save pcm to wav format

WaveHelper.java

    public class WaveHelper {
        private File mFile;
        private int mSample;
        private int mChannel;
        private int mSampleBits;
        private LittleEndianDataOutputStream mDos;

        public WaveHelper(File file, int channel, int sample, int encoding) {
            mFile = file;
            mSample = sample;
            mChannel = getChannel(channel);
            mSampleBits = getSampleBits(encoding);
        }

        public void write(short[] data) throws IOException {
            if (null == mDos) {
                mDos = new LittleEndianDataOutputStream(new BufferedOutputStream(new FileOutputStream(mFile)));
                writeHeader();
            }
            for (short d : data)
                mDos.writeShort(d);
        }

        public void finish() throws IOException {
            mDos.close();

            RandomAccessFile f = new RandomAccessFile(mFile, "rw");
            f.seek(4);
            f.write(be2le((int) (mFile.length() - 8)));
            f.seek(40);
            f.write(be2le((int) (mFile.length() - 44)));
            f.close();
        }

        private int getChannel(int channel) {
            switch (channel) {
                case AudioFormat.CHANNEL_OUT_STEREO:
                    return 2;
                case AudioFormat.CHANNEL_OUT_MONO:
                default:
                    return 1;
            }
        }

        private int getSampleBits(int encoding) {
            switch (encoding) {
                case AudioFormat.ENCODING_PCM_8BIT:
                    return 8;
                case AudioFormat.ENCODING_PCM_16BIT:
                    return 16;
                case AudioFormat.ENCODING_PCM_FLOAT:
                default:
                    return 32;
            }
        }

        /**
         * see also: http://www.topherlee.com/software/pcm-tut-wavformat.html
         */
        private void writeHeader() throws IOException {
            mDos.writeBytes("RIFF");
            mDos.writeInt(0x0000);
            mDos.writeBytes("WAVE");
            mDos.writeBytes("fmt ");
            mDos.writeInt(16);
            mDos.writeShort(1);
            mDos.writeShort(mChannel);
            mDos.writeInt(mSample);
            mDos.writeInt(mSample* mChannel * mSampleBits / 8);
            mDos.writeShort(mSampleBits * mChannel / 8);
            mDos.writeShort(mSampleBits);
            mDos.writeBytes("data");
            mDos.writeInt(0x0000);
        }

        /**
         * big endian to little endian
         */
        private byte[] be2le(int value) {
            byte[] result = new byte[4];
            result[3] = (byte)(value >> 24);
            result[2] = (byte)((value << 8) >> 24);
            result[1] = (byte)((value << 16) >> 24);
            result[0] = (byte)((value << 24) >> 24);
            return result;
        }
    }