次のコードは、正弦波を含むFileを作成する必要があります。典型的な周波数(220Hz、440Hz、880Hz)ではそれは大きくなりますが、他の多くの周波数では、225Hz、883Hzなどとは異なります。任意の周波数に対して正弦波を得るにはどうすればよいですか?正弦波とユーザー定義の持続時間と周波数で.wavファイルを生成する方法はありますか?
import java.lang.Math;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
public class CreateSine
{
static String fileNameString = "Sine.wav";
static File file = new File(fileNameString);
static String filePath = file.getAbsolutePath();
static RandomAccessFile raw;
static int byteCount = 0;
static double pow215 = Math.pow(2, 15);
static float freq = 440.0f;
static int sRate = 44100;
static int bitDepth = 16;
static int nChannels = 1;
static int dur = 1;
static float changeRate = (float)((2.0 * Math.PI * freq)/sRate);
public static void main(String[] args)
{
try
{
raw = new RandomAccessFile(filePath, "rw");
raw.setLength(0); // Set file length to 0, to prevent unexpected behavior in case the file already existed
raw.writeBytes("RIFF");
raw.writeInt(0); // Final file size not known yet, write 0. This is = sample count + 36 bytes from header.
raw.writeBytes("WAVE");
raw.writeBytes("fmt ");
raw.writeInt(Integer.reverseBytes(16)); // Sub-chunk size, 16 for PCM
raw.writeShort(Short.reverseBytes((short) 1)); // AudioFormat, 1 for PCM
raw.writeShort(Short.reverseBytes((short)nChannels));// Number of channels, 1 for mono, 2 for stereo
raw.writeInt(Integer.reverseBytes(sRate)); // Sample rate
raw.writeInt(Integer.reverseBytes(sRate*bitDepth*nChannels/8)); // Byte rate, SampleRate*NumberOfChannels*bitDepth/8
raw.writeShort(Short.reverseBytes((short)(nChannels*bitDepth/8))); // Block align, NumberOfChannels*bitDepth/8
raw.writeShort(Short.reverseBytes((short)bitDepth)); // Bit Depth
raw.writeBytes("data");
raw.writeInt(0); // Data chunk size not known yet, write 0. This is = sample count.
}
catch(IOException e)
{
System.out.println("I/O exception occured while writing data");
}
for (int i = 0; i < sRate*dur; i++)
{
writeSample((float)Math.sin(i * changeRate));
}
closeFile();
System.out.print("Finished");
}
static void writeSample(float floatValue)
{
try
{
short hexSample = (short)((floatValue * pow215));
raw.writeShort(Short.reverseBytes(hexSample));
byteCount += 2;
}
catch(IOException e)
{
System.out.println("I/O exception occured while writing data");
}
}
static void closeFile()
{
try
{
raw.seek(4); // Write size to RIFF header
raw.writeInt(Integer.reverseBytes(byteCount + 36));
raw.seek(40); // Write size to Subchunk2Size field
raw.writeInt(Integer.reverseBytes(byteCount));
raw.close();
}
catch(IOException e)
{
System.out.println("I/O exception occured while closing output file");
}
}
}
ありがとうございました。