audio - Android : How to change Playback Rate of music using OpenSL ES

Question

I am working on a music player in which I need to change tempo (playback speed of music) without changing the pitch.

I'm not able to find any native android class to do so. I tried SoundPool but it doesn't work with large music files and it also doesn't seems to work on many devices. I also tried AudioTrack but again no luck.

Now I am trying android NDK audio example which use OpenSL ES to handle music. Now I just want to add set playback rate feature in this example.

Can anyone show me how do I add change playback rate function in it?

Answer 1

I have solved my problem. Here is my complete native code for OpenSL ES in case of anybody need this :

#include <jni.h>

#include<android/log.h>
// LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog ?????
#define LOGV(...) __android_log_print(ANDROID_LOG_VERBOSE, "OSLESMediaPlayer", __VA_ARGS__) 
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG  , "OSLESMediaPlayer", __VA_ARGS__) 
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO   , "OSLESMediaPlayer", __VA_ARGS__) 
#define LOGW(...) __android_log_print(ANDROID_LOG_WARN   , "OSLESMediaPlayer", __VA_ARGS__) 
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR  , "OSLESMediaPlayer", __VA_ARGS__) 

// for native audio
#include <SLES/OpenSLES.h>
#include <SLES/OpenSLES_Android.h>

#include <assert.h>
#include <sys/types.h>

// engine interfaces
static SLObjectItf engineObject = NULL;
static SLEngineItf engineEngine;

// URI player interfaces
static SLObjectItf uriPlayerObject = NULL;
static SLPlayItf uriPlayerPlay;
static SLSeekItf uriPlayerSeek;
static SLPlaybackRateItf uriPlaybackRate;

// output mix interfaces
static SLObjectItf outputMixObject = NULL;

// playback rate (default 1x:1000)
static SLpermille playbackMinRate = 500;
static SLpermille playbackMaxRate = 2000;
static SLpermille playbackRateStepSize;

//Pitch
static SLPitchItf uriPlaybackPitch;
static SLpermille playbackMinPitch = 500;
static SLpermille playbackMaxPitch = 2000;

// create the engine and output mix objects
JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_createEngine(
        JNIEnv* env, jclass clazz) {
    SLresult result;

    // create engine
    LOGD("create engine");
    result = slCreateEngine(&engineObject, 0, NULL, 0, NULL, NULL);
    assert(SL_RESULT_SUCCESS == result);

    // realize the engine
    LOGD("realize the engine");
    result = (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);
    assert(SL_RESULT_SUCCESS == result);

    // get the engine interface, which is needed in order to create other objects
    LOGD("get the engine interface");
    result = (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE,
            &engineEngine);
    assert(SL_RESULT_SUCCESS == result);

    // create output mix, with environmental reverb specified as a non-required interface
    LOGD("create output mix");
    const SLInterfaceID ids[1] = {SL_IID_PLAYBACKRATE};
    const SLboolean req[1] = {SL_BOOLEAN_FALSE};
    result = (*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject, 1,
            ids, req);
    assert(SL_RESULT_SUCCESS == result);

    // realize the output mix
    LOGD("realize the output mix");
    result = (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);
    assert(SL_RESULT_SUCCESS == result);

}

JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_releaseEngine(
        JNIEnv* env, jclass clazz) {
    // destroy URI audio player object, and invalidate all associated interfaces
    if (uriPlayerObject != NULL) {
        (*uriPlayerObject)->Destroy(uriPlayerObject);
        uriPlayerObject = NULL;
        uriPlayerPlay = NULL;
        uriPlayerSeek = NULL;
    }

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

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

}

/*
 void OnCompletion(JNIEnv* env, jclass clazz)
 {
 jclass cls = env->GetObjectClass(thiz);
 if (cls != NULL)
 {
 jmethodID mid = env->GetMethodID(cls, "OnCompletion", "()V");
 if (mid != NULL)
 {
 env->CallVoidMethod(thiz, mid, 1234);
 }
 }
 }*/

void playStatusCallback(SLPlayItf play, void* context, SLuint32 event) {
    //LOGD("playStatusCallback");
}

// create URI audio player
JNIEXPORT jboolean Java_com_swssm_waveloop_audio_OSLESMediaPlayer_createAudioPlayer(
        JNIEnv* env, jclass clazz, jstring uri) {
    SLresult result;

    // convert Java string to UTF-8
    const jbyte *utf8 = (*env)->GetStringUTFChars(env, uri, NULL);
    assert(NULL != utf8);

    // configure audio source
    // (requires the INTERNET permission depending on the uri parameter)
    SLDataLocator_URI loc_uri = { SL_DATALOCATOR_URI, (SLchar *) utf8 };
    SLDataFormat_MIME format_mime = { SL_DATAFORMAT_MIME, NULL,
            SL_CONTAINERTYPE_UNSPECIFIED };
    SLDataSource audioSrc = { &loc_uri, &format_mime };

    // configure audio sink
    SLDataLocator_OutputMix loc_outmix = { SL_DATALOCATOR_OUTPUTMIX,
            outputMixObject };
    SLDataSink audioSnk = { &loc_outmix, NULL };

    // create audio player
    const SLInterfaceID ids[2] = { SL_IID_SEEK, SL_IID_PLAYBACKRATE };
    const SLboolean req[2] = { SL_BOOLEAN_FALSE, SL_BOOLEAN_TRUE };
    result = (*engineEngine)->CreateAudioPlayer(engineEngine, &uriPlayerObject,
            &audioSrc, &audioSnk, 2, ids, req);
    // note that an invalid URI is not detected here, but during prepare/prefetch on Android,
    // or possibly during Realize on other platforms
    assert(SL_RESULT_SUCCESS == result);

    // release the Java string and UTF-8
    (*env)->ReleaseStringUTFChars(env, uri, utf8);

    // realize the player
    result = (*uriPlayerObject)->Realize(uriPlayerObject, SL_BOOLEAN_FALSE);
    // this will always succeed on Android, but we check result for portability to other platforms
    if (SL_RESULT_SUCCESS != result) {
        (*uriPlayerObject)->Destroy(uriPlayerObject);
        uriPlayerObject = NULL;
        return JNI_FALSE;
    }

    // get the play interface
    result = (*uriPlayerObject)->GetInterface(uriPlayerObject, SL_IID_PLAY,
            &uriPlayerPlay);
    assert(SL_RESULT_SUCCESS == result);

    // get the seek interface
    result = (*uriPlayerObject)->GetInterface(uriPlayerObject, SL_IID_SEEK,
            &uriPlayerSeek);
    assert(SL_RESULT_SUCCESS == result);

    // get playback rate interface
    result = (*uriPlayerObject)->GetInterface(uriPlayerObject,
            SL_IID_PLAYBACKRATE, &uriPlaybackRate);
    assert(SL_RESULT_SUCCESS == result);

    /*  // get playback pitch interface
     result = (*uriPlayerObject)->GetInterface(uriPlayerObject, SL_IID_PITCH, &uriPlaybackPitch);
     assert(SL_RESULT_SUCCESS == result);*/

    // register callback function
    result = (*uriPlayerPlay)->RegisterCallback(uriPlayerPlay,
            playStatusCallback, 0);
    assert(SL_RESULT_SUCCESS == result);
    result = (*uriPlayerPlay)->SetCallbackEventsMask(uriPlayerPlay,
            SL_PLAYEVENT_HEADATEND); // head at end
    assert(SL_RESULT_SUCCESS == result);

    SLmillisecond msec;
    result = (*uriPlayerPlay)->GetDuration(uriPlayerPlay, &msec);
    assert(SL_RESULT_SUCCESS == result);

    // no loop
    result = (*uriPlayerSeek)->SetLoop(uriPlayerSeek, SL_BOOLEAN_TRUE, 0, msec);
    assert(SL_RESULT_SUCCESS == result);


    SLuint32 capa;
        result = (*uriPlaybackRate)->GetRateRange(uriPlaybackRate, 0,
                &playbackMinRate, &playbackMaxRate, &playbackRateStepSize, &capa);
        assert(SL_RESULT_SUCCESS == result);

        result = (*uriPlaybackRate)->SetPropertyConstraints(uriPlaybackRate,
                        SL_RATEPROP_PITCHCORAUDIO);

                    if (SL_RESULT_PARAMETER_INVALID == result) {
                        LOGD("Parameter Invalid");
                    }
                    if (SL_RESULT_FEATURE_UNSUPPORTED == result) {
                            LOGD("Feature Unsupported");
                        }
                    if (SL_RESULT_SUCCESS == result) {
                        assert(SL_RESULT_SUCCESS == result);
                            LOGD("Success");
                        }
    /*
     result = (*uriPlaybackPitch)->GetPitchCapabilities(uriPlaybackPitch, &playbackMinPitch, &playbackMaxPitch);
     assert(SL_RESULT_SUCCESS == result);*/

    /*
     SLpermille minRate, maxRate, stepSize, rate = 1000;
     SLuint32 capa;
     (*uriPlaybackRate)->GetRateRange(uriPlaybackRate, 0, &minRate, &maxRate, &stepSize, &capa);

     (*uriPlaybackRate)->SetRate(uriPlaybackRate, minRate);
     */
    return JNI_TRUE;
}

JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_releaseAudioPlayer(
        JNIEnv* env, jclass clazz) {
    // destroy URI audio player object, and invalidate all associated interfaces
    if (uriPlayerObject != NULL) {
        (*uriPlayerObject)->Destroy(uriPlayerObject);
        uriPlayerObject = NULL;
        uriPlayerPlay = NULL;
        uriPlayerSeek = NULL;
        uriPlaybackRate = NULL;
    }

}

void setPlayState(SLuint32 state) {
    SLresult result;

    // make sure the URI audio player was created
    if (NULL != uriPlayerPlay) {

        // set the player's state
        result = (*uriPlayerPlay)->SetPlayState(uriPlayerPlay, state);
        assert(SL_RESULT_SUCCESS == result);
    }

}

SLuint32 getPlayState() {
    SLresult result;

    // make sure the URI audio player was created
    if (NULL != uriPlayerPlay) {

        SLuint32 state;
        result = (*uriPlayerPlay)->GetPlayState(uriPlayerPlay, &state);
        assert(SL_RESULT_SUCCESS == result);

        return state;
    }

    return 0;

}

// play
JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_play(JNIEnv* env,
        jclass clazz) {
    setPlayState(SL_PLAYSTATE_PLAYING);
}

// stop
JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_stop(JNIEnv* env,
        jclass clazz) {
    setPlayState(SL_PLAYSTATE_STOPPED);
}

// pause
JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_pause(JNIEnv* env,
        jclass clazz) {
    setPlayState(SL_PLAYSTATE_PAUSED);
}

// pause
JNIEXPORT jboolean Java_com_swssm_waveloop_audio_OSLESMediaPlayer_isPlaying(
        JNIEnv* env, jclass clazz) {
    return (getPlayState() == SL_PLAYSTATE_PLAYING);
}

// set position
JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_seekTo(
        JNIEnv* env, jclass clazz, jint position) {
    if (NULL != uriPlayerPlay) {

        //SLuint32 state = getPlayState();
        //setPlayState(SL_PLAYSTATE_PAUSED);

        SLresult result;

        result = (*uriPlayerSeek)->SetPosition(uriPlayerSeek, position,
                SL_SEEKMODE_FAST);
        assert(SL_RESULT_SUCCESS == result);

        //setPlayState(state);
    }

}

// get duration
JNIEXPORT jint Java_com_swssm_waveloop_audio_OSLESMediaPlayer_getDuration(
        JNIEnv* env, jclass clazz) {
    if (NULL != uriPlayerPlay) {

        SLresult result;

        SLmillisecond msec;
        result = (*uriPlayerPlay)->GetDuration(uriPlayerPlay, &msec);
        assert(SL_RESULT_SUCCESS == result);

        return msec;
    }

    return 0.0f;
}

// get current position
JNIEXPORT jint Java_com_swssm_waveloop_audio_OSLESMediaPlayer_getPosition(
        JNIEnv* env, jclass clazz) {
    if (NULL != uriPlayerPlay) {

        SLresult result;

        SLmillisecond msec;
        result = (*uriPlayerPlay)->GetPosition(uriPlayerPlay, &msec);
        assert(SL_RESULT_SUCCESS == result);

        return msec;
    }

    return 0.0f;
}

//llllllllllllllllllll

JNIEXPORT void Java_com_swssm_waveloop_audio_OSLESMediaPlayer_setPitch(
        JNIEnv* env, jclass clazz, jint rate) {
    if (NULL !