[linux-audio-user] LAC Recording Guidelines

Joern Nettingsmeier nettings at folkwang-hochschule.de
Mon Mar 5 11:56:14 EST 2007


> ES> It would be nice with some recording guidelines for LAC. Both for
> ES> video and for audio.

well, for the speakers:

* it is not necessary that your slides be readable on our video stream - 
as marije pointed out, downloadable versions will be available. *but*: 
it would be helpful if your slides were visually distinct enough that 
video stream watchers can figure which slide is currently up (biggish 
headlines usually work well, and nobody has ever been dragged from stage 
for showing nice illustrations...)

* the video image would benefit greatly from dark-background slides - 
this would avoid the speaker getting drowned in darkness when the camera 
exposure corrects for the bright projection. (not a problem if we have 
stage lighting for the speaker, but that is unlikely.)

* if by luck stage lights are indeed available at and near the 
lecturer's desk - stay within their range :)

* use a traditional pointer or a large laser pointer. very small red
dots tend to get lost in low resolution and encoding artifacts...


we will try to have fixed camera positions this year or tune the codecs 
to avoid massive bandwidth surges.

regarding the combination of slides and audio/video, the mostest 
niftiest solution would be to have annodexed ogg streams, but this is 
not going to happen unless somebody volunteers as a full-time anodex 
editor during the conference and can set up the necessary toolchain 
him/herself. regrettably, my annodex knowledge is still limited to what 
conrad and silvia of csiro taught me 3 years ago at the LAC...


as to multiplexing:

the problem is that the toolchain we used last year 
(dvgrab|ffmeg2theora|oggfwd) relies on a dv stream with audio in it. 
that means that unless we get our hands on very professional camera 
equipment with external audio ins, the sound has to come from the 
build-in cam mike (the line ins of consumer-grade cams suck to the point 
of being completely unusable).

the only toolchain i'm aware of that allows for flexible muxing of audio 
on video after grabbing is flumotion, but i've had mixed results with 
that in terms of stability. if it can be made to work, that would be my 
preferred solution.

lastly, getting a good sound depends on whether we have the technical 
equipment and necessary cabling to tap into the conference mixers. 
should not be a problem, but has not been checked yet.



fwiw, i'll be dumping stream-related info at the lac wiki:
http://www.medienwissenschaft.hu-berlin.de/lawici/index.php/Live_Streaming


regards,

jörn



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