Re: [GnomeMeeting-list] [PATCH] QCIF Small (Scaled) capture mode

[bteague rice edu]

> Hello Brian,
> 
> Unfortunately, as I understand the patch, it only scales the picture
> when displaying it, not for transmission. 

Yes.  I noticed that.  I was so excited to finally have local video looking good
that I forgot to check the transmitted result.

> 
> If you are still interested in developing a patch to be able to make
> your driver capture in CIF, but to transmit a QCIF scaled down image, it
> has to be done in pwlib. It is of course very interesting to do because
> that way, cameras supporting QSIF (160x120), could scale up the image to
> QCIF (176x144) before sending the picture.

I think arbitrary scaling of the transmitted video (ie, from an arbitrary frame
size to CIF or QCIF) sounds like a good idea.  Unforunately, I was using
Gdk-pixbuf to do the actual scaling, which means I'd have to actually implement
the scaler myself.  Or does PWLib have it somewhere already?

> 
> Let me know if you are interested in doing this, and I will guide you
> through the code, it is very uncommon to find people willing to help.

Certainly.

At first, I tried doing it in videograbber.cpp, in the main loop between
channel->Read() and channel->Write().  The implementation was really clean, but
the results were horrible; apparently, H323VideoDevice::Redraw() does some
conditioning of the image that makes it scale better.  (Or is it just that the
image data between channel->Read() and channel->Write() isn't in RGB format yet,
and so a simple box filter doesn't work?  I couldn't really tell.)

I'd be more than happy to work on a more general-purpose version of this
concept... as long as it still works in the special case for which I attempted
to write it in the first place.  (-;

Thanks!

Brian