Producing the videos of the gvSIG Conference


as we’ve done in the last years, the videos of the International gvSIG Conference were published at the Conference website one week ago.

The publishing of the videos takes several weeks because they have to be edited. That’s why we publish them later. I’m going to explain the steps we followed to publish them.

Every session usually has three or four presentations. We usually receive one DVD per session, and there are several VOB files in everyone. The first files have the same size (1GB), and the last one has the rest to complete the session. Sessions with simultaneous interpretation will have double audio, one for English and other for Spanish.

For editing videos, we used some video application, but we had problems with some videos. We finally used commands by console in Kubuntu and Ubuntu (installing ffmpeg and mencoder previously).

The first step is to join the .VOB files of a DVD, after copying them to our computer, to create an only .AVI file for the session. It can be done from the console, executing:

cat VTS_01_1.VOB VTS_01_2.VOB VTS_01_3.VOB VTS_01_4.VOB > completesession3.avi

After it, we have to separate the presentations of the session. For every presentation, we’ll execute from console:

ffmpeg -i [name_of_the_complete_session.avi] -t [duration_in_seconds] \
-ss [second_when_the_presentation_starts] -sameq [name_of_the_presentation.avi]

For example:

ffmpeg -i completesession3.avi -t 1095 -ss 1 -sameq session3_pres1.avi

When we have the AVI file of every presentation, we have to separate the Spanish and English audio, and convert it to FLV format (to decrease its size). We also do it from console:

  • For Spanish:
    mencoder [name_of_the_presentation.avi] \
    -o [name_of_the_presentation_Spanish.flv] -ovc lavc
    -lavcopts vcodec=flv:vbitrate=500:mbd=2:trell:v4mv:cbp:last_pred=3 \
    -oac mp3lame -af channels=2:2:0:1:0:0
  • For English:
    mencoder [name_of_the_presentation.avi] \
    -o [name_of_the_presentation_English.flv] -ovc lavc \
    -lavcopts vcodec=flv:vbitrate=500:mbd=2:trell:v4mv:cbp:last_pred=3 \
    -oac mp3lame -af channels=2:2:1:0:1:1

For example:
mencoder session3_pres1.avi -o session3_pres1_sp.flv -ovc lavc \
-lavcopts vcodec=flv:vbitrate=500:mbd=2:trell:v4mv:cbp:last_pred=3 \
-oac mp3lame -af channels=2:2:0:1:0:0

And that’s all, hope it helps for your next conference!!

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1 Response to Producing the videos of the gvSIG Conference

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