sine - FFmpeg 7.1 / Sources / Audio

Generate an audio signal made of a sine wave with amplitude 1/8.

The audio signal is bit-exact.

The filter accepts the following options:

frequency, f

Set the carrier frequency. Default is 440 Hz.

beep_factor, b

Enable a periodic beep every second with frequency beep_factor times the carrier frequency. Default is 0, meaning the beep is disabled.

sample_rate, r

Specify the sample rate, default is 44100.

duration, d

Specify the duration of the generated audio stream.

samples_per_frame

Set the number of samples per output frame.

The expression can contain the following constants:

n: The (sequential) number of the output audio frame, starting from 0.
pts: The PTS (Presentation TimeStamp) of the output audio frame, expressed in TB units.
t: The PTS of the output audio frame, expressed in seconds.
TB: The timebase of the output audio frames.

Default is 1024.

Examples

Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:

sine=220:4:d=5
sine=f=220:b=4:d=5
sine=frequency=220:beep_factor=4:duration=5

Generate a 1 kHz sine wave following 1602,1601,1602,1601,1602 NTSC pattern:
```
sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
```