Re: [GnomeMeeting-list] saving frames to file

[Damien Sandras <dsandras seconix com>]

Le mer 16/10/2002 à 23:32, Sam Wiebenson a écrit :
> In order to evaluate the video out of gnomemeeting across a constrained
> link (ie: 50 kbps) I would like to save every frame of video 30 sec. or
> so on both sides and compare (run it through Matlab and calculate PSNR
> or something to that effect).  After looking in the code for a bit I
> thought GDKVideoOutputDevice::Redraw might be the best place to stick in
> a call to gdk_pixbuf_savev, or something along those lines.
> 

Yes it is the right place.

> Is this a good way of going about this?  Is there a better way?  Will
> this adversely effect gnomemeeting by slowing it down with all these
> writes to the disk?  

Yes unfortunately, it will slow it down. The best to do is to queue the
frame and add another thread reading the frames and encoding them in
mpeg to finally compress and write them to the disk.
Writing raw data to the disk will require to write :
176 * 144 * 3 (RGB) = 76032 octets = 9.5kb to the disk for each frame.
It will thus slow things down.

> 
> Another problem with this is I would like to have some way to match up
> the frames on both sides besides just looking at them.  Does
> gnomemeeting have some sort of frame id number?  Is it in OpenH323
> instead?

I record a private variable, that is the frame number (frame_number I
think). You could use it in the filename.

> 
> Thanks for any help,
> -sam
> 
> 
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