n8n Workflow: Merge Video Clips to MP4 with FFmpeg

Merge Multiple Video Clips into One MP4 (Automatically) with n8n + FFmpeg

This self-hosted n8n workflow takes two or more uploaded video clips, scales and pads them to your chosen output size (landscape, vertical, or square), and merges everything into a single MP4 using FFmpeg’s concat filter.

What this workflow does

• Receives a form submission with at least two video files plus a selected output size.
• Creates a per-run temporary folder and generates an ordered list of clip paths, along with the target width/height.
• Saves the uploaded clips to disk in the exact order the user selected them.
• Builds and runs an FFmpeg command that:
  • scales and pads each clip to the target frame,
  • normalizes video to 30 fps,
  • reformats audio to a common sample rate/layout,
  • then concatenates all clips into one MP4 using FFmpeg concat filter (not the concat demuxer).
• Fails safely: if the merge fails, the workflow stops with FFmpeg’s stderr output.
• Returns the merged MP4 plus a brief report including clip count and output dimensions.

Use cases

• Quickly combine multiple clips into one video for social media with consistent sizing.
• Batch-create compilation MP4s from user uploads in an internal tool.
• Standardize mixed source formats by forcing a uniform resolution and frame rate before publishing.

Technical details

• Self-hosted n8n required (uses the Execute Command node; does not run on n8n Cloud).
• FFmpeg installation on the same machine; ensure the ffmpeg binary is on the PATH for the n8n process.
• File access configured for /tmp (e.g., N8N_RESTRICT_FILE_ACCESS_TO="/tmp") so the workflow can write inputs and read the resulting MP4.
• Implemented with nodes: Code, Sticky Note, Form Trigger, Read/Write File, and Execute Command.