五、OpenSL ES音频播放

本文基于以下文章进行的开发：

一、FFMPEG源码编译

二、AndroidStudio集成FFMPEG

三、FFMPEG视频解码及播放

四、FFMPEG播放音频

开发出色的音频应用

OpenSL ES API 可以帮助您制定和提升应用的音频性能。 某些典型用例包括以下组成部分：

• 数字音频工作站 (DAW)。
• 合成器。
• 电子鼓。
• 音乐学习应用。
• 卡拉 OK 应用。
• DJ 混合。
• 音频效果。
• 视频/音频会议。

OpenSL ES 入门指南

1.cpp目录下新建FFmpegMusic.h和FFmpegMusic.cpp

FFmpegMusic.h

//// Created by ygdx_lk on 17/11/3.//#ifndef FFMPEG_FFMPEGMUSIC_H#define FFMPEG_FFMPEGMUSIC_H#include <jni.h>#include <string>#include <android/log.h>extern "C" {//编码#include "libavcodec/avcodec.h"//封装格式处理#include "libavformat/avformat.h"#include "libswresample/swresample.h"//像素处理#include "libswscale/swscale.h"#include <android/native_window_jni.h>#include <unistd.h>}#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__);int createFFmpeg(int *rate,int *channel);int getPcm(void **pcm,size_t *pcm_size);void realseFFmpeg();#endif //FFMPEG_FFMPEGMUSIC_H

FFmpegMusic.h

//// Created by ygdx_lk on 17/11/3.//#include "FFmpegMusic.h"AVFormatContext *avFormatContext;AVCodecContext *avCodecContext;AVCodec *aVCodec;AVPacket *packet;AVFrame *frame;SwrContext *swrContext;uint8_t *out_buffer;int out_channer_nb;int audio_stream_idx = -1;int createFFmpeg(int *rate,int *channel){    av_register_all();    char *input = "/sdcard/input.mp3";    avFormatContext = avformat_alloc_context();    //0 on success, a negative AVERROR on failure    if(avformat_open_input(&avFormatContext, input, NULL, NULL) < 0){        LOGE("%s", "打开输入音频失败");        return  -1;    }    //>=0 if OK    if(avformat_find_stream_info(avFormatContext, NULL) < 0){        LOGE("%s", "获取资源信息失败");        return -1;    }    for (int i = 0; i < avFormatContext->nb_streams; ++i) {        if(avFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO){            audio_stream_idx = i;            break;        }    }    avCodecContext = avFormatContext->streams[audio_stream_idx]->codec;    aVCodec = avcodec_find_decoder(avCodecContext->codec_id);    //zero on success, a negative value on error    if(avcodec_open2(avCodecContext, aVCodec, NULL) < 0){        LOGE("%s", "打开解码器失败");        return -1;    }    //设置输入输出转换信息//    struct SwrContext *swr_alloc_set_opts(struct SwrContext *s,//                                          int64_t out_ch_layout, enum AVSampleFormat out_sample_fmt, int out_sample_rate,//                                          int64_t  in_ch_layout, enum AVSampleFormat  in_sample_fmt, int  in_sample_rate,//                                          int log_offset, void *log_ctx);    swrContext = swr_alloc();    int64_t out_ch_layout = AV_CH_LAYOUT_STEREO;//立体声    enum AVSampleFormat out_sample_fmt = AV_SAMPLE_FMT_S16;//输出采样率16位    int out_sample_rate = avCodecContext->sample_rate;    swr_alloc_set_opts(swrContext, out_ch_layout, out_sample_fmt, out_sample_rate,                       avCodecContext->channel_layout, avCodecContext->sample_fmt, avCodecContext->sample_rate,                       0, NULL);    swr_init(swrContext);    //获取声道数    out_channer_nb = av_get_channel_layout_nb_channels(AV_CH_LAYOUT_STEREO);    *rate = avCodecContext->sample_rate;    *channel = avCodecContext->channels;    packet = (AVPacket *) av_malloc(sizeof(AVPacket));    frame = av_frame_alloc();    out_buffer = (uint8_t *) av_malloc(44100 * 2);    return 0;}int getPcm(void **pcm,size_t *pcm_size){    LOGI("%s", "getPcm--");    int got_frame;    //0 if OK, < 0 on error or end of file    while (av_read_frame(avFormatContext, packet) == 0){        LOGI("%s", "getPcm——read_frame")        if(packet->stream_index == audio_stream_idx){//            int avcodec_decode_audio4(AVCodecContext *avctx, AVFrame *frame,//                                      int *got_frame_ptr, const AVPacket *avpkt);            avcodec_decode_audio4(avCodecContext, frame, &got_frame, packet);            if(got_frame){//                int swr_convert(struct SwrContext *s, uint8_t **out, int out_count,//                                const uint8_t **in , int in_count);                swr_convert(swrContext, &out_buffer, 44100 * 2,                            (const uint8_t **) frame->data, frame->nb_samples);//                int av_samples_get_buffer_size(int *linesize, int nb_channels, int nb_samples,//                                               enum AVSampleFormat sample_fmt, int align);                int size = av_samples_get_buffer_size(NULL, out_channer_nb, frame->nb_samples, AV_SAMPLE_FMT_S16, 1);                *pcm = out_buffer;                *pcm_size = size;                break;            }        }    }    return 0;}void realseFFmpeg(){    av_free_packet(packet);    av_free(out_buffer);    av_frame_free(&frame);    swr_free(&swrContext);    avcodec_close(avCodecContext);    avformat_close_input(&avFormatContext);}

2.native-lib.h添加如下代码

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

3.修改CMakeLists.txt

add_library添加：src /main/cpp/FFmpegMusic.cpp

修改前：

add_library( native-lib             SHARED             src/main/cpp/native-lib.cpp             )

修改后：

add_library( native-lib             SHARED             src/main/cpp/native-lib.cpp             src/main/cpp/FFmpegMusic.cpp             )

target_link_libraries添加OpenSLES:

修改前：

target_link_libraries( native-lib                       avcodec-56                       avdevice-56                       avformat-56                       avutil-54                       swresample-1                       swscale-3                       -landroid                       ${log-lib} )

修改后：

target_link_libraries( native-lib                       avcodec-56                       avdevice-56                       avformat-56                       avutil-54                       swresample-1                       swscale-3                       OpenSLES                       -landroid                       ${log-lib} )

4.native-lib.h中添加方法：

JNIEXPORT void JNICALL Java_com_test_ffmpeg_AudioPlayer_openSlesPlay(JNIEnv *env, jobject instance);

5.native-lib.cpp实现

SLObjectItf slObjectItf = NULL;SLEngineItf slEngineItf = NULL;//混音器SLObjectItf pMix = NULL;SLEnvironmentalReverbItf slEnvironmentalReverbItf = NULL;SLEnvironmentalReverbSettings settings = SL_I3DL2_ENVIRONMENT_PRESET_DEFAULT;//播放器SLObjectItf bgPlayerObject;SLPlayItf  bqPlayerPlay;//队列缓冲区SLAndroidSimpleBufferQueueItf bqPlayerQueue;//音量对象SLVolumeItf bqPalyerVolume;//只要喇叭一读完  就会回调此函数，添加pcm数据到缓冲区void *buffer;size_t bufferSize = 0;void bqPlayerCallBack(SLAndroidSimpleBufferQueueItf bq, void *context){    bufferSize = 0;    getPcm(&buffer, &bufferSize);    if(buffer != NULL && 0 != bufferSize){        //播放的关键地方        SLresult sLresult = (*bqPlayerQueue)->Enqueue(bqPlayerQueue, buffer, bufferSize);        LOGI("正在播放 %d", bufferSize);    } else{        LOGI("播放结束 %d", bufferSize)        realseFFmpeg();    }};void JNICALL Java_com_test_ffmpeg_AudioPlayer_openSlesPlay(JNIEnv *env, jobject instance) {    //初始化一个引擎    SLresult sLresult;//    SL_API SLresult SLAPIENTRY slCreateEngine(//            SLObjectItf             *pEngine,//            SLuint32                numOptions,//            const SLEngineOption    *pEngineOptions,//            SLuint32                numInterfaces,//            const SLInterfaceID     *pInterfaceIds,//            const SLboolean         * pInterfaceRequired//    );    slCreateEngine(&slObjectItf, 0, NULL, 0, NULL, NULL);    (*slObjectItf)->Realize(slObjectItf, SL_BOOLEAN_FALSE);//    SLresult (*GetInterface) (//            SLObjectItf self,//            const SLInterfaceID iid,//            void * pInterface//    );    //获取引擎接口    sLresult = (*slObjectItf)->GetInterface(slObjectItf, SL_IID_ENGINE, &slEngineItf);    LOGI("引擎地址%p    sLresult  %d", slEngineItf, sLresult);    //创建混音器//    SLresult (*CreateOutputMix) (//            SLEngineItf self,//            SLObjectItf * pMix,//            SLuint32 numInterfaces,//            const SLInterfaceID * pInterfaceIds,//            const SLboolean * pInterfaceRequired//    );    (*slEngineItf)->CreateOutputMix(slEngineItf, &pMix, 0, 0, 0);    (*pMix)->Realize(pMix, SL_BOOLEAN_FALSE);    //设置环境混响    sLresult = (*pMix)->GetInterface(pMix, SL_IID_ENVIRONMENTALREVERB, &slEnvironmentalReverbItf);    LOGI("sLresult 1 %d", sLresult);    if(SL_RESULT_SUCCESS == sLresult){//        SLresult (*SetEnvironmentalReverbProperties) (//                SLEnvironmentalReverbItf self,//                const SLEnvironmentalReverbSettings *pProperties//        );        (*slEnvironmentalReverbItf)->SetEnvironmentalReverbProperties(slEnvironmentalReverbItf, &settings);    }    //初始化ffmpeg    int rate;    int channels;    createFFmpeg(&rate, &channels);    LOGI("%s", "初始化FFMPEG完毕");    SLDataLocator_AndroidBufferQueue androidBufferQueue = {SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, 2};//    typedef struct SLDataFormat_PCM_ {//        SLuint32 formatType;//        SLuint32 numChannels;//        SLuint32 samplesPerSec;//        SLuint32 bitsPerSample;//        SLuint32 containerSize;//        SLuint32 channelMask;//        SLuint32endianness;//    } SLDataFormat_PCM;    SLDataFormat_PCM pcm = {            SL_DATAFORMAT_PCM,            channels,            SL_SAMPLINGRATE_44_1,            SL_PCMSAMPLEFORMAT_FIXED_16,            SL_PCMSAMPLEFORMAT_FIXED_16,            SL_SPEAKER_FRONT_LEFT|SL_SPEAKER_FRONT_RIGHT,            SL_BYTEORDER_LITTLEENDIAN    };//    typedef struct SLDataSource_ {//        void *pLocator;//        void *pFormat;//    } SLDataSource;    SLDataSource slDataSource = {&androidBufferQueue, &pcm};    //设置混音器//    typedef struct SLDataLocator_OutputMix {//        SLuint32 locatorType;//        SLObjectItfoutputMix;//    } SLDataLocator_OutputMix;    SLDataLocator_OutputMix outputMix = {SL_DATALOCATOR_OUTPUTMIX, pMix};//    typedef struct SLDataSink_ {//        void *pLocator;//        void *pFormat;//    } SLDataSink;    SLDataSink audioSnk = {&outputMix, NULL};    const SLInterfaceID  ids[3] = {SL_IID_BUFFERQUEUE, SL_IID_EFFECTSEND, SL_IID_VOLUME};    const SLboolean req[3] = {SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE};    //混音器关联    //创建一个播放器//    SLresult (*CreateAudioPlayer) (//            SLEngineItf self,//            SLObjectItf * pPlayer,//            SLDataSource *pAudioSrc,//            SLDataSink *pAudioSnk,//            SLuint32 numInterfaces,//            const SLInterfaceID * pInterfaceIds,//            const SLboolean * pInterfaceRequired//    );    sLresult = (*slEngineItf)->CreateAudioPlayer(slEngineItf, &bgPlayerObject, &slDataSource, &audioSnk, 3, ids, req);    sLresult = (*bgPlayerObject)->Realize(bgPlayerObject, SL_BOOLEAN_FALSE);    //创建一个播放器接口    sLresult = (*bgPlayerObject)->GetInterface(bgPlayerObject, SL_IID_PLAY, &bqPlayerPlay);    //注册缓冲区    sLresult = (*bgPlayerObject)->GetInterface(bgPlayerObject, SL_IID_BUFFERQUEUE, &bqPlayerQueue);    //设置接口回调    sLresult = (*bqPlayerQueue)->RegisterCallback(bqPlayerQueue, bqPlayerCallBack, NULL);    (*bgPlayerObject)->GetInterface(bgPlayerObject, SL_IID_VOLUME, &bqPalyerVolume);    (*bqPlayerPlay)->SetPlayState(bqPlayerPlay, SL_PLAYSTATE_PLAYING);    //播放第一帧    bqPlayerCallBack(bqPlayerQueue, NULL);}

6.AudioPlayer添加native方法

public native void openSlesPlay();

7.MainActivity调用：

                new Thread(new Runnable() {                    @Override                    public void run() {                        new AudioPlayer().openSlesPlay();                    }                }).start();