Librosa音频处理（二）_综合

对音频信号的处理可以通过 librosa.ifgram 方法获取 stft 短时傅立叶变换的矩阵，对该矩阵进行修改搬移，再进行 istft 逆转换获得处理后的音频信号。

y, sr = librosa.load(path)
frequencies, D = librosa.ifgram(y, sr=sr)
'''中间对D进行处理就行了
'''
y = librosa.istft(D)

D为stft变换的矩阵，x 轴为时间序列，y轴为频率序列坐标对应frequencies，值为幅度。

由于D类型为numpy.ndarray，所以我们很方便就可以通过numpy库对矩阵处理。

回音
```
D = np.repeat(D, 2, axis=1)
```
间断
```
D[:,::2] = 0
```
音色
```
D = np.roll(D, 50, axis=0)
```

压缩频率

def _pool(D, poolsize):x = D.shape[1] // poolsizerestsize = D.shape[1] % poolsizeif restsize > 0:x += 1rightlist = np.zeros([ D.shape[0], poolsize-restsize])D = np.c_[D, rightlist]D = D.reshape( (-1, poolsize) )D = D.sum(axis=1).reshape(-1,x)return Ddef rewardshape(D, shape):x = shape[0] - D.shape[0]y = shape[1] - D.shape[1]if x > 0:bottomlist = np.zeros([x, D.shape[1]])D = np.r_[D, bottomlist]if y > 0:rightlist = np.zeros([ D.shape[0], y])D = np.c_[D, rightlist]return Ddef pool(D, size=(3,3), shapeed=False):_shape = D.shapeif size[1] > 1:D = _pool(D, size[1])if size[0] > 1:D = _pool(D.T, size[0]).Tif shapeed:D = rewardshape(D, _shape)return D