Talk Video Procedure

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Contents

About

This is Stefano Rivera's procedure for archive CLUG talk video. It's still under flux, I just don't want to forget it...

At the Talk

  • Manual white balance, if possible.
  • Mount the camera on a tripod, on one of the back desks. Zoom it in, to cut out everything except speaker and screen. Preferably not too many lit areas on the side, or auto-exposure goes out.
  • Light the speaker if possible.
  • Turn down the audience lights if possible.
  • Mount a microphone on or near the speaker if possible.
    • I've used my iRiver MP3 recorder, with a shirt-clip condenser mic, and AGC. The audio is out of sync, but can be rectified in audacity. Record a loud clap at each end to help sync.

Capture

dvgrab --autosplit --opendml --size 0 --format dv2 --duration HH:MM:SS talk-

Delete the irrelevant files. Rename the relevant one to talk-dv.avi

If there is more than one, join them: 

mencoder talk-00[4-9].avi -ovc copy -oac copy -o talk-dv.avi

Create Title

Templates:

Export as 720x576 PNG.

Encode with: 

mencoder mf://talk-title.png -mf fps=0.2 -ofps 25 -vf filmdint=io=1:100,harddup \
 -ovc lavc -lavcopts vcodec=dvvideo -o talk-title.avi

Shortcut script

See Talk Video Procedure/Script

Filter

Makes it more compressible, and de-interlaces: 

mencoder talk-dv.avi -vf pp=fd,denoise3d -ovc lavc -lavcopts vcodec=dvvideo -oac copy \
 -o talk-dv-filtered.avi -ffourcc dvsd

Encode audio

mplayer talk-dv.avi -vc dummy -vo dummy -af resample=44100:0:1 -ao pcm:fast:file=talk.wav

Edit if necessary, normal edits:

  • Noise removal (tweak the removal level if necessary - 20dB works well)
  • Compress (at ~20dB)
  • Change project rate to 44100
  • Export as talk-audio.wav 
oggenc -q -1 talk-audio.wav -o talk-low-vorbis.ogg
oggenc -q 1 talk-audio.wav -o talk-high-vorbis.ogg

Encode video

ffmpeg2theora -v 2 --optimize -x 320 -y 240 -K 256 --nosound \
 talk-dv-filtered.avi -o talk-low-theora.ogg

ffmpeg2theora -v 2 --optimize -K 256 --nosound \
 talk-dv-filtered.avi -o talk-medium-theora.ogg

ffmpeg2theora -v 4 --optimize -K 256 --nosound \
 talk-dv-filtered.avi -o talk-high-theora.ogg

Merge

oggzmerge talk-low-theora.ogg talk-low-vorbis.ogg -o talk-low.ogg
oggzmerge talk-medium-theora.ogg talk-low-vorbis.ogg -o talk-medium.ogg
oggzmerge talk-high-theora.ogg talk-high-vorbis.ogg -o talk-high.ogg

Archival copy

Contains un-edited audio + edited audio + un-filtered video. We need to use h264, because Theora doesn't support interlaced video. Should fit on a DVD. 

mencoder -nosound talk-dv.avi -ovc x264 -x264encopts interlaced:bitrate=5000 -o talk-archive-h264.avi
oggenc -q 5 talk-edited-audio.wav -o talk-archive-edited-vorbis.ogg
oggenc -q 5 talk.wav -o talk-archive-vorbis.ogg
ogmmerge -c "ARTIST=Foo Bar#TITLE=Baz#DATE=1 January 1970#LOCATION=CLUG Talk at UCT" -A talk-archive-h264.avi \
 -c "LANGUAGE=English: Original" talk-archive-vorbis.ogg -c "LANGUAGE=English: Edited" talk-archive-edited-vorbis.ogg \
 -o talk-archive.ogg
Retrieved from "http://wiki.clug.org.za/wiki/Talk_Video_Procedure"