Category Archives: LCA

All LCA video online

Digital Media, LCA

I’ve just fixed some missing links on the LCA video site, so all the talks are now online – yay!

It’s been an interesting experience, which is still not finished. I’m working on collecting all the slides for the talks and putting them into a common format (probably both pdf and odf). Jean-Marc is still working on transcoding the videos to speex (speech-only). And then there are all the annotations that we received through the irc channel, which I’d like to publish onto a cmmlwiki together with the videos.

It will all come in good time. The hardest and most important task were the videos.

I think we found a good formula this year to make the videos happen. DV tapes are impossible to handle. Recording to DVD provides a good backup straight away and a simple storage means. It could be further simplified if recording was done straight to disk and everything handled as files only, which is the way in which the DebConfs were done. But then – I am a big fan of having physical, high-quality backups.

Here’s a little FAQ for those annoying recurring questions:

  1. Why are there not all miniconf talks present?
    We did not aim to record Monday and Tuesday, but rather used them as testing days for the equipment and the team. Therefore, having any video at all from the miniconfs is a bonys.
  2. The sound is rather quiet on some videos – can you fix that?
    Unfortunately, some days came out really quiet and it will take a lot of post-processing to fix this. We don’t have the time and people to undertake this. So, just turn up your speakers, the volume on your desktop and on the application.
  3. What software did you use to transcode and publish?
    We are only publishing the video in the open and free Ogg Theora format. Since we recorded straight to DVD, all we had to do thus was to rip the DVDs using "vobcopy" (with the “-l” option in order to get all the pieces on the DVD stiched together). If the resulting vob file consisted of multiple sessions, then the timing restarted in the middle which confuses transcoding. So, we used "avidemux" to recreate a correct MPEG_TS (transport stream). The resulting vob file was transcoded to Ogg Theora using a ffmpeg2theora script and finally uploaded to the server using "scp" with the “-l” option. On a fast machine and a fast connection, each of these steps is faster than realtime (i.e. takes less time than the duration of the video). My slowest process was the upload, which I had to do over night in batch from my home ADSL connection.
  4. How much space do the published Ogg Theora files use?
    Using the “-p preview” option of ffmpeg2theora provides you with 384×288 video at 25 fps for PAL recordings. The size in bytes varies a lot between the files. Our largest file is about 257MB and is from a 1:23 hrs long talk. Our shortest file is about 10MB and is from a 6 min long talk. Overall we’re using 11.9GB of disk space for 141 files. That comprises only the Ogg Theora video files. The vob files are a bit more than 10 times the size of a Ogg Theora file, so we don’t keep them on the server.

Funny little game

LCA

At LCA, two journalists came and played this little game of “sucks and scores” – you were given a keyword and had to quickly reply with “sucks” or “scores. They joined us at one of our video team meetings – and the result is here. Turned out quite funny IMHO – though it’s of course totally unbiased by the fact that it was played at LCA!

LCA Video Team

Digital Media, LCA, Open Source

I keep getting asked how we did the technical setup, so let me share it here.

With Video at LCA, this year, we did not want a repetition of the more experimental setups of previous years. We set out with only one goal: to publish good quality video during LCA to increase the number of talks that people will be able to look at and discuss. Our only aim is the Ogg Theora format since it is the only open video codec and what would a conference on FLOSS be if we didn’t stick to our ideals even with codecs!

One consequence of our narrow goal is that you will not find any live video streaming at LCA in 2007. The reasoning behind this is that we reach maybe a few hundred people with streaming, but that publishing reaches millions. Another reason is that previous years of video recordings at LCA have mostly had problems with one particular part in this picture: computers. So, we decided to take the computer out of the recording process and only use it in the transcoding, uploading and publishing part of the conference.

We are therefore recording from the DV cameras straight to DVD, which provides us with a physical backup as well as a quick way to get the data into the computer (in comparison to using DV tapes). Though this means that we use a non-free compression format in the middle of our process, it makes it a lot less error-prone. We’re waiting for the day when we can replace our camera – DVD recorder setup with Ogg Theora recording hard-disk cameras!

But the technical part of the video recordings is only one part of the picture. If you want good quality footage, you have to put people behind the cameras at all times. Speakers do weird things and a recording of slides with voice-over is not a very sensible video recording of conference talks. You really require a minimum of 2 people per lecture hall to cover the semi-professional setup that was required for the Mathews theatres: one looking after the audio and the other after the video, with a bit of slack time to give each other a break.

In parallel to the camera crews, we have a transcoding and upload team, which constantly receives the DVDs (and the DV tape backups) from the recording rooms. You also need stand-by people for relief. The upload process involves editing of the start and end points of videos, then a transcode to Ogg Theora and an upload to a local file server at the conference. This video gets mirrored to a Linux Australia Server and published into the conference Wiki through an automatic script.

We are very lucky to have a competent and reliable A/V team of volunteers at LCA 2007 who give up their opportunities to attend the conference for the greater good of all of us. Each team member covers all the days and it takes a lot of dedication to be up in the morning before everyone else (and possible after a hard night’s partying) and working a full day behind the camera or the computer. One of the team members even spent his birthday behind the camera!

I’d like to thank everyone on the A/V Team (in no particular order):

  • Timothy Terriberry,
  • James Courtier-Dutton,
  • Michael Dale,
  • Holger Levsen,
  • Nick Seow,
  • Sridhar Dhanapalan,
  • Chris Deigan,
  • Jeremy Apthorp,
  • Andrew Sinclair,
  • Andreas Fischer,
  • Adam Nelson,
  • Ryan Vernon, and
  • Ken Wilson.

In addition, the networking people have worked hard to make the uploading and publishing process as smooth as possible – I’d like to thank in particular John Ferlito and Matt Moor for their hard work.

It was a great experience to work with such a large team in such a professional setup where we managed to overcome many technical and human challenges and get the first video published even during LCA!