---
type: entity
title: FFmpeg
tags: [multimedia, command-line, video-processing]
related: [opencast-studio, grypstube]
created: 2026-06-30
updated: 2026-06-30
sources: ["output/rz_uni_greifswald_de_dienste_studium_lehre_elearning_vod_videoaufzeichnung.md"]
---

# FFmpeg

FFmpeg is a command-line multimedia framework used at the Universität Greifswald primarily for correcting technical errors in video files generated by [[opencast-studio]] to ensure they are compatible with the [[grypstube]] server.

## Use Case: Opencast Studio Correction
Files produced by Opencast Studio often lack essential runtime information and may have resolution issues that prevent immediate processing. FFmpeg is used to regenerate presentation timestamps (PTS) and ensure the video resolution is compatible (padding to even dimensions).

### Correction Commands
The URZ provides specific commands for different formats:

**For WEBM files:**
`ffmpeg -i inputfile.webm -c copy -fflags +genpts -vf pad="width=ceil(iw/2)*2:height=ceil(ih/2)*2" outputfile.webm`

**For MP4 files:**
`ffmpeg -err_detect ignore_err -i inputfile.mp4 -c copy -strict -2 -vf pad="width=ceil(iw/2)*2:height=ceil(ih/2)*2" outputfile.mp4`

## Implementation at URZ
For Windows users, the URZ provides a ZIP archive containing the FFmpeg binaries and a BAT file. This allows users to correct videos via a simple drag-and-drop interface, resulting in a file with the `_opt` extension.