How to Use the FFmpeg showspectrum Filter

This article provides a practical guide on how to use the showspectrum filter in FFmpeg to convert audio files into visual spectrogram videos. You will learn the basic command structure, explore essential configuration parameters like resolution, color modes, and scaling, and view ready-to-use command examples for creating high-quality audio visualizations.

What is the showspectrum Filter?

The showspectrum filter in FFmpeg is a visualization tool that converts incoming audio signals into a video stream representing the audio frequency spectrum. It is highly customizable, allowing you to control how frequencies are scaled, colored, and displayed over time.

Basic Usage

To generate a video from an audio file using the default showspectrum settings, use the following basic command structure. This command takes an audio input, applies the filter, and pairs the generated video back with the original audio.

ffmpeg -i input.mp3 -filter_complex "[0:a]showspectrum=s=1280x720[v]" -map "[v]" -map 0:a output.mp4

Command Breakdown:

• -i input.mp3: Specifies the input audio file.
• -filter_complex "[0:a]showspectrum=s=1280x720[v]": Takes the audio track ([0:a]), applies the showspectrum filter with a resolution of 1280x720, and outputs the video stream as [v].
• -map "[v]" -map 0:a: Combines the newly created video stream and the original audio stream into the final output.
• output.mp4: The resulting video file.

Key Parameters and Customization

You can customize the look and behavior of the spectrogram by passing specific parameters to the showspectrum filter, separated by colons.

1. Set Video Resolution (size or s)

Defines the width and height of the output video. * Example: showspectrum=s=1920x1080 (Full HD)

2. Adjust Frequency Scale (scale)

Determines how frequencies are spaced vertically. * linear: Linear spacing (default). * log: Logarithmic spacing, which better represents how human ears perceive pitch. * sqrt: Square root spacing. * Example: showspectrum=scale=log

3. Change Color Schemes (color)

Specifies the color palette of the intensity levels. Available options include rainbow, cool, magma, intensity, and channel (different colors per audio channel). * Example: showspectrum=color=rainbow

4. Choose sliding mode (slide)

Controls how the spectrum moves across the screen. * flow: The spectrum scrolls from right to left. * scroll: The spectrum scrolls, leaving a trail. * replace: The drawing line wraps around the screen. * Example: showspectrum=slide=scroll

5. Multi-channel display (mode)

Controls how multiple audio channels are drawn. * combined: Channels are blended together. * separate: Each channel is drawn in its own row. * Example: showspectrum=mode=separate

Practical Examples

High-Definition Logarithmic Spectrogram

This command creates a 1080p video using a logarithmic frequency scale, which is ideal for musical analysis.

ffmpeg -i input.wav -filter_complex "[0:a]showspectrum=s=1920x1080:scale=log:color=intensity[v]" -map "[v]" -map 0:a -c:v libx264 -pix_fmt yuv420p output.mp4

Separate Channel Stereo Visualization

If you have a stereo track and want to visualize the left and right channels separately with a rainbow color scheme, use this configuration:

ffmpeg -i input.mp3 -filter_complex "[0:a]showspectrum=s=1280x720:mode=separate:color=rainbow:slide=flow[v]" -map "[v]" -map 0:a output.mp4