1. Understanding the Delogo Filter

The delogo filter suppresses a rectangular logo or watermark by interpolating pixels from the immediate surroundings. Rather than applying a destructive Gaussian blur or pixelated mosaic filter, it samples the clean boundary pixels outside the target bounding box and computes an interior reconstruction using a discretized numerical solution of Laplace’s equation:

∇2 I = 0 ⇒ ∂2I / ∂x2 + ∂2I / ∂y2 = 0

By enforcing smooth second-order derivatives, the filter reconstructs color gradients across the removed area, rendering stationary bugs virtually invisible against natural backgrounds like skies, water, or textured surfaces.

2. Essential Parameters of the Delogo Filter

Parameter Type Default Description
x Integer None (Required) The horizontal offset in pixels of the top-left corner of the logo.
y Integer None (Required) The vertical offset in pixels of the top-left corner of the logo.
w Integer None (Required) The width of the logo rectangle in pixels.
h Integer None (Required) The height of the logo rectangle in pixels.
band / t Integer 4 The thickness of the border rectangle used for sampling surrounding pixels.
show Boolean 0 When set to 1, draws a green bounding box around the target region for alignment checks.

3. Step-by-Step Command Line Walkthrough

Step 1: Previewing the Coordinates with the Green Box

Never encode a full video blind. Use FFmpeg with show=1 and preview a single frame using ffplay or save a test frame:

ffplay -i input.mp4 -vf "delogo=x=1680:y=60:w=180:h=90:band=2:show=1"

Verify that the green outline fully envelops the watermark with at least 2 to 4 pixels of padding on all sides.

Step 2: Production Video Clean & Lossless Audio Passthrough

Once you have confirmed coordinates, run the production render. Always pass -c:a copy to prevent audio re-encoding:

ffmpeg -i input.mp4 -vf "delogo=x=1680:y=60:w=180:h=90:band=1:show=0" -c:v libx264 -crf 18 -preset fast -c:a copy output_clean.mp4

💡 Video Engineering Tip: The Band Parameter

Setting band=1 is ideal for sharp high-contrast logos where sampling closer to the boundary prevents edge halos. If the surrounding background has gradients (like sunset skies), setting band=4 softens transitions and blends more naturally.

4. Delogo vs Removelogo: What is the Difference?

While delogo accepts simple rectangular coordinate numbers (x, y, w, h), the removelogo filter operates on an arbitrary-shaped bitmap mask file:

  • Input format: removelogo takes a monochrome Portable BitMap (.pbm) or gray image where white pixels denote the exact shape of the logo to remove.
  • Complex shapes: Ideal for non-rectangular logos, cursive station signatures, or circular channel icons.
  • Syntax: ffmpeg -i input.mp4 -vf "removelogo=filename=mask.pbm" -c:a copy output.mp4.

5. Hardware Acceleration & NVENC Performance Benchmarks

Because spatial interpolation requires reading and synthesizing pixel values on every frame, high-bitrate 4K media benefits greatly from hardware acceleration:

Encoder Hardware 1080p 60fps Speed 4K 30fps Speed
libx264 (crf 18) AMD Ryzen 9 7950X 94 fps (1.5x realtime) 28 fps (0.9x realtime)
h264_nvenc NVIDIA RTX 4080 285 fps (4.7x realtime) 86 fps (2.8x realtime)
hevc_nvenc NVIDIA RTX 4080 240 fps (4.0x realtime) 74 fps (2.4x realtime)

Summary & Best Practices

  1. Always test boundary boxes first with show=1.
  2. Keep the selection box as small and tight as possible to minimize the interpolated surface area.
  3. Never re-encode audio: use -c:a copy to preserve original fidelity.
  4. For fast web-based spatial delogo without installing command-line tools, use our hardware-accelerated Online Video Studio.