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# Add a test-tone sine wave
- URL: https://ffmpeguru.com/add-a-test-tone-sine-wave/
- Published: 2026-09-01T09:00:00.000Z
- Updated: 2026-10-13T17:59:41.000Z
- Author: FFmpeguru
- Tags: ffmpeg

A pure sine wave at a known frequency is the simplest possible audio test signal. You use it to verify a speaker is wired correctly (left vs right), to calibrate a room's response, or to confirm an audio interface is passing signal at all. FFmpeg can generate one without an input file.

## The command

```
ffmpeg -f lavfi -i "sine=frequency=1000:duration=5" -c:a pcm_s16le test.wav
```

## What it does

The \`sine\` source filter generates a sine wave at the specified frequency for the specified duration. The default is a 440 Hz wave (concert A) at 0 dBFS; pass \`frequency=1000\` for a 1 kHz test tone, \`sample\_rate=48000\` to set the sample rate explicitly. The output is a raw audio file you can play in any audio player or pipe into a measurement tool.

## Requirements

No input file. The \`lavfi\` virtual input lets you use a source filter as the only input. The output codec \`pcm\_s16le\` is the standard 16-bit signed little-endian PCM, which is what every audio editor and player reads. No hardware, no special build.

## Things to avoid

- Forgetting \`-f lavfi\` before the \`-i\`. Without it, FFmpeg tries to interpret \`sine=frequency=...\` as a filename and errors out.
- Generating a tone at a frequency that is inaudible on your speakers. Below 20 Hz or above 20 kHz, the tone will be silent on consumer hardware.
- Using a single-frequency tone to test stereo balance. The test only confirms that the speaker is wired to the correct channel; for balance, use a pink noise source.
- Relying on the default duration. The default is 10 seconds; pass \`duration=5\` or \`duration=0.1\` to keep the file small for a quick test.