Android Audio and Video learning 7th: decoding with OpenSL es

/*
*
* The WAV file is decoded using transcode-1.1.7 and then played using OpenSL ES
*
*/

Variables and structures used

WAV wav;//wav file PointerSLOBJECTITF Engineobject;//Engine ObjectSLENGINEITF Engineinterface;//Engine interfaceSLOBJECTITF Outputmixobject;//MixerSLOBJECTITF Audioplayerobject;//Player ObjectSLANDROIDSIMPLEBUFFERQUEUEITF ANDIOPLAYERBUFFERQUEUEITF;//Buffer Queue InterfaceSLPLAYITF Audioplayinterface;//Play InterfaceUnsignedChar*buffer;//Buffersize_t buffersize;//Buffer size//Contextstructplayercontext{wav wav; UnsignedChar*buffer;    size_t buffersize; Playercontext (WAV wav, unsignedChar*buffer, size_t buffersize) { This->wav = wav; This->buffer = buffer; This->buffersize = buffersize; }};//Implementation ObjectvoidRealizeobject (SLOBJECTITFObject){//non-asynchronous (blocking)(*Object)->realize (Object, sl_boolean_false);}

Specific implementation process: 1. Open file

WAV wav = OpenWaveFile(env,jFileName);

*env,jstring jFileName){    *cFileName = env->GetStringUTFChars(jFileName,JNI_FALSE);    WAVError err;    WAV wav = wav_open(cFileName,WAV_READ,&err);    LOGI("%d",wav_get_bitrate(wav));    env->ReleaseStringUTFChars(jFileName,cFileName);    if0){        LOGE("%s",wav_strerror(err));    }    return wav;}

2. Create the OpenSL es engine

//OpenSL ES在Android平台下默认是线程安全的，这样设置是为了为了兼容其他平台    SLEngineOption options[] = {        {(SLuint32)SL_ENGINEOPTION_THREADSAFE, (SLuint32)SL_BOOLEAN_TRUE}    };    slCreateEngine(&engineObject,ARRAY_LEN(engineObject),options,0,0,0//没有接口//实例化对象    //对象创建之后，处于未实例化状态，对象虽然存在但未分配任何资源，使用前先实例化（使用完之后destroy）    RealizeObject(engineObject);

3. Get the Engine interface

(*engineObject)->GetInterface(engineObject,SL_IID_ENGINE,&engineInterface);

4. Create an output mixer

(*engineInterface)->CreateOutputMix(engineInterface,&outputMixObject,0,0,0)//没有接口    //实例化混音器    RealizeObject(outputMixObject);

5. Create a buffer to save the read to the audio database

//缓冲区的大小    bufferSize = wav_get_channels(wav) * wav_get_rate(wav) * wav_get_bits(wav);    newunsignedchar[bufferSize];

6. Create an audio player with a buffer queue

CreateBufferQueueAudioPlayer(wav,engineInterface,outputMixObject,audioPlayerObject);    //实例化音频播放器    RealizeObject(audioPlayerObject);

CreateBufferQueueAudioPlayer.cpp

extern"C"{#include "wavlib.h"}#include <SLES/OpenSLES.h>#include <SLES/OpenSLES_Android.h>#include <android/log.h>#define Array_len (a) (sizeof (a)/sizeof (a[0))//Create an audio playback objectvoidCreatebufferqueueaudioplayer (WAVWAV, SLENGINEITF engineengine, SLOBJECTITF outputmixobject, SLOBJECTITF &audioplayerobject) {//Android Simple buffer queue locator for data sourcesSldatalocator_androidsimplebufferqueue Datasourcelocator = {Sl_datalocator_androidsimplebufferqueue,//Locator type        1                                        //Number of buffers};//PCM data source formatSLDATAFORMAT_PCM Datasourceformat = {SL_DATAFORMAT_PCM,//format typeWav_get_channels (WAV),//Number of channelsWav_get_rate (WAV) * +,number of samples per//Hz/secWav_get_bits (WAV),//Number of bits per sampleWav_get_bits (WAV),//Container sizeSl_speaker_front_center,//Channel Shield       Sl_byteorder_littleendian//byte order};//Data source is a simple buffer queue that contains the PCM formatSldatasource DataSource = {&datasourcelocator,//Data Locator&datasourceformat//Data format};//output hybrid locator for data receiversSldatalocator_outputmix Datasinklocator = {Sl_datalocator_outputmix,//Locator typeOutputmixobject//Output Mix};//Data locator is an output mixSldatasink Datasink = {&datasinklocator,//Locator        0                 //Format};//Required InterfaceSlinterfaceid interfaceids[] = {Sl_iid_bufferqueue};//Required interface, if the required interface is not used, the request will failSlboolean requiredinterfaces[] = {sl_boolean_true//For Sl_iid_bufferqueue};//Create an audio player objectSlresult result = (*engineengine)->createaudioplayer (Engineengine, &audioplayerobject, &datasource, &datasink, Array_len (interfaceids), Interfaceids, R equiredinterfaces);}

7. Get the buffer queue interface buffer Interface

//通过缓冲区队列接口对缓冲区进行排序播放    (*audioPlayerObject)->GetInterface(audioPlayerObject,SL_IID_BUFFERQUEUE,&andioPlayerBufferQueueItf);

8. Register the audio player callback function

//当播放器完成对前一个缓冲区队列的播放时，回调函数会被调用，然后我们又继续读取音频数据，直到结束    //上下文，包裹参数方便再回调函数中使用    new PlayerContext(wav,buffer,bufferSize);    (*andioPlayerBufferQueueItf)->RegisterCallback(andioPlayerBufferQueueItf,PlayerCallBack,ctx);

//callback functionvoidPlayercallback (SLANDROIDSIMPLEBUFFERQUEUEITF Andioplayerbufferqueue,void *Context) {Playercontext*CTx=(Playercontext*) context;//Read Datassize_t readsize=Wav_read_data (CTX -Wav,ctx -Buffer,ctx -buffersize);if(0 <ReadSize) {(*Andioplayerbufferqueue) -Enqueue (Andioplayerbufferqueue,ctx -Buffer,readsize); }Else{//destroy ContextClosewavefile (CTX -WAV);//Close fileDelete CTX -Buffer//Release cache}}

9. Get play interface to start playing music by using the Setplaystate function

//一旦播放器被设置为播放状态，该音频播放器开始等待缓冲区排队就绪    (*audioPlayerObject)->GetInterface(audioPlayerObject,SL_IID_PLAY,&audioPlayInterface);    //设置播放状态    (*audioPlayInterface)->SetPlayState(audioPlayInterface,SL_PLAYSTATE_PLAYING);

10. Start by making the first buffer queue

PlayerCallBack(andioPlayerBufferQueueItf,ctx);

Full code

#include "com_dongnaoedu_jasonaudioplayer_audioplayer.h"extern "C"{#include "wavlib.h"}#include <SLES/OpenSLES.h>#include <SLES/OpenSLES_Android.h>#include <android/log.h>#include "CreateBufferQueueAudioPlayer.cpp"#define Logi (FORMAT,...) __android_log_print (Android_log_info, "Jason", format,# #__VA_ARGS__);#define LOGE (FORMAT,...) __android_log_print (Android_log_error, "Jason", format,# #__VA_ARGS__);#define Array_len (a) (sizeof (a)/sizeof (a[0))WAV wav;//wav file PointerSLOBJECTITF Engineobject;//Engine ObjectSLENGINEITF Engineinterface;//Engine interfaceSLOBJECTITF Outputmixobject;//MixerSLOBJECTITF Audioplayerobject;//Player ObjectSLANDROIDSIMPLEBUFFERQUEUEITF ANDIOPLAYERBUFFERQUEUEITF;//Buffer Queue InterfaceSLPLAYITF Audioplayinterface;//Play Interfaceunsigned Char*buffer;//Buffersize_t buffersize;//Buffer size//Contextstructplayercontext{wav wav;unsigned Char*buffer;    size_t buffersize; Playercontext (WAV wav,unsigned Char*buffer, size_t buffersize) { This->wav = wav; This->buffer = buffer; This->buffersize = buffersize; }};//Open FileWAV openwavefile (jnienv *env,jstring jfilename) {Const Char*cfilename = Env->getstringutfchars (Jfilename,jni_false);    Waverror err;    WAV wav = Wav_open (CFILENAME,WAV_READ,&AMP;ERR); Logi ("%d", Wav_get_bitrate (WAV)); Env->releasestringutfchars (Jfilename,cfilename);if(wav = =0) {LOGE ('%s ', Wav_strerror (err)); }returnWAV;}//Close filevoidClosewavefile (WAV wav) {wav_close (WAV);}//Implementation ObjectvoidRealizeobject (Slobjectitf object) {//non-asynchronous (blocking)(*object)->realize (object,sl_boolean_false);}//callback functionvoidPlayercallback (SLANDROIDSIMPLEBUFFERQUEUEITF Andioplayerbufferqueue,void*context) {playercontext* CTX = (playercontext*) context;//Read Datassize_t readsize = Wav_read_data (ctx->wav,ctx->buffer,ctx->buffersize);if(0< ReadSize) {(*andioplayerbufferqueue)->enqueue (andioplayerbufferqueue,ctx->buffer,readsize); }Else{//destroy ContextClosewavefile (ctx->wav);//Close file        Deletectx->buffer;//Release cache}}jniexportvoidJnicall Java_com_dongnaoedu_jasonaudioplayer_audioplayer_play (jnienv *env, Jclass jthiz, jstring jFileName) {//1. Opening a fileWAV wav = openwavefile (env,jfilename);//2. Creating the OpenSL es engine    //opensl es is thread-safe by default on Android, so it is set up to be compatible with other platformsSlengineoption options[] = {{(SLuint32) Sl_engineoption_threadsafe, (SLuint32) sl_boolean_true}}; Slcreateengine (&engineobject,array_len (engineobject), Options,0,0,0);//No interface    //instanced objects    after the object is created, it is in an destroy state, the object exists but no resources are assigned, and is instantiated before use (after use)Realizeobject (Engineobject);//3. Getting the engine interface(*engineobject)->getinterface (engineobject,sl_iid_engine,&engineinterface);//4. Creating an output mixer(*engineinterface)->createoutputmix (Engineinterface,&outputmixobject,0,0,0);//No interface    //instancing mixerRealizeobject (Outputmixobject);//5. Creating a buffer to save the read to the audio database    //size of bufferbuffersize = wav_get_channels (WAV) * WAV_GET_RATE (WAV) * wav_get_bits (WAV); Buffer =New unsigned Char[BufferSize];//6. Creating an audio player with a buffer queueCreatebufferqueueaudioplayer (Wav,engineinterface,outputmixobject,audioplayerobject);//Instantiate an audio playerRealizeobject (Audioplayerobject);//7. Getting the buffer queue interface buffer queues Interface    //Sort buffers by Buffer queue interface to play(*audioplayerobject)->getinterface (AUDIOPLAYEROBJECT,SL_IID_BUFFERQUEUE,&AMP;ANDIOPLAYERBUFFERQUEUEITF);//8. Registering the audio player callback function    //When the player finishes playing against the previous buffer queue, the callback function is called, and then we continue to read the audio data until the end    //context, wrap parameters easy to use in callback functionPlayercontext *ctx =NewPlayercontext (wav,buffer,buffersize); (*ANDIOPLAYERBUFFERQUEUEITF)->registercallback (ANDIOPLAYERBUFFERQUEUEITF,PLAYERCALLBACK,CTX);//9. Get play interface to start playing music by setplaystate function    //Once the player is set to play, the audio player begins to wait for the buffer to queue ready(*audioplayerobject)->getinterface (audioplayerobject,sl_iid_play,&audioplayinterface);//Set playback status(*audioplayinterface)->setplaystate (audioplayinterface,sl_playstate_playing);//10. Start by getting the first buffer enqueuedPlayercallback (ANDIOPLAYERBUFFERQUEUEITF,CTX);//Close file    //closewavefile (WAV);}

Android Audio and Video learning 7th: decoding with OpenSL es