cocos2dx 音频模块分析(4): 音效部分
我们上面几篇分析了cocos2dx音频模块的音乐部分，从这篇开始， 我们分析下音效部分： 1、 //预加载音效文件：pszFilePath 音效文件名 void SimpleAudioEngine::preloadEffect(const char* pszFilePath) { //获取音效文件的全路径，如果是apk包里的路径，则不包含assets/ std::string fullPath = getFullPathWithoutAssetsPrefix(pszFilePath); preloadEffectJNI(fullPath.c_str()); } --->>>// 这里通过jni调用java端的方法 void preloadEffectJNI(const char *path) { // void preloadEffect(String) JniMethodInfo methodInfo; if (! getStaticMethodInfo(methodInfo,"preloadEffect","(Ljava/lang/String;)V")) { return ; } jstring stringArg = methodInfo.env->NewStringUTF(path); methodInfo.env->CallStaticVoidMethod(methodInfo.classID,methodInfo.methodID,stringArg); methodInfo.env->DeleteLocalRef(stringArg); methodInfo.env->DeleteLocalRef(methodInfo.classID); } ----->>>//Cocos2dxHelper类中的方法： public static void preloadEffect(final String path) { //Cocos2dxSound类是专门处理音效的类 Cocos2dxHelper.sCocos2dSound.preloadEffect(path); } --->>>//Cocos2dxSound类的方法： public int preloadEffect(final String pPath) { //private final HashMap<String,Integer> mPathSoundIDMap = new HashMap<String,Integer>(); //这个是音效路径对应音效ID的map Integer soundID = this.mPathSoundIDMap.get(pPath); if (soundID == null) { // soundID = this.createSoundIDFromAsset(pPath); // save value just in case if file is really loaded // 如果createSoundIDFromAsset函数调用成功，则添加到mPathSoundIDMap中。 if (soundID != Cocos2dxSound.INVALID_SOUND_ID) { this.mPathSoundIDMap.put(pPath,soundID); } } return soundID; } ----->>>>根据我们传入的音效文件路径，加载音效 public int createSoundIDFromAsset(final String pPath) { int soundID = Cocos2dxSound.INVALID_SOUND_ID; try { //根据传入的路径不同，做不同处理，一个是绝对路径一个是包里的路径，加载音效文件 //The SoundPool class manages and plays audio resources for applications. //private SoundPool mSoundPool;音效缓存池 if (pPath.startsWith("/")) { soundID = this.mSoundPool.load(pPath,0); } else { soundID = this.mSoundPool.load(this.mContext.getAssets().openFd(pPath),0); } } catch (final Exception e) { soundID = Cocos2dxSound.INVALID_SOUND_ID; Log.e(Cocos2dxSound.TAG,"error: " + e.getMessage(),e); } // mSoundPool.load returns 0 if something goes wrong,for example a file does not exist if (soundID == 0) { soundID = Cocos2dxSound.INVALID_SOUND_ID; } return soundID; } 2、 播放音效文件。 pszFilePath：音效文件名；bLoop 是否循环播放 unsigned int SimpleAudioEngine::playEffect(const char* pszFilePath,bool bLoop) { std::string fullPath = getFullPathWithoutAssetsPrefix(pszFilePath); return playEffectJNI(fullPath.c_str(),bLoop); } ----->>>playEffectJNI： unsigned int playEffectJNI(const char* path,bool bLoop) { // int playEffect(String) JniMethodInfo methodInfo; int ret = 0; if (! getStaticMethodInfo(methodInfo,"playEffect","(Ljava/lang/String;Z)I")) { return ret; } jstring stringArg = methodInfo.env->NewStringUTF(path); ret = methodInfo.env->CallStaticIntMethod(methodInfo.classID,stringArg,bLoop); methodInfo.env->DeleteLocalRef(stringArg); methodInfo.env->DeleteLocalRef(methodInfo.classID); return (unsigned int)ret; } ------>>>>playEffect： public int playEffect(final String pPath,final boolean pLoop) { //从mPathSoundIDMap中，根据音效path得到音效ID Integer soundID = this.mPathSoundIDMap.get(pPath); int streamID = Cocos2dxSound.INVALID_STREAM_ID; if (soundID != null) { // play sound // 如果音效ID存在，则表明我们已经预先加载过这个音效文件，则调用mSoundPool.play直接播放 /* private int doPlayEffect(final String pPath,final int soundId,final boolean pLoop) { // play sound // Play a sound from a sound ID. // return non-zero streamID if successful,zero if Failed如果成功会返回一个streamID int streamID = this.mSoundPool.play(soundId,this.mLeftVolume,this.mRightVolume,Cocos2dxSound.SOUND_PRIORITY,pLoop ? -1 : 0,Cocos2dxSound.SOUND_RATE); // record stream id // 记录上面调用mSoundPool.play返回的streamID，至于为什么需要这样，看下面源码的说明： // sound path and stream ids map // a file may be played many times at the same time // so there is an array map to a file path // private final HashMap<String,ArrayList<Integer>> mPathStreamIDsMap = new HashMap<String,ArrayList<Integer>>(); ArrayList<Integer> streamIDs = this.mPathStreamIDsMap.get(pPath); if (streamIDs == null) { streamIDs = new ArrayList<Integer>(); this.mPathStreamIDsMap.put(pPath,streamIDs); } streamIDs.add(streamID); return streamID; } */ streamID = this.doPlayEffect(pPath,soundID.intValue(),pLoop); } else { // the effect is not prepared，如果音效没有预先加载，则需要先加载 soundID = this.preloadEffect(pPath); //加载音效文件 if (soundID == Cocos2dxSound.INVALID_SOUND_ID) { // can not preload effect return Cocos2dxSound.INVALID_SOUND_ID; } // only allow one playEffect at a time,or the semaphore will not work correctly synchronized(this.mSoundPool) { // add this effect into mEffecToPlayWhenLoadedArray,and it will be played when loaded completely // 这个应该和mSoundPool加载音效文件有关，我也不是很明白 /* 不过在初始化时设置了一个：this.mSoundPool.setOnLoadCompleteListener(new OnLoadCompletedListener()); //加载完成回调函数，应该和这个有关，这里我们就不关心了。 只需要知道如果我们提前加载音效文件 //也可以直接调用play函数，在调用play函数时会调用加载函数，并放入加载队列中，加载完成后进行播放。 //这样做会有一些延时，所以我们还是最好先加载，然后在播放。这个延时只在第一次播放时有，以后就不会了， //不过最好还是先加载。 */ /* @Override //加载完成回调函数。 public void onLoadComplete(SoundPool soundPool,int sampleId,int status) { if (status == 0) { // only play effect that are in mEffecToPlayWhenLoadedArray for ( SoundInfoForLoadedCompleted info : mEffecToPlayWhenLoadedArray) { if (sampleId == info.soundID) { // set the stream id which will be returned by playEffect() // 加载完成后调用doPlayEffect进行播放，并从mEffecToPlayWhenLoadedArray加载列表中 // 移除。 mStreamIdSyn = doPlayEffect(info.path,info.soundID,info.isLoop); // remove it from array,because we will break here // so it is safe to do mEffecToPlayWhenLoadedArray.remove(info); break; } } } else { mStreamIdSyn = Cocos2dxSound.INVALID_SOUND_ID; } mSemaphore.release(); } } */ mEffecToPlayWhenLoadedArray.add(new SoundInfoForLoadedCompleted(pPath,pLoop)); try { // wait OnloadedCompleteListener to set streamID this.mSemaphore.acquire(); streamID = this.mStreamIdSyn; } catch(Exception e) { return Cocos2dxSound.INVALID_SOUND_ID; } } } return streamID; }原文链接：https://www.f2er.com/cocos2dx/342931.html
