sine

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.

Command line examples

• Generate a simple 440 Hz sine wave:

  sine
  

• 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)))'
  

Audio Sinks

Below is a description of the currently available audio sinks.