Aufmt

Overview

Aufmt is a rule-based audio and video encoder. It can be used to transcode media into your preferred formats using ffmpeg as a backend. See the provided config/example.js for an example of how to configure your encoding rules.

Install it from NPM:

npm install -g aufmt

Usage

To see the provided documentation, use aufmt --help.

Inspecing files

You can use the aufmt command on its own to analyze a file and show the various sub-streams:

$ aufmt your_file.mkv
your_file.mkv:
* v:0 hevc jpn [default]
* a:0 ac3 eng fltp (6) [5.1(side)] [default]
* a:1 ac3 eng fltp (2) [stereo]
* a:2 ac3 jpn fltp (6) [5.1(side)]
* s:0 subrip eng [forced]
* s:1 subrip eng

Re-encoding files

Re-encode your media based on rules defined in the ~/.aufmt.js config file. See the config/example.js for an example of how this config file should be defined.

Basic Transcoding

It is recommended to use the -d option initially to perform a dry-run. This will display the stream transformations without performing any re-encoding:

$ aufmt recode -d your_file.mkv

When you are satisfied, remove the -d option to perform transcoding (if needed).

By default, aufmt will output the file using a temporary suffix. For example, the file your_file.mkv will be transcoded to a file following the pattern your_file.XXXXXX.tmp.mkv.

If you would like aufmt to replace the original file when transcoding is finished, use the -r option:

$ aufmt recode -r your_file.mkv`

Please use this carefully as it is destructive and can result in data loss.

Find more details using the aufmt recode --help command.

Stream mapping

By default, all streams will be copied or transcoded into the output file. You can select or deselect specific streams using the -m (map) option. For example:

$ aufmt recode your_file -m v:0,a:1,sn

This will select the first video stream (v:0), the second audio stream (a:0), and will de-select all subtitle streams (sn). This syntax is designed to mirror ffmpeg's -map option.

Reordering streams is not currently possible, please use a post-processing tool like mkvmerge if you need to manipulate streams in a more complex way.

Additional options

Additional options can be passed to the ffmpeg backend using a variety of ways:

• Presets: Use -p to specify a named rule preset to apply (defined in your config file), instead of using the default preset defined in the configuration file.
• Option Groups: Use -o to specify a named option group (defined in your config file) to be included with the ffmpeg command.
• Inline Options: Use -v, -a, and -s to specify additional video, audio, and subtitle encoder options inline, as needed.

When using complex transcoding configurations it is highly recommended to use the -d option for a dry-run to preview the ffmpeg options before performing a transcode.