visp is a minimal command-line wrapper around ffmpeg, written in Common Lisp for both educational and practical use.
It simplifies repetitive ffmpeg operations like resolution conversion, audio stripping, codec switching, and more — all while auto-generating output filenames.

Originally created as a Lisp learning project, visp has grown into a practical tool that automates and streamlines common video encoding tasks.

# Downscale a 4K video to 1080p and remove audio
visp --input sample_4k.mp4 --res fhd --mute

# Specify resolution explicitly with width and height
visp --input clip.mp4 --res 1280x720

# Transcode to HAP codec, preserving resolution and audio
visp --input sample.mov --codec hap

# Preview the ffmpeg command without running it
visp --input sample.mov --res 2k --codec prores --dry-run

# Downscale the input video to half its original resolution
visp --input demo.mp4 --half

# Reverse the video (mute implied)
visp --input intro.mov --reverse

# Repeat input video 4 times (original + 3 loops)
visp --input loopclip.mp4 --loop 3

# Change playback speed to 2x
visp --input sample.mp4 --speed 2.0

# Change playback speed to half (0.5x)
visp --input sample.mp4 --speed 0.5

# Flip video horizontally (left-right mirror)
visp --input sample.mp4 --hflip

# Flip video vertically (upside-down)
visp --input sample.mp4 --vflip

# Apply multiple options together
visp --input raw.mp4 --res hd --codec h265 --fps 24 --mute

# Specify custom output filename
visp --input source.mp4 --res fhd --output final_video.mp4

# Merge multiple mp4 videos into one
visp --merge intro.mp4 scene.mp4 outro.mp4

# Merge videos with custom output filename
visp --merge intro.mp4 scene.mp4 outro.mp4 --output compilation.mp4

# Convert a video to an animated GIF (fixed size, half fps)
visp --gif teaser.mp4

# Convert to GIF with custom output filename
visp --gif teaser.mp4 --output animation.gif

# Apply the same options to all videos in a directory (batch processing)
visp --input videos/ --mono --fps 24

Output filenames are automatically determined based on options.

Examples:

• sample_fhd.mp4
• sample_720p_30fps_noSound.mov
• intro_noSound_Reverse.mp4
• loopclip_x4.mp4
• demo_Half.mp4
• sample_2xSpeed.mp4
• sample_0.5xSpeed.mp4
• sample_HFlip.mp4
• sample_VFlip.mp4
• teaser.gif

Note:
If a directory is specified with --input, all video files in the directory will be processed in batch. The generated output files will be saved in the same directory as each input file.

You can also use visp to merge multiple .mp4 videos into one.

visp --merge part1.mp4 part2.mp4 part3.mp4

Requirements:

• All input files must be .mp4.
• At least two files are required.
• Files must either all have audio, or all be silent (no mix).
• All videos will be normalized to the resolution and framerate of the first file.
• The output file will be named after the first file with _merged.mp4 appended, or use --output to specify a custom filename.
• --dry-run and --output may be combined to preview the command or customize the output filename.

Example:

visp --merge clipA.mp4 clipB.mp4 --dry-run

Sample output:

[WARN] Detected different resolutions across files. All will be scaled to 1920x1080.
[WARN] Detected different fps values. All will be converted to 60.0fps.
[INFO] Planned output file: clipA_merged.mp4
[DRY-RUN] Command: ffmpeg -i clipA.mp4 -i clipB.mp4 -filter_complex "[0:v:0]scale=1920:1080,fps=60[v0];[1:v:0]scale=1920:1080,fps=60[v1];[0:a:0][1:a:0]concat=n=2:v=1:a=1[outv][outa]" -map "[outv]" -map "[outa]" -c:v libx264 -c:a aac -y clipA_merged.mp4

You can convert a single video file into an animated GIF using visp.

visp --gif input.mp4

Details:

• Only one input file is allowed.
• The output resolution is fixed to 640 pixels wide, height is auto-scaled to preserve aspect ratio.
• The output framerate is set to half of the original video’s fps.
• The output file will be named after the input with .gif as the extension, or use --output to specify a custom filename.
• Other options (e.g. --mute, --res, etc.) cannot be combined with --gif, except --output and --dry-run.
• --dry-run may be used to preview the ffmpeg command.
• A high-quality palette is generated with palettegen, and dithering is applied using dither=bayer:bayer_scale=3:diff_mode=rectangle for optimal compression and visual fidelity.

Example:

visp --gif teaser.mp4 --dry-run

Sample output:

[INFO] Planned output file: teaser.gif
[DRY-RUN] Command: ffmpeg -i teaser.mp4 -filter_complex [0:v] fps=15.00,scale=640:-1,split [a][b];[a] palettegen=stats_mode=single [p];[b][p] paletteuse=dither=bayer:bayer_scale=3:diff_mode=rectangle:new=1 -y teaser.gif

The easiest way to install visp is now via Homebrew! 🍻

Note: visp currently supports Apple Silicon (arm64) Macs only.

Step 1. Tap the repository:

brew tap ogrew/visp

Step 2. Install visp:

brew install visp

Step 3. Verify installation:

visp --help

That's it! Now you can use visp from anywhere.

If you prefer building manually or are not using Homebrew, you can build visp from source.

Requires Roswell and SBCL.

git clone https://github.com/ogrew/visp.git
cd visp
ros build visp.ros

Move the generated binary into a directory included in your $PATH (e.g., /usr/local/bin):

sudo mv visp /usr/local/bin/
sudo chmod +x /usr/local/bin/visp

Then you can use it like this:

visp --help

Planned features and improvements for future versions of visp:

• 🖼 Image sequence to video: Support for turning numbered images (e.g., %04d.png) into a single video.
• 🧩 Multi-input tiling: Combine up to 4 videos into a 2×2 tiled layout.

ffmpeg must be installed and available in your system PATH.

To confirm:

which ffmpeg
# /opt/homebrew/bin/ffmpeg

ffmpeg -version
# ffmpeg version 7.1.1 ...

If ffmpeg is not detected, visp will show an error and terminate early.

Developer environment used:

$ ffmpeg -version
ffmpeg version 7.1.1 Copyright (c) 2000-2025 the FFmpeg developers
built with Apple clang version 16.0.0 (clang-1600.0.26.6)

MIT License