Tone

Revision as of 21:27, 5 September 2015

Tone(float length, float frequency, int samplerate, int channels, string type, float level)

This will generate sound at a given frequency for a given length of time in seconds.

length

Length of time in seconds. Default = 10.0.

frequency

Tone frequency. Default = 440.

samplerate

Audio sample rate. Default = 48000.

channels

Number of audio channels. Default = 2.

type

"Silence", "Sine", "Noise", "Square", "Triangle" or "Sawtooth". Default = "Sine".

level

The amplitude of the waveform. Default = maximum = 1.0.

The audio sample type is 32-bit float. Use ConvertAudio if this is not what you want.

Tone(frequency=2, samplerate=48000, channels=2, type="sine", level=0.4)

In the figure above, a sinus is generated (on a gray clip with framerate 24 fps). The period of the waveform (in frames) is the framerate divided by frequency (or fps/freq, which is 24/2=12 frames in our example). The part of the graph which is light-green represents all samples of the frame under consideration (which is frame 1 here). The number of samples in a particular frame is given by the samplerate divided by the framerate (which is 48000/24 = 2000 samples in our example). (Note that the bars are made with Histogram and the graph with the AudioGraph plugin.)

More generally, the waveform above is described by

g(n,s) = level * sin(2*pi*(frequency*n/framerate + s*frequency/samplerate))

with "n" the frame and "s" the sample under consideration (note that s runs from 0 to samplerate/framerate - 1).

In the example above, this reduces to

g(n,s) = 0.4 * sin(2*pi*(2*n/24 + s*2/48000))

with "n" the frame and "s" the sample under consideration (note that s runs from 0 to 1999).

Changes: