Information Theory, Pattern Recognition, and Neural Networks: Recordings



What follows is a description of the workflow used to record David MacKay's lecture series "Information Theory, Pattern Recognition, and Neural Networks".

To keep costs down, the video recording and editing was done entirely by volunteers. We made a few mistakes, and learnt a few things along the way. It is hoped that other research groups who wish to record their own lecture series on a shoestring budget can benefit from these tips and tricks. Be warned, however, that the process we arrived at is probably a bit of a Heath Robinson contraption. So if you have any professional recording experience, it will probably make you shudder.


The lectures made use of the blackboard as well as slides and dynamic content displayed using a projector. We wanted to make the lectures available for on-line streaming, preferably with synchronised slides, on or a similar site. So, we needed to

How long does it take?

It took more time to do the videos than we thought at first (it turns out there's a reason professional video recorders charge so much money). It took about 6-7 man hours to produce one hour of edited video footage and slides. You also need to make provision for 2-3 hours of waiting time for video format conversions and uploading videos.

Activity Hours People Total Hours
Equipment Check 1.0 1 1.0
Live Recording 1.0 3 3.0
Video Editing 0.5 1 0.5
Making Slides 1.0 1 1.0
Synchronising Slides 1.0 1 1.0


While making a video recording of a lecture seems a straightforward task, there are an endless number of things that can go wrong. As you'll likely be learning things as you go along, it's essential to do a realistic test run of your whole workflow so that you can iron out any kinks before recording a lecture series. For example, things we needed to work on were:

Miscellaneous Tips

Equipment and Software


The equipment you need will need to change depending on how many things you wish to record. We recorded a projector and the speaker. We used a digital mixer to switch between these videos on the fly. We could have recorded the videos separately, but that would likely have required additional work to synchronise the video sources during off-line editing. The same two to three volunteers attended to the following tasks during the live recordings: This is the list of hardware we used:

Tips when using a video mixer

Editing software

We experimented with a number of commercial editing offerings, e.g. Final Cut Pro and Adobe After Effects (After Effects is more for compositing and effects, and it's not designed for video editing, but we had it to hand, so we evaluated it as well). In the end, we found that for our simple needs, we could do all of the editing on the Linux platform using open source software only. In short, we used I've listed the APT command lines for installing the software on Ubuntu.


A library and command line tool for video editing. ffmpeg was used to:


An application for linear video editing.

OpenShot was used to do most of the video editing. It is a simple 'linear' editor, but we found that it better matched our requirements than leading commercial 'non-linear' editors:

If you need special effects or re-timing of footage, then it's best to buy commercial software and to do the time-consuming video compression conversions (think hours, not minutes). However, if you just want to splice snippets of video, audio and still images together, then OpenShot is great.

Some simple editing actions that were performed:

There are few things you need to watch out for when converting video formats:


An application for editing audio files.

The version of OpenShot we used did not let one visualise the audio timeline. So we used Audacity to look at the audio waveform instead. Audacity was used to quickly identify long periods of silence (e.g. when the audience works out a problem), to remove noise from the recorded audio (after extracting the sound using ffmpeg), and to amplify parts of the audio. After processing the sound, you can import it as a sound clip in OpenShot or replace the audio of the original recording via ffmpeg.

Image Magick

A library and set of command-line tools for image editing. Image Magick was used to process images related to the slides via bash scripting.


An application for image editing. Similar to Photoshop. We used GIMP to for editing images (e.g. slides and video inserts).

  Back to the videos.