, &playerPlay);
    (*playerObject)->GetInterface(playerObject, SL_IID_BUFFERQUEUE, &playerBufferQueue);
    (*playerBufferQueue)->RegisterCallback(playerBufferQueue, playerCallback, NULL);
}

JNIEXPORT void JNICALL
Java_com_example_audioplayer_AudioPlayer_play(JNIEnv *env, jobject instance, jbyteArray data_, jint len) {
    LOGI("play");

    // 将数据写入缓冲区
    jbyte *data = (*env)->GetByteArrayElements(env, data_, NULL);
    (*playerBufferQueue)->Clear(playerBufferQueue);
    (*playerBufferQueue)->Enqueue(playerBufferQueue, data, len);
    (*env)->ReleaseByteArrayElements(env, data_, data, 0);

    // 开始播放
    (*playerPlay)->SetPlayState(playerPlay, SL_PLAYSTATE_PLAYING);
}

JNIEXPORT void JNICALL
Java_com_example_audioplayer_AudioPlayer_stop(JNIEnv *env, jobject instance) {
    LOGI("stop");

    // 停止播放
    (*playerPlay)->SetPlayState(playerPlay, SL_PLAYSTATE_STOPPED);

    // 销毁播放器
    if (playerObject != NULL) {
        (*playerObject)->Destroy(playerObject);
        playerObject = NULL;
        playerPlay = NULL;
        playerBufferQueue = NULL;
    }

    // 销毁输出混音器
    if (outputMixObject != NULL) {
        (*outputMixObject)->Destroy(outputMixObject);
        outputMixObject = NULL;
        outputMixEnvironmentalReverb = NULL;
    }

    // 销毁OpenSL ES引擎
    if (engineObject != NULL) {
        (*engineObject)->Destroy(engineObject);
        engineObject = NULL;
        engineEngine = NULL;
    }
}

4. 在app / src / main / java目录下创建一个名为AudioPlayer.java的新文件，并将以下代码复制并粘贴到其中：

package com.example.audioplayer;

public class AudioPlayer {
    static {
        System.loadLibrary("audio");
    }

    public native void init();

    public native void play(byte[] data, int len);

    public native void stop();
}

5. 现在可以在您的应用程序中使用AudioPlayer类来播放声音了。在您的Android应用程序中，创建一个新的AudioPlayer对象并调用init方法来初始化OpenSL ES引擎。然后，使用play方法将PCM音频数据写入缓冲区并开始播放，使用stop方法停止播放并销毁OpenSL ES引擎。

这个例子可能还需要一些改进，比如添加错误处理和音频数据的缓冲等。但这应该可以帮助您入门使用NDK播放声音。