我有一個存儲在WAV文件中的生成噪聲,我打算在揚聲器上播放Android智能手機並錄製聲音並將其另存爲另一個使用同一智能手機的WAV文件(只有2個獨立的線程,1個用於播放,1個用於錄製)。我可以成功獲取錄製的WAV文件。但是當我在Matlab中繪製兩個WAV文件時,我在兩個圖之間有一個奇怪的差異,如你所見,記錄的信號具有比原始信號高得多的頻率。我無法用我自己的耳朵區分這兩個WAV文件。有人可以告訴我究竟造成這種差異的原因嗎?謝謝! My original wav file is here,My recorded WAV file is here,我的用於記錄聲音的代碼是:繪製錄製聲音時奇怪的頻率
private int bufferSizeInBytes = 0;
private int audioSource = MediaRecorder.AudioSource.MIC;
private static int sampleRateInHz = 48000;
private static int channelConfig = AudioFormat.CHANNEL_IN_STEREO;
private static int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
private void creatAudioRecord() {
bufferSizeInBytes = AudioRecord.getMinBufferSize(sampleRateInHz,
channelConfig, audioFormat);
audioRecord = new AudioRecord(audioSource, sampleRateInHz,
channelConfig, audioFormat, bufferSizeInBytes);
}
class AudioRecordThread implements Runnable {
@Override
public void run() {
writeDateTOFile2();
copyWaveFile(AudioName, NewAudioName);
}
}
private void writeDateTOFile2(byte[] audiodata) {
FileOutputStream fos = null;
int readsize = 0;
try {
File file = new File(AudioName2);
if (file.exists()) {
file.delete();
}
fos = new FileOutputStream(file);
} catch (Exception e) {
e.printStackTrace();
}
try {
fos.write(audiodata);
} catch (IOException e) {
e.printStackTrace();
}
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
@SuppressLint("NewApi")
private void copyWaveFile(String inFilename, String outFilename) {
FileInputStream in = null;
FileOutputStream out = null;
long totalAudioLen = 0;
long totalDataLen = totalAudioLen + 36;
long longSampleRate = sampleRateInHz;
int channels = 1;
long byteRate = 16 * sampleRateInHz * channels/8;
byte[] data = new byte[bufferSizeInBytes];
try {
in = new FileInputStream(inFilename);
out = new FileOutputStream(outFilename);
totalAudioLen = in.getChannel().size();
totalDataLen = totalAudioLen + 36;
WriteWaveFileHeader(out, totalAudioLen, totalDataLen,
longSampleRate, channels, byteRate);
while (in.read(data) != -1) {
out.write(data);
}
in.close();
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void WriteWaveFileHeader(FileOutputStream out, long totalAudioLen,
long totalDataLen, long longSampleRate, int channels, long byteRate)
throws IOException {
byte[] header = new byte[44];
header[0] = 'R'; // RIFF/WAVE header
header[1] = 'I';
header[2] = 'F';
header[3] = 'F';
header[4] = (byte) (totalDataLen & 0xff);
header[5] = (byte) ((totalDataLen >> 8) & 0xff);
header[6] = (byte) ((totalDataLen >> 16) & 0xff);
header[7] = (byte) ((totalDataLen >> 24) & 0xff);
header[8] = 'W';
header[9] = 'A';
header[10] = 'V';
header[11] = 'E';
header[12] = 'f'; // 'fmt ' chunk
header[13] = 'm';
header[14] = 't';
header[15] = ' ';
header[16] = 16; // 4 bytes: size of 'fmt ' chunk
header[17] = 0;
header[18] = 0;
header[19] = 0;
header[20] = 1; // format = 1
header[21] = 0;
header[22] = (byte) channels;
header[23] = 0;
header[24] = (byte) (longSampleRate & 0xff);
header[25] = (byte) ((longSampleRate >> 8) & 0xff);
header[26] = (byte) ((longSampleRate >> 16) & 0xff);
header[27] = (byte) ((longSampleRate >> 24) & 0xff);
header[28] = (byte) (byteRate & 0xff);
header[29] = (byte) ((byteRate >> 8) & 0xff);
header[30] = (byte) ((byteRate >> 16) & 0xff);
header[31] = (byte) ((byteRate >> 24) & 0xff);
header[32] = (byte) (2 * 16/8); // block align
header[33] = 0;
header[34] = 16; // bits per sample
header[35] = 0;
header[36] = 'd';
header[37] = 'a';
header[38] = 't';
header[39] = 'a';
header[40] = (byte) (totalAudioLen & 0xff);
header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
header[43] = (byte) ((totalAudioLen >> 24) & 0xff);
out.write(header, 0, 44);
}
而且我對在Matlab繪製這兩個WAV文件的代碼是:
[wave,fs]=wavread('jamming3.wav');
wave=wave(:,[1]);
t=0:1/fs:(length(wave)-1)/fs;
magnwave=abs(fft(wave));
phasewave=angle(fft(wave));
sub1_L=magnwave.*exp(i*phasewave);
sub1_L=ifft(sub1_L);
q=(abs(sub1_L).*cos(angle(sub1_L)))*(2^15-1);
q=q(1000:length(q),1);
% plot(q);
% axis([44000,45000,-2^15+1,+2^15-1]);
test = 950;
t=0:1/fs:(length(wave)-1)/fs;
z = t([1],:);
wave1=wave(:,[1])*(2^15-1);
figure; hold on;
grid on;
box on;
plot(1:length(q), q,'-g','Displayname','Original noise');
%scatter(1:length(wave1), wave1,5, [1 0 0],'Displayname','Noise sample');
%scatter(1:length(q),q(:,1)-wave1,5,'Displayname','Error');
%axis([test,test+200,-40000,40000]);
axis([0,300,-40000,40000]);
hold on;
legend show;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[wave,fs]=wavread('recorded noise2.wav');
wave=wave(:,[1]);
%wave=wave(1000:length(wave));
%sub1=sub1(1000:length(sub1));
t=0:1/fs:(length(wave)-1)/fs;
magnwave=abs(fft(wave));
phasewave=angle(fft(wave));
sub1_L=magnwave.*exp(i*phasewave);
sub1_L=ifft(sub1_L);
q1=(abs(sub1_L).*cos(angle(sub1_L)))*(2^15-1);
q1=q1(15252:length(q1),1);
% plot(q);
% axis([44000,45000,-2^15+1,+2^15-1]);
offsets = 0;
t=0:1/fs:(length(wave)-1)/fs;
z = t([1],:);
wave1=wave(:,[1])*(2^15-1);
figure; hold on;
grid on;
box on;
plot(1:length(q1), q1*1.25,'-g','Displayname','Recovered signal');
%scatter(1:length(wave1), wave1,5, [1 0 0],'Displayname','Noise sample');
%scatter(1:length(q),q(:,1)-wave1,5,'Displayname','Error');
axis([offsets,offsets+300,-40000,40000]);
%axis([0,300,-40000,40000]);
hold on;
legend show;
更新#1:很抱歉的混亂,我繪製的部分是我放入WAV文件進行同步的標題,所以我可以對它後面的數據進行進一步處理。
更新#2:我最近更新了我的代碼,使用語音識別通道錄製聲音,它看起來更好,但頻率仍然是問題。我的新記錄噪音也在上面的鏈接中更新。
更新#3:我剛剛通過使用size(x)顯示了這兩個wav文件在matlab中的確切大小,它顯示從原始文件提取的數組大約爲100k,並且記錄的wav文件僅僅是50k,基於這兩個文件的大小相同,我認爲這可能是問題所在。我的錄音過程有什麼問題嗎?
更新#4:我剛剛意識到錄製的wav文件是由智能手機生成的,不能用wavplay()函數直接在matlab中播放,是不是原因?在我上面的wav寫入功能中可能會出現一些問題,但它是生成WAV文件的標準方式:(更新#5:知道所有設備都支持44.1 kHz,所以我將原始信號更改爲44.1千赫,還是沒有好。:(
會變成這樣是由自動增益控制引起的?呵呵,我絕對聽到兩者有差別。 – PurpleAlien 2013-05-01 00:44:54
@PurpleAlien我以前從來沒有聽說過這個術語,根據維基百科的說法,這可能是原因,我該如何避免這種情況呢?謝謝 – 2013-05-01 00:48:33
@PurpleAlien我也注意到,如果我在我的桌面上播放它,它們有區別,但在我的智能手機上,兩個wav文件聽起來都是一樣的。 – 2013-05-01 00:54:55