ftp下载文件过程中，对v3格式文件进行转换，转成wav格式，并返回给页面，下载和播放。
怎么实现。网上的本地转换代码确实可用，但是我对字节流、转码这一块不太懂，不知道有
没有大神来看看，怎么写？
下面是本地v3转wav的代码
package cn.sh.ideal.utils;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class V3ToWav {
private static V3ToWav v3ToWav;
private V3ToWav(){
}
public static V3ToWav getInstance(){
if(v3ToWav == null){
v3ToWav = new V3ToWav();
}
return v3ToWav;
}
private static final int WAV_HEAD = 36;// wav文件头长度
private static final int VF_ADPCM = 1;// 编码格式
private static final int BIT_RATE_VB_8 = 1;// 每个样本位数
private static final int BIT_RATE_VB_16 = 2;// 每个样本位数
private static final int RESET_VALUE = 48;
private static byte out_val;
/**
*
* @param inFile
* @param outFile
* @param voxFormat
* 格式 取值范围:VF_ADPCM = 1, VF_MULAW = 2, VF_ALAW = 3
* @param voxRate
* 采样率 取值范围：VR_6K = 6000, VR_8K = 8000
* @param bit_rate
* 位数 取值范围：VB_8 = 1, VB_16 = 2
* @return
*/
public static void voxConvert(String inFile, String outFile, int voxFormat,
int voxRate, int bit_rate) throws Exception {
if (outFile == null) {
outFile = inFile.substring(0, inFile.length() - 2);
outFile = outFile + "wav";
}
File outF = new File(outFile);
File inF = new File(inFile);
long inFileSize = inF.length();
if (voxFormat == VF_ADPCM) { // if using ADPCM input format...
inFileSize = inFileSize * 2;
}// change from bytes to samples
FileOutputStream filewriter = new FileOutputStream(outF, false);
String wavBegin = "RIFF";
filewriter.write(wavBegin.getBytes());// WAV 文件头
long wavLength = inFileSize * bit_rate + WAV_HEAD;
byte[] tmpArr = new byte[4];
longToIntBinary(wavLength, tmpArr, 0);
filewriter.write(tmpArr);// 文件总长度
String wavTag = "WAVEfmt ";
filewriter.write(wavTag.getBytes());// WAV 文件标识
int headLength = 16;
tmpArr = new byte[4];
longToIntBinary(headLength, tmpArr, 0);
filewriter.write(tmpArr);// size of .WAV file header
int wFormatTag = 1; // format tag (01 = Windows PCM)
tmpArr = new byte[2];
toShortBinary(wFormatTag, tmpArr, 0);
filewriter.write(tmpArr);// format tag (01 = Windows PCM)
int nChannels = 1; // channels (1=mono, 2=stereo)
tmpArr = new byte[2];
toShortBinary(nChannels, tmpArr, 0);
filewriter.write(tmpArr);// channels (1=mono, 2=stereo)
int nSamplesPerSec = voxRate; // samples per second
tmpArr = new byte[4];
longToIntBinary(nSamplesPerSec, tmpArr, 0);
filewriter.write(tmpArr);
int nAvgBytesPerSec = voxRate * bit_rate; // bytes per second
// during play
tmpArr = new byte[4];
longToIntBinary(nAvgBytesPerSec, tmpArr, 0);
filewriter.write(tmpArr);
int nBlockAlign = bit_rate; // bytes per sample
tmpArr = new byte[2];
toShortBinary(nBlockAlign, tmpArr, 0);
filewriter.write(tmpArr);// bytes per sample
int wBitsPerSample = 8 * bit_rate; // bits per sample
tmpArr = new byte[2];
toShortBinary(wBitsPerSample, tmpArr, 0);
filewriter.write(tmpArr);// bits per sample
/** ******以下是数据头********* */
String dataTag = "data";
filewriter.write(dataTag.getBytes());// data tag
long Datalen = inFileSize * bit_rate; // write size of .WAV data
// portion
tmpArr = new byte[4];
longToIntBinary(Datalen, tmpArr, 0);
filewriter.write(tmpArr);// 数据总长度
//FileInputStream fileReader = new FileInputStream(inF);
FileInputStream fileReader = new FileInputStream(inF);
byte[] outbytebuffer = new byte[20000];
int[] outintbuffer = new int[20000];
switch (voxFormat) {
case VF_ADPCM:// VF_ADPCM
{
short Sn = 0; // initialize the ADPCM variables
int SS = 16; // initialize the Step
int SSindex = 1;
int i = 0;
byte[] b = new byte[10000];
int outindex;
byte sample;// 一个采样样本
int allBytes = fileReader.available();
while (allBytes > 0) {
int thisRead = allBytes > 10000 ? 10000 : allBytes;
int bytes = fileReader.read(b, 0, thisRead);
allBytes -= thisRead;// 剩余可读的字节数
outindex = 0;
for (int index = 0; index < bytes; index++) {
sample = b[index];
byte highByte = (byte) (sample >>> 4 & 0xff);
byte lowByte = (byte) (sample & 0x0f);
/** *****开始高字节处理******** */
if ((highByte == 0) || (highByte == 8)) {
i++;
}
Object[] retVal = decode((byte) (sample >>> 4), Sn, SS,
SSindex);
Sn = ((Short) retVal[0]).shortValue();
SS = ((Integer) retVal[1]).intValue();
SSindex = ((Integer) retVal[2]).intValue();
int out_int;
if (bit_rate == BIT_RATE_VB_8) {// if 8 bits per sample...
out_int = Sn / 16;
if (out_int > 127) { // clip if above or below WAV
// bounds
out_int = 127;
}
if (out_int < -128) {
out_int = -128;
}
out_val = (byte) ((out_int - 128) & 0xff); // convert
// to
// .WAV format
outbytebuffer[outindex] = out_val; // write the output
// byte
} else {// else 16 bits per sample
out_int = Sn * 16; // rescale to 16 bits
outintbuffer[outindex] = out_int; // write the output
// int
}
outindex++;
if (i == RESET_VALUE) { // Reset ADPCM variables 48位时重置各个值
Sn = 0; // initialize the ADPCM variables
SS = 16; // initialize the Step
i = 0;
}
/** *******低字节处理********* */
if (lowByte == 0 || lowByte == 8) {
i++;
}
retVal = decode((byte) (sample & 0x0f), Sn, SS, SSindex);
Sn = ((Short) retVal[0]).shortValue();
SS = ((Integer) retVal[1]).intValue();
SSindex = ((Integer) retVal[2]).intValue();
if (bit_rate == BIT_RATE_VB_8) {// if 8 bits per sample...
out_int = Sn / 16;
if (out_int > 127) { // clip if above or below WAV
// bounds
out_int = 127;
}
if (out_int < -128) {
out_int = -128;
}
out_val = (byte) ((out_int - 128) & 0xff); // convert
// to
// .WAV format
outbytebuffer[outindex] = out_val; // write the output
// byte
} else {// else 16 bits per sample
out_int = Sn * 16; // rescale to 16 bits
outintbuffer[outindex] = out_int; // write the output
// int
}
outindex++;
if (i == RESET_VALUE) { // Reset ADPCM variables 48位时重置各个值
Sn = 0; // initialize the ADPCM variables
SS = 16; // initialize the Step
i = 0;
}
}
if (bit_rate == BIT_RATE_VB_8) {
filewriter.write(outbytebuffer);
} else {
for (int j = 0; j < outintbuffer.length; j++) {
byte[] arr = new byte[4];
longToIntBinary(outintbuffer[j], arr, 0);
filewriter.write(arr);
}
}
}
break;
}
default:
break;
}
fileReader.close();
filewriter.close();
}
/**
*
* @param sample
* @param Sn
* @param ss
* 引用变量
* @param SSindex
* 引用变量
* @return
*/
private static Object[] decode(byte sample, short Sn, int SS, int SSindex) {
Object[] retArr = new Object[3];
int[] SSadjust = new int[] { -1, -1, -1, -1, 2, 4, 6, 8 };
// Calculated stepsizes per Dialogic Application Note 1366
int[] SStable = new int[] { 0, 16, 17, 19, 21, 23, 25, 28, 31, 34, 37,
41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143,
157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408, 449,
494, 544, 598, 658, 724, 796, 876, 963, 1060, 1166, 1282, 1411,
1552 };
int Mn = 0; // calculate the linear adjustment
if ((sample & 0x4) != 0) {
Mn = SS;
}
if ((sample & 0x2) != 0) {
Mn = Mn + (SS >>> 1);
}// div 2
if ((sample & 0x1) != 0) {
Mn = Mn + (SS >>> 2);
}// div 4
Mn = Mn + (SS >>> 3); // div 8
// 取Sample的符号位，即最高位
if ((sample & 0x8) != 0) { // 最高位为1，则符号位为负
Sn = (short) (((int) Sn - Mn) & 0xffff); // ...subtract the
// adjustment
} else { // 符号位为正
Sn = (short) (((int) Sn + Mn) & 0xffff); // ...add the adjustment
}
if (Sn > 2047) { // adjust if sample too large...
Sn = 2047;
}
if (Sn < -2048) { // ...or too small
Sn = -2048;
}
// use as index into step size adjustment, adjust step size index
SSindex = SSindex + SSadjust[sample & 0x07];
if (SSindex < 1) { // keep SSindex within bounds...
SSindex = 1;
}
if (SSindex > 49) {
SSindex = 49;
}
SS = SStable[SSindex]; // get new step size from table
retArr[0] = Sn;
retArr[1] = SS;
retArr[2] = SSindex;
return retArr;
}
/**
* 整型转数组
*
* @param val
* @param array
* @param offset
*/
private static void longToIntBinary(long val, byte[] array, int offset) {
array[offset] = (byte) (val & 0xff);
array[offset + 1] = (byte) (val >>> 8 & 0xff);
array[offset + 2] = (byte) (val >>> 16 & 0xff);
array[offset + 3] = (byte) (val >>> 24 & 0xff);
}
private void byteToShortBinary(byte val, byte[] array, int offset) {
array[offset] = (byte) (val & 0xff);
array[offset + 1] = 0x0;
}
/**
* java中没有有符号类型，所以将超过0x7FFF的short类型保存为int类型。本方法提供了将有符号short类型
* 转换保存在字节数组中，占据两个字节
*
* @param val
* int
* @param array
* byte[]
* @param offset
* int
*/
private static void toShortBinary(int val, byte[] array, int offset) {
array[offset] = (byte) (val & 0xff);
array[offset + 1] = (byte) (val >>> 8 & 0xff);
}
public static void main(String[] args) {
String inFile = "E:\\HK006470083.V3";
String outFile = "E:\\test.wav";
try {
voxConvert(inFile, outFile, 1, 6000, 1);
} catch (Exception e) {
e.printStackTrace();
}
}
}
