transcode #1

Supports: precise
Add to new model


Video transcoding is a complicated, resource intensive options.
This charm breaks a video into N chunks, and farms out video transcoding
to N workers. It can take video files of many different types. The output
will always be a web-viewable .mp4, using h264 and aac codecs.


This charm will transcode videos of basically any format and codec, to an HTML5-compatible mp4 file, using the h264 video codec, and the aac audio codec.


  • Install

juju deploy nfs
juju deploy -n 4 transcode
juju add-relation nfs transcode

  • Copy a video file into any node's /srv/ directory

  • The results will be in the /srv/ directory, with a file ending in .mp4

  • You can watch the progress, view, and download the output by pointing a web browser at any node

Scale out Usage

The performance of the transcoding will scale linearly, with the number of transcode units. For instance, a video that takes 10 minutes to transcode with a single node, will transcode in 1 minute with 10 nodes.

juju add-unit -n 10 transcode


  • Update the input_url and/or output_size configuration variables

juju set transcode input_url=/srv/foo.avi output_size=copy
juju set transcode input_url=
juju set transcode input_url= output_size=960x540
juju set transcode input_url= output_size=640x360

Known Limitations and Issues

This charm currently supports transcoding most formats to mp4/h264/aac, and scaling the video to a different size. There are a few non-free formats (e.g. divx) which are not easily supported on Linux.

Video's served over HTTPS will cause an arbitrary error at present.

With the Transcoder leveraging NFS - this charm is not suitable for the Local provider / LXC containers.

Contact Information

This charm was written by Dustin Kirkland, and uses libav for transcoding.

Upstream Project Name


(string) input file; path to local file in /srv, or remote URL to fetch
(string) output frame size, see avconv(1)