OpenSL ES音频播放开发指导

 

场景介绍

开发者可以通过本文了解到在OpenHarmony如何使用OpenSL ES进行音频播放相关操作；当前仅实现了部分OpenSL ES接口，未实现接口调用后会返回SL_RESULT_FEATURE_UNSUPPORTED

 

开发步骤

以下步骤描述了在OpenHarmony如何使用OpenSL ES开发音频播放功能：

1. 添加头文件
       #include <OpenSLES.h>
       #include <OpenSLES_OpenHarmony.h>
       #include <OpenSLES_Platform.h>
   
2. 使用 slCreateEngine 接口和获取 engine 实例。
       SLObjectItf engineObject = nullptr;
       slCreateEngine(&engineObject, 0, nullptr, 0, nullptr, nullptr);
       (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);
   
3. 获取接口 SL_IID_ENGINE 的 engineEngine 实例
       SLEngineItf engineEngine = nullptr;
       (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineEngine);
   
4. 配置播放器信息，创建 AudioPlayer 。
       SLDataLocator_BufferQueue slBufferQueue = {
           SL_DATALOCATOR_BUFFERQUEUE,
           0
       };
       
       //具体参数需要根据音频文件格式进行适配
       SLDataFormat_PCM pcmFormat = {
           SL_DATAFORMAT_PCM,
           2,
           48000,
           16,
           0,
           0,
           0
       };
       SLDataSource slSource = {&slBufferQueue, &pcmFormat};
       
       SLObjectItf pcmPlayerObject = nullptr;
       (*engineEngine)->CreateAudioPlayer(engineEngine, &pcmPlayerObject, &slSource, null, 0, nullptr, nullptr);
       (*pcmPlayerObject)->Realize(pcmPlayerObject, SL_BOOLEAN_FALSE);
   
5. 获取接口 SL_IID_OH_BUFFERQUEUE 的 bufferQueueItf 实例
       SLOHBufferQueueItf bufferQueueItf;
       (*pcmPlayerObject)->GetInterface(pcmPlayerObject, SL_IID_OH_BUFFERQUEUE, &bufferQueueItf);
   
6. 打开音频文件，注册 BuqqerQueueCallback 回调
       FILE *wavFile_ = nullptr;
       
       static void BuqqerQueueCallback (SLOHBufferQueueItf bufferQueueItf, void *pContext, SLuint32 size)
       {
           FILE *wavFile = (FILE *)pContext;
           if (!feof(wavFile)) {
               SLuint8 *buffer = nullptr;
               SLuint32 pSize = 0;
               (*bufferQueueItf)->GetBuffer(bufferQueueItf, &buffer, pSize);
               //从文件读取数据
               fread(buffer, 1, size, wavFile);
               (*bufferQueueItf)->Enqueue(bufferQueueItf, buffer, size);
           }
           return;
       }
       
       //wavFile_ 需要设置为用户想要播放的文件描述符
       wavFile_ = fopen(path, "rb");
       (*bufferQueueItf)->RegisterCallback(bufferQueueItf, BuqqerQueueCallback, wavFile_);
   
7. 获取接口 SL_PLAYSTATE_PLAYING 的 playItf 实例，开始播放
       SLPlayItf playItf = nullptr;
       (*pcmPlayerObject)->GetInterface(pcmPlayerObject, SL_IID_PLAY, &playItf);
       (*playItf)->SetPlayState(playItf, SL_PLAYSTATE_PLAYING);
   
8. 结束音频播放
       (*playItf)->SetPlayState(playItf, SL_PLAYSTATE_STOPPED);
       (*pcmPlayerObject)->Destroy(pcmPlayerObject);
       (*engineObject)->Destroy(engineObject);