java pcm轉aac

import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaFormat;
import android.util.Log;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;

/**
 * pcm轉AAC編碼
 * Created by gj on 2017/4/7.
 */

public class AacEncode {

    private MediaCodec mediaCodec;
    private String mediaType = "OMX.google.aac.encoder";
    //解碼后保存文件
    private File file;
    ByteBuffer[] inputBuffers = null;
    ByteBuffer[] outputBuffers = null;
    MediaCodec.BufferInfo bufferInfo;

    FileOutputStream encFi = null;
    //pts時間基數
    long presentationTimeUs = 0;

    //創建一個輸出流用來輸出轉換的數據
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

    public AacEncode() {
    }

   //設置輸出路徑 
　　public void setOutputPath(String outPath){
        File file = new File(outPath);
        try {
            encFi = new FileOutputStream(file);

        }catch (IOException e){
            e.printStackTrace();
        }
    }

    public void start(){
        try {
            mediaCodec = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_AUDIO_AAC);
            //mediaCodec = MediaCodec.createByCodecName(mediaType);
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 設置音頻采樣率，44100是目前的標准，但是某些設備仍然支持22050，16000，11025
        final int kSampleRates[] = {8000, 11025, 22050, 44100, 48000};
        //比特率 聲音中的比特率是指將模擬聲音信號轉換成數字聲音信號后，單位時間內的二進制數據量，是間接衡量音頻質量的一個指標
        final int kBitRates[] = {64000, 96000, 128000};

        //初始化   此格式使用的音頻編碼技術、音頻采樣率、使用此格式的音頻信道數（單聲道為 1，立體聲為 2）
        MediaFormat mediaFormat = MediaFormat.createAudioFormat(
                MediaFormat.MIMETYPE_AUDIO_AAC, kSampleRates[3], 2);

        mediaFormat.setString(MediaFormat.KEY_MIME, MediaFormat.MIMETYPE_AUDIO_AAC);
        mediaFormat.setInteger(MediaFormat.KEY_AAC_PROFILE,MediaCodecInfo.CodecProfileLevel.AACObjectLC);
        //比特率 聲音中的比特率是指將模擬聲音信號轉換成數字聲音信號后，單位時間內的二進制數據量，是間接衡量音頻質量的一個指標
        mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, kBitRates[1]);

        //傳入的數據大小
        mediaFormat.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, 4096);// It will
        //設置相關參數
        mediaCodec.configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
        //開始
        mediaCodec.start();

        inputBuffers = mediaCodec.getInputBuffers();
        outputBuffers = mediaCodec.getOutputBuffers();
        bufferInfo = new MediaCodec.BufferInfo();
    }

    /**
     * 關閉釋放資源
     *
     * @author：gj
     * @date: 2017/4/25
     * @time: 16:19
     **/
    public void close() {
        try {
            mediaCodec.stop();
            mediaCodec.release();
            outputStream.flush();
            outputStream.close();
            encFi.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 開始編碼
     * offset 偏移量
　　　* size   數據大小
     **/
    public void encode(byte[] input, int offset, int size) throws Exception {

        int inputBufferIndex = mediaCodec.dequeueInputBuffer(-1);//其中需要注意的有dequeueInputBuffer（-1），參數表示需要得到的毫秒數，-1表示一直等，0表示不需要等，傳0的話程序不會等待，但是有可能會丟幀。
        if (inputBufferIndex >= 0) {
            ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];
            inputBuffer.clear();
            inputBuffer.put(input);
            inputBuffer.limit(input.length);

            //計算pts
            long pts = computePresentationTime(presentationTimeUs);

            mediaCodec.queueInputBuffer(inputBufferIndex, offset, size, pts, 0);
            presentationTimeUs += 1;
        }

        int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);

        while (outputBufferIndex >= 0) {
            int outBitsSize = bufferInfo.size;
            int outPacketSize = outBitsSize + 7; // 7 is ADTS size
            ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];

            outputBuffer.position(bufferInfo.offset);
            outputBuffer.limit(bufferInfo.offset + outBitsSize);

            //添加ADTS頭
            byte[] outData = new byte[outPacketSize];
            addADTStoPacket(outData, outPacketSize);

            outputBuffer.get(outData, 7, outBitsSize);
            outputBuffer.position(bufferInfo.offset);

            //寫到輸出流里
            outputStream.write(outData);

            // Log.e("AudioEncoder", outData.length + " bytes written");

            mediaCodec.releaseOutputBuffer(outputBufferIndex, false);
            outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);
        }
        //輸出流的數據轉成byte[]
        byte[] out = outputStream.toByteArray();
        encFi.write(out);
        //寫完以后重置輸出流，否則數據會重復
        outputStream.flush();
        outputStream.reset();

    }

    /**
     * 給編碼出的aac裸流添加adts頭字段
     *
     * @param packet    要空出前7個字節，否則會搞亂數據
     * @param packetLen
     */
    private void addADTStoPacket(byte[] packet, int packetLen) {
        int profile = 2;  //AAC LC
        int freqIdx = 4;  //44.1KHz
        int chanCfg = 2;  //CPE
        packet[0] = (byte) 0xFF;
        packet[1] = (byte) 0xF9;
        packet[2] = (byte) (((profile - 1) << 6) + (freqIdx << 2) + (chanCfg >> 2));
        packet[3] = (byte) (((chanCfg & 3) << 6) + (packetLen >> 11));
        packet[4] = (byte) ((packetLen & 0x7FF) >> 3);
        packet[5] = (byte) (((packetLen & 7) << 5) + 0x1F);
        packet[6] = (byte) 0xFC;
    }


    //計算PTS，實際上這個pts對應音頻來說作用並不大，設置成0也是沒有問題的
    private long computePresentationTime(long frameIndex) {
        return frameIndex * 90000 * 1024 / 44100;
    }
}


//調用

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class PcmAac extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_pcm_aac);

        AacEncode aacEncode = new AacEncode();

        aacEncode.start();
        aacEncode.setOutputPath("/data/local/tmp/yi.aac");
        int size = 4096;
        byte[] inBuffer = new byte[size];
        File inFile = new File("/data/local/tmp/yi.pcm");
        FileInputStream in = null;
        int len = 0;
        try {
            in = new FileInputStream(inFile);
            while ((len = in.read(inBuffer, 0, 2048)) > 0){

                aacEncode.encode(inBuffer, 1024, len);
            }
            aacEncode.close();
        }catch (IOException e){
            e.printStackTrace();
        }catch (java.lang.Exception e){
            e.printStackTrace();
        }
    }
}