ffmpeg Scripts

Bash scripts to help automate common ffmpeg video-conversion commands that I'm always using for work!

---

Prerequisites

1. A Linux-like environment with a bash version that supports the read command:
   • read is a bash builtin that may not exist in older versions of bash — check by running: help read or man read
2. A working ffmpeg installation with the necessary libraries for MP4, OGV, & WEBM formats:
   • I use Homebrew to install ffmpeg — the latest homebrew installation and info can be found at: https://brew.sh/:
     • Once brew is working install ffmpeg and libraries using: brew install ffmpeg --with-fdk-aac --with-libass --with-libvpx --with-openssl
   • OTHERWISE, ffmpeg can now be installed as a standalone software/tool: https://ffmpeg.org/download.html

Check out more information about ffmpeg at the official website: https://ffmpeg.org.

---

Checking your ffmpeg installation

This section is provided as a convenience and is not necessary — especially if you have a brand new ffmpeg install of the latest version. The scripts in this section are used to verify your ffmpeg installation and configuration settings.

If you installed ffmpeg a long time ago, you may want to run these scripts and make sure your install can handle the video conversions.

ffmpeg version

Use the bash script ./scripts/ffmpeg-version.sh to figure out what version of ffmpeg you are using:

sh ./scripts/ffmpeg-version.sh

It uses the output from running ffmpeg -version to get your version number.

At the time of writing this, I am using ffmpeg version 4.4 which is not the latest (version 5.)

Enabled libraries

Run this command to make sure you have the libtheora, libvorbis, libvpx, & libopus libraries installed and enabled in ffmpeg:

sh ./scripts/ffmpeg-enabled-libraries.sh

It checks for each of the libraries in your ffmpeg configuration and will let you know if any are missing.

It uses the output from the ffmpeg -buildconf command to check for the correct --enable-lib* settings.

---

Usage

1. Copy your source *.mp4 video-file into the local ./scripts/IN/ folder
2. Run desired bash script:
   • E.g. sh ./scripts/mp4-to-ogv.sh
3. Answer any prompts (to set your quality settings,) or press return to accept defaults.
4. The converted video will be output to the local ./scripts/OUT/ folder after ffmpeg has completed running (which may take several minutes depending on file size.)

---

The Scripts

This repository contains the following bash scripts in the (./scripts/ folder):

  ./scripts/
      |---- ffmpeg-enabled-libraries.sh
      |---- ffmpeg-version.sh
      |---- mp4-to-ogv.sh
      |---- mp4-to-webm.sh
      |
      |---- IN/
      |      |____ *.mp4              ## Source MP4 files here ##
      |
      |____ OUT/
             |____ *.{ogv,webm,mp4}   ## Converted video files here ##

Check your ffmpeg install/config

• ffmpeg-version.sh — bash script to verify ffmpeg is installed and return ffmpeg version number
• ffmpeg-enabled-libraries.sh — bash script to check if libtheora, libvorbis, libvpx, & libopus are installed and enabled in ffmpeg. These libraries are necessary to run most of the ffmpeg scripts in the project.

Convert videos

Script	Description	Features	File Naming
mp4-to-ogv.sh	bash script to convert MP4 file into OGV format	Video & audio quality are set when prompted	<SOURCE_FILENAME>_v<#>-a<#>.ogv — where <#> represents an integer corresponding to the chosen video and audio quality settings
mp4-to-webm.sh	bash script to convert MP4 file into WEBM	Video & audio quality are set when prompted	<SOURCE_FILENAME>_crf<#>-a<#>.webm — where <#> represents the video and audio quality settings

MP4 to OGV — mp4-to-ogv.sh

Use this script to convert an MP4 video file into OGV.

It uses libtheora and libvorbis to convert the audio and video streams from your source MP4 file.

Default video and audio settings are as follows:

• Video quality: 6
• Audio quality: 3

Press return when prompted for video and quality settings to accept the default values. If these quality settings produce a video file that is too large, reduce the quality settings and run the command again.

MP4 to WEBM — mp4-to-webm.sh

Use this script to convert an MP4 video file to WEBM.

It uses libvpx-vp9 and libopus to convert the audio and video streams.

• Video quality is set using the -crf flag (default is set to 30.)
• Audio quality is set using the -b:a flag (value should be specified as a bitrate e.g. 128k — which is the set default.)

---