How to Use FFmpeg gblur Filter to Blur Video

This guide explains how to use the gblur (Gaussian blur) filter in FFmpeg to apply a smooth blur effect to your videos. You will learn the basic command syntax, the key parameters used to control the intensity and quality of the blur, and practical examples to help you integrate this filter into your video editing workflows.

The gblur filter in FFmpeg uses a Gaussian convolution cascade to blur the input video. It is highly efficient and offers precise control over the horizontal and vertical blur radius.

Basic Syntax and Parameters

The basic syntax for applying the gblur filter is:

ffmpeg -i input.mp4 -vf "gblur=sigma=10" output.mp4

To customize the blur effect, you can adjust the following parameters:

  • sigma: Sets the horizontal blur strength (standard deviation of the Gaussian formula). The default value is 0.5. Higher values result in a stronger blur.
  • steps: Specifies the number of times the filter is applied. More steps create a smoother, higher-quality blur but require more processing power. The default is 1.
  • sigmaV: Sets the vertical blur strength. If set to -1 (the default), it will automatically match the horizontal sigma value.
  • planes: Specifies which color planes to filter (YUV or RGB). By default, it filters all planes.

Practical Examples

1. Apply Uniform Blur To apply a moderate, even blur across the entire video, set a single sigma value:

ffmpeg -i input.mp4 -vf "gblur=sigma=20" output.mp4

2. Increase Blur Quality If the blur looks pixelated or has banding, increase the steps parameter to smooth out the transition:

ffmpeg -i input.mp4 -vf "gblur=sigma=30:steps=3" output.mp4

3. Apply Directional Blur To create a motion-blur effect horizontally while keeping vertical blur minimal, define different values for sigma and sigmaV:

ffmpeg -i input.mp4 -vf "gblur=sigma=30:sigmaV=2" output.mp4

Using these parameters, you can easily control the appearance and performance of the Gaussian blur effect on any video file using FFmpeg.