[Sumover-dev] Retrieving a user's video data

[Piers O'Hanlon]

Hi Thibault,

I'm not sure if you my previous email on this subject but here's some
more info: Basically you need to obtain the data after it has been
decompressed by the codec. The head_->video_data() data structure is
not used in VIC's normal operation (it is only used when lip sync is
in operation - It currently doesn't work properly). If you have a look
at  (I've just added a new section on the renderers):
http://frostie.cs.ucl.ac.uk/nets/mmedia/wiki/VicDev
You can see what the normal course of events is function by function
for receiving packets. As I mentioned I think the best approach would
be to copy one of the existing renders - then ensure that it is chosen
on start up by VIC (see my wiki page) or via some command line switch,
vic resource, or environment variable etc. This render could just
extract the video data and pass it to your tcl3d function.

For testing you could just modify the colour-scale.cpp renderer to
pass the video to the tcl3d function using tcl.evalc("your_3d_func"),
though I wouldn't recommend it for proper use as it will slow things
down.

Piers.



2008/11/17 Thibault Daoulas <thibault.daoulas at canterbury.ac.nz>:
> Hi,
>   I have a question about an issue I am quite stuck on for a while.
> Basically I want to render each video streaming of each participant, frame
> per frame, on an OpenGL texture. In order to do this, I want to get the
> video frames of each source, so ideally there would be a method in the
> rtp/Source class "getData()" which would return a u_char*, which I would
> then transfer to the tcl interface, and finally map as a bitmap onto an
> OpenGL (tcl3d in our case) texture.
> The point is that I do not really understand how to get this data. The
> method I thought adequate was "head_->video_data()", but each time I try to
> access it, I get a segmentation fault, and actually I do not know if the
> PacketData * head_ represents...
> Can anyone help me about this?
>
> Thank you very much for any advice,
>
> Thibault.
>
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