android使用opensl es进行简单的音频播放

OpenSL ES 全称是：Open Sound Library for Embedded Systems，是一套无授权费、跨平台、针对嵌入式系统精心优化的硬件音频加速API。它为嵌入式移动多媒体设备上的本地应用程序开发者提供标准化, 高性能, 低响应时间的音频功能实现方法，并实现软硬件音频性能的直接跨平台部署，降低android执行难度，促进高级音频市场的发展。

在android系统中是自带了opensl es的so库的，所以我们只需要在CMakeLists中链接以下就可以了，在引入头文件

#include <SLES/OpenSLES.h>
#include <SLES/OpenSLES_Android.h>

声明native方法

//设置播放状态
public  native void setPlayingAssetAudioPlayer(boolean isPlaying);
//释放资源
public  native void shutdown();
//创建引擎
public native void createEngine();
//播放  assets对象，文件名
public native boolean player(AssetManager assetManager, String filename);

extern "C"
JNIEXPORT void JNICALL
Java_com_xiukun_lxkaudio_MainActivity_createEngine(JNIEnv *env, jobject instance) {

// TODO
SLresult result;
//初始化引擎
slCreateEngine(&engineObject,0,NULL,0,NULL,NULL);

(*engineObject)->Realize(engineObject,SL_BOOLEAN_FALSE);
//获取引擎接口
(*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineEngine);

//创建音频输出，配置相关参数
const SLInterfaceID ids[1] = {SL_IID_ENVIRONMENTALREVERB};
const SLboolean req[1] = {SL_BOOLEAN_FALSE};
(*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject, 1, ids, req);

(*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);

//环境混响
result = (*outputMixObject)->GetInterface(outputMixObject, SL_IID_ENVIRONMENTALREVERB,
&outputMixEnvironmentalReverb);
if (SL_RESULT_SUCCESS == result) {
(*outputMixEnvironmentalReverb)->SetEnvironmentalReverbProperties(
outputMixEnvironmentalReverb, &reverbSettings);
}

}

extern "C"
JNIEXPORT jboolean JNICALL
Java_com_xiukun_lxkaudio_MainActivity_player(JNIEnv *env, jobject instance, jobject assetManager,
jstring filename_) {
const char *filename = env->GetStringUTFChars(filename_, 0);

// TODO
// 读取assets文件
AAssetManager* mgr = AAssetManager_fromJava(env, assetManager);
AAsset* asset = AAssetManager_open(mgr, filename, AASSET_MODE_UNKNOWN);

if (NULL == asset) {
LOGE("读取失败。。。");
return JNI_FALSE;
}

// open asset as file descriptor
off_t start, length;
int fd = AAsset_openFileDescriptor(asset, &start, &length);
AAsset_close(asset);

// 配置信息
SLDataLocator_AndroidFD loc_fd = {SL_DATALOCATOR_ANDROIDFD, fd, start, length};
SLDataFormat_MIME format_mime = {SL_DATAFORMAT_MIME, NULL, SL_CONTAINERTYPE_UNSPECIFIED};
SLDataSource audioSrc1 = {&loc_fd, &format_mime};

// configure audio sink
SLDataLocator_OutputMix loc_outmix1 = {SL_DATALOCATOR_OUTPUTMIX, outputMixObject};
SLDataSink audioSnk1 = {&loc_outmix1, NULL};

// 创建播放器
const SLInterfaceID audio_ids1[3] = {SL_IID_SEEK, SL_IID_MUTESOLO, SL_IID_VOLUME};
const SLboolean audio_req1[3] = {SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE};

(*engineEngine)->CreateAudioPlayer(engineEngine, &fdPlayerObject, &audioSrc1, &audioSnk1,
3, audio_ids1, audio_req1);

(*fdPlayerObject)->Realize(fdPlayerObject, SL_BOOLEAN_FALSE);

// 获取播放器接口
(*fdPlayerObject)->GetInterface(fdPlayerObject, SL_IID_PLAY, &fdPlayerPlay);

// 定位
(*fdPlayerObject)->GetInterface(fdPlayerObject, SL_IID_SEEK, &fdPlayerSeek);

// 静音独奏
(*fdPlayerObject)->GetInterface(fdPlayerObject, SL_IID_MUTESOLO, &fdPlayerMuteSolo);

// 音量
(*fdPlayerObject)->GetInterface(fdPlayerObject, SL_IID_VOLUME, &fdPlayerVolume);

// 开启重复播放
(*fdPlayerSeek)->SetLoop(fdPlayerSeek, SL_BOOLEAN_TRUE, 0, SL_TIME_UNKNOWN);

env->ReleaseStringUTFChars(filename_, filename);

return JNI_TRUE;
}

extern "C"
JNIEXPORT void JNICALL
Java_com_xiukun_lxkaudio_MainActivity_setPlayingAssetAudioPlayer(JNIEnv *env, jobject instance,
jboolean isPlaying) {

//设置播放状态
if (NULL != fdPlayerPlay) {

(*fdPlayerPlay)->SetPlayState(fdPlayerPlay, isPlaying ?
SL_PLAYSTATE_PLAYING : SL_PLAYSTATE_PAUSED);
}

}

extern "C"
JNIEXPORT void JNICALL
Java_com_xiukun_lxkaudio_MainActivity_shutdown(JNIEnv *env, jobject instance) {

if (fdPlayerObject != NULL) {
(*fdPlayerObject)->Destroy(fdPlayerObject);
fdPlayerObject = NULL;
fdPlayerPlay = NULL;
fdPlayerSeek = NULL;
fdPlayerMuteSolo = NULL;
fdPlayerVolume = NULL;
}

// destroy output mix object, and invalidate all associated interfaces
if (outputMixObject != NULL) {
(*outputMixObject)->Destroy(outputMixObject);
outputMixObject = NULL;
outputMixEnvironmentalReverb = NULL;
}

// destroy engine object, and invalidate all associated interfaces
if (engineObject != NULL) {
(*engineObject)->Destroy(engineObject);
engineObject = NULL;
engineEngine = NULL;
}

pthread_mutex_destroy(&audioEngineLock);

}

在c中读取assets中的文件，还需引入两个头文件，这两个头文件需要链接android这个库

cmakelists文件：
target_link_libraries( # Specifies the target library.
native-lib
OpenSLES
android
${log-lib} )
c文件：
#include <android/asset_manager.h>
#include <android/asset_manager_jni.h>

这样就可以进行播放了，后面会进行音频录制、分割等方面的研究。

源码地址：https://github.com/luXiuKun/LxkAudio