How to use Opensl ES (aka low level audio) on Android - Part of a Spotify mobile App I wrote

opensles_android.cpp

/*  Code Written by mox1
 *  http://moxone.me/
 *  The code contained within is part of a larger Android Application. Portions of this code
 *  also rely on the "Poco" C++ library. 
 *
 *  Copyright (c) 2015, [email protected]
 *  All rights reserved.
 * 
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 * 
 *  1. Redistributions of source code must retain the above copyright notice, this
 *     list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation      
 *   and/or other materials provided with the distribution.
 *  
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 *  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 *  ( (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *  The views and conclusions contained in the software and documentation are those
 *  of the authors and should not be interpreted as representing official policies,
 *  either expressed or implied, of the author's affiliated organizations.
*/

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


bool SpotLib::init_audio() {
	engineObject = NULL;
	outputMixObject = NULL;
	bqPlayerObject = NULL;
	bqPlayerBufferQueue = NULL;
	bqPlayerPlay = NULL;
	Poco::Int16 x;

	SLresult result;

	// create engine

	result = slCreateEngine(&engineObject, 0, NULL, 0, NULL, NULL);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}

	// realize the engine
	result = (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE );
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}

	// get the engine interface, which is needed in order to create other objects
	result = (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineEngine);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}

	/*If we ever encounter a Spotify song with > 2 channels, this is going to be a problem here */

	for(x=0; x<NUM_ANDROID_BUFFERS; x++) {
		audio_data[x] = (Poco::Int16 *) calloc(1,(MAX_SL_AUDIO_FRAMES * sizeof(Poco::Int16) * 2));
		if (audio_data[x] == NULL) {
			SSDEBUG("calloc() error!");
		return false;
		}
	}
	cur_audio_buf = 0;
	need_audio_start = true;
	SSINFO("Android audio initialized successfully");

	return true;

}


bool SpotLib::open_audio_stream(const int sample_format,const int sample_rate,const int channels) {
	SLresult result;
	SLuint32 sf;
	SLuint32 sr;
	int speakers;


	if (audiobuffer == NULL) {
		//allocate a 1mb audio buffer
		audiobuffer = new AudioBuffer2((1024*1024*1),sample_rate,channels);
		//allocate a 64k audio buffer
		//audiobuffer = new AudioBuffer2((64*1024*1),sample_rate,channels);
		SSDEBUG("Allocated audiobuffer2!");
	}
	else {
		audiobuffer->reset(sample_rate,channels);
	}


	switch (channels) {
		case (1):
			speakers = SL_SPEAKER_FRONT_CENTER;
			break;
		default:
			speakers = SL_SPEAKER_FRONT_LEFT | SL_SPEAKER_FRONT_RIGHT;
			break;
	}

	switch(sample_format) {
		case SP_SAMPLETYPE_INT16_NATIVE_ENDIAN:
			sf = SL_PCMSAMPLEFORMAT_FIXED_16;
			break;
		default:
			SSERROR("UNKNOWN SPOTIFY SAMPLE RATE!!! %?d", sample_format);
			return false;
	}
	switch(sample_rate) {
		case 44100:
			sr = SL_SAMPLINGRATE_44_1;
			break;
		default:
			SSWARN("Unknown Spotify sample format, %?u setting for 44.1",sample_format);
			sr = SL_SAMPLINGRATE_44_1;
			break;
	}



	const SLInterfaceID ids[] = { SL_IID_VOLUME };
	const SLboolean req[] = { SL_BOOLEAN_FALSE };
	result = (*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject, 1, ids, req);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}
	result = (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE );
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}

	// The source is the buffer
	SLDataLocator_AndroidSimpleBufferQueue loc_bufq = { SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, NUM_ANDROID_BUFFERS };
	SLDataFormat_PCM format_pcm = { SL_DATAFORMAT_PCM, channels, sr, sf, sf,speakers, SL_BYTEORDER_LITTLEENDIAN };
	SLDataSource audioSrc = { &loc_bufq, &format_pcm };

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

	//create audio player
	const SLInterfaceID ids1[] = {SL_IID_ANDROIDSIMPLEBUFFERQUEUE};
	const SLboolean req1[] = {SL_BOOLEAN_TRUE};
	result = (*engineEngine)->CreateAudioPlayer(engineEngine,&bqPlayerObject, &audioSrc, &audioSnk,1, ids1, req1);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}
	//realize player
	result = (*bqPlayerObject)->Realize(bqPlayerObject,SL_BOOLEAN_FALSE);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}

	//get the play interface
	result = (*bqPlayerObject)->GetInterface(bqPlayerObject,SL_IID_PLAY,&bqPlayerPlay);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}
	//get buffer q interface
	result = (*bqPlayerObject)->GetInterface(bqPlayerObject,SL_IID_ANDROIDSIMPLEBUFFERQUEUE, &bqPlayerBufferQueue);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}
	//register callback on buffer q
	result = (*bqPlayerBufferQueue)->RegisterCallback(bqPlayerBufferQueue,wrapper_bqPlayerCallback, NULL);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}

	SSINFO("Audio stream opened successfully");
	return true;
}


void SpotLib::bqPlayerCallback(SLAndroidSimpleBufferQueueItf bq,void *context) {
	SLresult result;
	Poco::Int32 bytes;

	if (audiobuffer == NULL) {
		SSERROR("In audio callback, with null audiobuffer! WTF!!!");
		return;
	}

	bytes = audiobuffer->readFromBuffer(audio_data[cur_audio_buf],MAX_SL_AUDIO_FRAMES);

	while (bytes <= 0) {
		//This means we don't have enough / any audio to play, sleep
		//for 2 seconds
		SSDEBUG("Not enough audio, waiting");
		audiobuffer->waitOnData(500);
		//lets make sure audio hasn't "Stopped"
		if (audio_status != AS_PLAYING ) {
			SSDEBUG("bqPlayerCallback, audio state changed %?u", audio_status);
			return;
		}
		//nope were good, loop around
		bytes = audiobuffer->readFromBuffer(audio_data[cur_audio_buf],MAX_SL_AUDIO_FRAMES);
	}

	//Now call EnQueue
	//bytes = MAX_SL_AUDIO_FRAMES*sizeof(Poco::Int16)*audiobuffer->cur_channels;
	//SSDEBUG("bqPlayerCallback queueing %?d bytes!",bytes);
	result = (*bqPlayerBufferQueue)->Enqueue(bqPlayerBufferQueue,audio_data[cur_audio_buf],bytes);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
	}
	cur_audio_buf += 1;
	cur_audio_buf = cur_audio_buf % NUM_ANDROID_BUFFERS;


}

bool SpotLib::start_audio() {
	SLresult result;
	if(need_audio_start == false) return false;

	if (bqPlayerPlay == false) {
		SSERROR("Call to start_audio() with NULL bqPlayer!");
		return false;
	}

	need_audio_start = false;
	attempt_start_audio = false;
	SSDEBUG("STarting audio playback, OpenSL");
	events->rem_q_by_t(ET_AUDIO_START);
	//set the players state to playing

	result = (*bqPlayerPlay)->SetPlayState(bqPlayerPlay,SL_PLAYSTATE_PLAYING);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
	}

	bqPlayerCallback(bqPlayerBufferQueue,NULL);
	return true;
}

void SpotLib::stop_audio() {
	SLresult result;
	if (need_audio_start == true) return;
	//set the players state to paused
	result = (*bqPlayerPlay)->SetPlayState(bqPlayerPlay,SL_PLAYSTATE_STOPPED);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
	}
	need_audio_start = true;
}

void SpotLib::pause_audio() {
	SLresult result;
	if (need_audio_start == true) return;
	//set the players state to paused
	result = (*bqPlayerPlay)->SetPlayState(bqPlayerPlay,SL_PLAYSTATE_PAUSED);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
	}
}

bool SpotLib::resume_audio() {
	SLresult result;
	//set the players state to paused
	result = (*bqPlayerPlay)->SetPlayState(bqPlayerPlay,SL_PLAYSTATE_PLAYING);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
		return false;
	}
	return true;

}


void SpotLib::flush_audio_stream() {
	SLresult result;
	result = (*bqPlayerBufferQueue)->Clear(bqPlayerBufferQueue);
	if(result != SL_RESULT_SUCCESS) {
		SSDEBUG("Android audio error: %?u", result);
	}
}

opensles_android.h

/*  Code Written by mox1
 *  http://moxone.me/
 *  The code contained within is part of a larger Android Application. Portions of this code
 *  also rely on the "Poco" C++ library. 
 *
 *  Copyright (c) 2015, [email protected]
 *  All rights reserved.
 * 
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 * 
 *  1. Redistributions of source code must retain the above copyright notice, this
 *     list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation      
 *   and/or other materials provided with the distribution.
 *  
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 *  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 *  ( (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *  The views and conclusions contained in the software and documentation are those
 *  of the authors and should not be interpreted as representing official policies,
 *  either expressed or implied, of the author's affiliated organizations.
*/


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

SLObjectItf engineObject;
SLEngineItf engineEngine;
// output mix interfaces
SLObjectItf outputMixObject;
SLObjectItf bqPlayerObject;
SLPlayItf bqPlayerPlay;
Poco::Int16 *audio_data[3];
Poco::Int8 cur_audio_buf;
//Buffer object
SLAndroidSimpleBufferQueueItf bqPlayerBufferQueue;
#define MAX_SL_AUDIO_FRAMES 8096*4
#define NUM_ANDROID_BUFFERS 2



void SP_CALLCONV wrapper_bqPlayerCallback( SLAndroidSimpleBufferQueueItf bq,void *context);