音频格式的转换
音频格式的转换
提问于 2012-05-09 19:30:01
我在转换WAV文件的音频格式时遇到了问题。
我正在用麦克风录音，录音格式如下: PCM_SIGNED 44100.0 Hz，16位，单声道，2字节/帧
我想把上面的格式转换成，ULAW 8000.0 Hz，8位，单声道，1字节/帧
我正在使用以下代码，
InputStream is = request.getInputStream();
AudioInputStream ais = AudioSystem.getAudioInputStream(is);
AudioFormat oldFormat = ais.getFormat();
AudioFormat newFormat = new AudioFormat(AudioFormat.Encoding.ULAW, 8000, 8, 1, 1, 8000, false) ;
AudioInputStream lowResAIS = AudioSystem.getAudioInputStream(newFormat, ais); //Getting the below Exception on this line我得到了下面的错误，
java.lang.IllegalArgumentException:不支持的转换: PCM_SIGNED 8000.0 Hz，8位，单声道，1字节/帧，从ULAW 44100.0 Hz，16位，单声道，2字节/帧，小端
有人能帮我解决这个问题吗！
万分感谢！
回答 2
Stack Overflow用户
回答已采纳
发布于 2012-05-09 19:37:07
你有没有看过documentation
抛出：IllegalArgumentException -如果不支持转换，请参阅#getTargetEncodings(AudioFormat)
并不是每个系统都安装了足够的编解码器来转换为您所要求的特定格式。您已经假设您的代码是这样的，但是它抛出了异常，因为它不能转换为这种格式。
您可以使用getTargetEncodings以编程方式检查给定格式的适用性，而不依赖于异常，然后如果您想要的输出格式不可用，则可以采取适当的操作(例如，回退到另一个格式，向用户提供反馈，这是不可能的，等等)。
Stack Overflow用户
发布于 2013-07-19 03:48:58
这门课可能会对你有所帮助。我发现它是here：
package uk.co.mmscomputing.sound;
import java.io.*;
public class CompressInputStream extends FilterInputStream{
/*
Convert mono PCM byte stream into A-Law u-Law byte stream
static AudioFormat alawformat= new AudioFormat(AudioFormat.Encoding.ALAW,8000,8,1,1,8000,false);
static AudioFormat ulawformat= new AudioFormat(AudioFormat.Encoding.ULAW,8000,8,1,1,8000,false);
PCM 8000.0 Hz, 16 bit, mono, SIGNED, little-endian
static AudioFormat pcmformat = new AudioFormat(8000,16,1,true,false);
*/
static private Compressor alawcompressor=new ALawCompressor();
static private Compressor ulawcompressor=new uLawCompressor();
private Compressor compressor=null;
public CompressInputStream(InputStream in, boolean useALaw)throws IOException{
super(in);
compressor=(useALaw)?alawcompressor:ulawcompressor;
}
public int read()throws IOException{
throw new IOException(getClass().getName()+".read() :\n\tDo not support simple read().");
}
public int read(byte[] b)throws IOException{
return read(b,0,b.length);
}
public int read(byte[] b, int off, int len)throws IOException{
int i,sample;
byte[] inb;
inb=new byte[len<<1]; // get 16bit PCM data
len=in.read(inb);
if(len==-1){return -1;};
i=0;
while(i<len){
sample = (inb[i++]&0x00FF);
sample |= (inb[i++]<<8);
b[off++]=(byte)compressor.compress((short)sample);
}
return len>>1;
}
}
abstract class Compressor{
protected abstract int compress(short sample);
}
/*
Mathematical Tools in Signal Processing with C++ and Java Simulations
by Willi-Hans Steeb
International School for Scientific Computing
*/
class ALawCompressor extends Compressor{
static final int cClip = 32635;
static final int[] ALawCompressTable ={
1,1,2,2,3,3,3,3,
4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,
5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7
};
protected int compress(short sample){
int sign;
int exponent;
int mantissa;
int compressedByte;
sign = ((~sample) >> 8) & 0x80;
if(sign==0){ sample *= -1;}
if(sample > cClip){ sample = cClip; }
if(sample >= 256){
exponent = ALawCompressTable[(sample >> 8) & 0x007F];
mantissa = (sample >> (exponent + 3) ) & 0x0F;
compressedByte = 0x007F & ((exponent << 4) | mantissa);
}else{
compressedByte = 0x007F & (sample >> 4);
}
compressedByte ^= (sign ^ 0x55);
return compressedByte;
}
}
class uLawCompressor extends Compressor{
static final int cClip = 32635;
static final int cBias = 0x84;
int[] uLawCompressTable ={
0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
};
protected int compress(short sample){
int sign;
int exponent;
int mantissa;
int compressedByte;
sign = (sample >> 8) & 0x80;
if(sign!=0){ sample *= -1;}
if(sample > cClip){ sample = cClip; }
sample += cBias;
exponent = uLawCompressTable[(sample >> 7) & 0x00FF];
mantissa = (sample >> (exponent + 3)) & 0x0F;
compressedByte = ~(sign | (exponent << 4) | mantissa);
return compressedByte&0x000000FF;
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/10515174
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