一. MainActivity

public class MainActivity extends AppCompatActivity {
    private AudioTrack audioTrack;
    static {
        System.loadLibrary("native-lib");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        checkPermission();
        Button btn = (Button)findViewById(R.id.btn);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                File file = new File(Environment.getExternalStorageDirectory(), "input.mp3");
                playSound(file.getAbsolutePath());
            }
        });
    }

    public boolean checkPermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && checkSelfPermission(
                Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            requestPermissions(new String[]{
                    Manifest.permission.READ_EXTERNAL_STORAGE,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE,
                    Manifest.permission.CAMERA
            }, 1);

        }
        return false;
    }

    public native void playSound(String input);

    public void createTrack(int sampleRateInHz,int nb_channals) {
        Log.e("liuyi", "createTrack");
        int channaleConfig;
        if (nb_channals == 1) {
            channaleConfig = AudioFormat.CHANNEL_OUT_MONO;
        } else if (nb_channals == 2) {
            channaleConfig = AudioFormat.CHANNEL_OUT_STEREO;
        }else {
            channaleConfig = AudioFormat.CHANNEL_OUT_MONO;
        }
        int buffersize= AudioTrack.getMinBufferSize(sampleRateInHz,
                channaleConfig, AudioFormat.ENCODING_PCM_16BIT);
        audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,sampleRateInHz,channaleConfig, AudioFormat.ENCODING_PCM_16BIT
                ,buffersize,
                AudioTrack.MODE_STREAM);
        audioTrack.play();
    }

    public void playTrack(byte[] buffer, int lenth) {
        Log.e("liuyi", "playTrack");
        if (audioTrack != null && audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PLAYING) {
            audioTrack.write(buffer, 0, lenth);
        }
    }
}

二. native-lib.cpp

#include <jni.h>
#include <string>

extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/imgutils.h"
#include "libswscale/swscale.h"
#include <libavutil/time.h>
#include "libswresample/swresample.h"
}
#include <android/log.h>
#include <android/native_window_jni.h>
#define LOGD(...) __android_log_print(ANDROID_LOG_INFO,"liuyi",__VA_ARGS__)
#define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR, "liuyi", __VA_ARGS__)
static AVFormatContext *avFormatContext;
static AVCodecContext *avCodecContext;
AVCodec *vCodec;
ANativeWindow* nativeWindow;
ANativeWindow_Buffer windowBuffer;
static AVPacket *avPacket;
static AVFrame *avFrame, *rgbFrame;
uint8_t *outbuffer;
struct SwsContext *swsContext;

extern "C"
JNIEXPORT void JNICALL
Java_com_luisliuyi_demo_ffmpeg_MainActivity_playSound(JNIEnv *env, jobject instance, jstring input_) {
    const char *input = env->GetStringUTFChars(input_, 0);

    av_register_all();

    AVFormatContext *pFormatCtx = avformat_alloc_context();
    if (avformat_open_input(&pFormatCtx, input, NULL, NULL) != 0) {
        LOGE("%s","打开输入音频文件失败");
        return;
    }

    if(avformat_find_stream_info(pFormatCtx,NULL) < 0){
        LOGE("%s","获取音频信息失败");
        return;
    }

    int audio_stream_idx=-1;
    int i=0;
    for (int i = 0; i < pFormatCtx->nb_streams; ++i) {
        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
            LOGE("  找到音频id %d", pFormatCtx->streams[i]->codec->codec_type);
            audio_stream_idx=i;
            break;
        }
    }

    AVCodecContext *pCodecCtx= pFormatCtx->streams[audio_stream_idx]->codec;
    //获取解码器
    AVCodec *pCodex = avcodec_find_decoder(pCodecCtx->codec_id);
    //打开解码器
    if (avcodec_open2(pCodecCtx, pCodex, NULL)<0) {
        return;
    }

    AVPacket *packet = (AVPacket *)av_malloc(sizeof(AVPacket));
    AVFrame *frame = av_frame_alloc();

    int out_channer_nb = av_get_channel_layout_nb_channels(AV_CH_LAYOUT_STEREO);

    //转换器上下文
    SwrContext *swrContext = swr_alloc();
    uint64_t  out_ch_layout=AV_CH_LAYOUT_STEREO;
    enum AVSampleFormat out_formart=AV_SAMPLE_FMT_S16;
    int out_sample_rate = pCodecCtx->sample_rate;
    swr_alloc_set_opts(swrContext, out_ch_layout, out_formart, out_sample_rate,
            pCodecCtx->channel_layout, pCodecCtx->sample_fmt, pCodecCtx->sample_rate, 0,NULL
    );

    swr_init(swrContext);

    uint8_t *out_buffer = (uint8_t *) av_malloc(44100 * 2);

    jclass david_player = env->GetObjectClass(instance);
    jmethodID createAudio = env->GetMethodID(david_player, "createTrack", "(II)V");
    env->CallVoidMethod(instance, createAudio, 44100, out_channer_nb);
    jmethodID audio_write = env->GetMethodID(david_player, "playTrack", "([BI)V");

    while (av_read_frame(pFormatCtx, packet) >= 0) {
        if (packet->stream_index == audio_stream_idx) {
            int ret = avcodec_send_packet(pCodecCtx, packet);
            if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF){
                LOGE("解码出错");
                break;
            }
            ret = avcodec_receive_frame(pCodecCtx, frame);
            if (ret == AVERROR(EAGAIN)) {
                continue;
            } else if (ret < 0) {
                break;
            }
            if (ret>=0) {
                if (ret>=0) {
                    swr_convert(swrContext, &out_buffer, 44100 * 2, (const uint8_t **) (frame->data),
                                frame->nb_samples);
                    int size = av_samples_get_buffer_size(NULL, out_channer_nb, frame->nb_samples,
                                                          AV_SAMPLE_FMT_S16, 1);
                                    jbyteArray audio_sample_array = env->NewByteArray(size);
                    env->SetByteArrayRegion(audio_sample_array, 0, size,
                                        reinterpret_cast<const jbyte *>(out_buffer));
                    env->CallVoidMethod(instance, audio_write, audio_sample_array, size);
                    env->DeleteLocalRef(audio_sample_array);
                }
            }
        }
    }
    av_frame_free(&frame);
    av_free(packet);
    swr_free(&swrContext);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);
    env->ReleaseStringUTFChars(input_, input);
}

三.代码地址

https://gitee.com/luisliuyi/android-ffmpeg02.git