[clug] Video interleaved with slides

Michael Still mikal at stillhq.com
Sat Feb 5 00:33:13 MST 2011

On 2/5/11 5:52 PM, Anthony David wrote:
> Hi All
> I was impressed with the videos of LCA 2011 where it looks like the slides were inserted into the videostream.
> Does anyone know the tool(s) used to do that?

Did you see the reply to you on the LCA chat list which answered this? 
To quote that cause I'm lazy:

"Hi Anthony,
It was done using a vga capture device called a twinpact100 which 
captured the vga output and gave us a firewire dv stream 
(http://en.wikipedia.org/wiki/DV) This stream was then combined on the 
fly with the dv stream from the video cameras that was filming the speaker.

We used a program call dvswitch 
(http://dvswitch.alioth.debian.org/wiki/) to switch between the two dv 
stream sources and to provide a number of sinks. One of the sinks was 
the live ogg stream that people could view via a link to our website 
(html5), a file sink for later editing and a possible third plain dv 
stream that was used in the overflow room where we wanted a higher 
quality image.

The fantastic volunteer camera operators were the ones that did the 
switching and the pic in pic stuff. The pic in pic was where one video 
stream was contained in a little window within the other one.

At the end of recording what we got from dvswitch was a number of files 
that had a timestamp, date a room number. These files were created by 
the camera operators by pressing cut in Dvswitch which created a new 
file which had a timestamp on it. The operators might press cut from the 
start of the talk to question time and from then to the end of question 
time. They might also create a number of false start files. We then used 
a program called Veyepar to chop/combine files into a full talk.

Veyepar has been created by Carl Karsten who we had at the conference 
and who did most of the editing for lca2011. Ben Hutchings who is a main 
developer of Dvswitch was also at the conference and helped out getting 
the streaming servers. We also had a lot of help from Ryan Verner who 
has recorded a few conferences using this same platform (OSDC 2010, 
Pycon.au 2010 and 2009) he helped out with the scripts used to control 
Dvswitch and did the html5 for the video streaming.

I would strongly recommend the way we did this to other conferences. 
Dvswitch is quite flexible and versatile. Veyepar while a pain to setup 
(thanks Carl) is quite easy to use and saves a lot of time and effort 
when it comes down to editing a conference full of videos.

The really big thing is if you do intend to stream then you do need a 
good enough network to handled it. Otherwise you can just save the 
streams to the local pc and from there copy them over to your main 
storage at night where you also do the editing and transocding.

We also had heaps of help from QUT AV services. They were fantastic. We 
couldn't have done what we did without their help. I would also stress 
that the help of the volunteers was also a key ingredient. Both the AV 
volunteers and the ushers who without their help we would be spending a 
heck of a lot longer editing video. A big thank you goes out to them. 
There were some that we had to keep our eye on (Tony ;-) ) but they all 
did a very impressive job (Tony included).

Matthew Franklin (AV team)"


More information about the linux mailing list