getFft

public int getFft (byte[] fft)

引入自：API 级别9

Returns a frequency capture of currently playing audio content.

This method must be called when the Visualizer is enabled.

The capture is an 8-bit magnitude FFT, the frequency range covered being 0 (DC) to half of the sampling rate returned by getSamplingRate(). The capture returns the real and imaginary parts of a number of frequency points equal to half of the capture size plus one.

Note: only the real part is returned for the first point (DC) and the last point (sampling frequency / 2).

The layout in the returned byte array is as follows:

• n is the capture size returned by getCaptureSize()
• Rfk, Ifk are respectively the real and imaginary parts of the kth frequency component
• If Fs is the sampling frequency retuned by getSamplingRate() the kth frequency is: (k*Fs)/(n/2)

Index	0	1	2	3	4	5	...	n - 2	n - 1
Data	Rf0	Rf(n/2)	Rf1	If1	Rf2	If2	...	Rf(n-1)/2	If(n-1)/2

 

参数

fft	array of bytes where the FFT should be returned

返回值

• SUCCESS in case of success, ERROR_NO_MEMORY, ERROR_INVALID_OPERATION or ERROR_DEAD_OBJECT in case of failure.

抛出

IllegalStateException