java 音频格式转换
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Conversion of Audio Format
提问by Vijay Suryawanshi
I am having trouble in converting the audio format of a WAV file.
我在转换 WAV 文件的音频格式时遇到问题。
I am recording sound from my microphone and the sound is recorded in the following format: PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame
我正在从我的麦克风录制声音，声音以以下格式录制：PCM_SIGNED 44100.0 Hz，16 位，单声道，2 字节/帧
I want to convert the above format to, ULAW 8000.0 Hz, 8 bit, mono, 1 bytes/frame
我想将上述格式转换为 ULAW 8000.0 Hz, 8 bit, mono, 1 bytes/frame
I am using the following code,
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
And I am getting the following error,
我收到以下错误，
java.lang.IllegalArgumentException: Unsupported conversion: ULAW 8000.0 Hz, 8 bit, mono, 1 bytes/frame, from PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian
java.lang.IllegalArgumentException：不支持的转换：ULAW 8000.0 Hz，8 位，单声道，1 字节/帧，来自 PCM_SIGNED 44100.0 Hz，16 位，单声道，2 字节/帧，小端
Can someone please help me solve this problem!!!
谁能帮我解决这个问题！！！
Thanks a ton!!!
万分感谢！！！
采纳答案by Andrzej Doyle
Did you take a look at the documentation?
你看文档了吗？
Throws: IllegalArgumentException - if the conversion is not supported #see #getTargetEncodings(AudioFormat)
抛出：IllegalArgumentException - 如果不支持转换#see #getTargetEncodings(AudioFormat)
Not every system will have sufficient codecs installed to transform to the specific format you've asked for. You've assumed yours does, but it's throwing the exception because it can't transform to that format.
并非每个系统都会安装足够的编解码器来转换为您要求的特定格式。你已经假设你的，但它抛出异常，因为它无法转换为该格式。
You can use getTargetEncodingsto check the suitability of a given format programatically, without relying on an exception, and then can take appropriate action if you desired output format isn't available (e.g. fall back to another one, present the user with feedback that this is impossible, etc.).
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，然后可以在所需的输出格式不可用时采取适当的措施（例如退回到另一种格式，向用户提供反馈，这是不可能等）。
回答by 11101101b
This class may help you. I found it 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;
}
}
