media tools (was Re: [AG-TECH] AccessGrid 3: What information is available)

Rhys Hawkins Rhys.Hawkins at
Wed May 25 18:23:04 CDT 2005

I don't advocate the approach of throwing everything away and starting
from scratch, rather, work out what we want and then determine the bits
we can reuse, and I believe there is a lot in VIC/RAT that could/should
be reused. I gave libcommon as an example before but there is more.

I'm going to try and avoid language wars as best as possible, but I
need a starting point to explain what I would like to happen. I believe
that the lower levels should be C, my reasons are:
 - libcommon is C and it works
 - most free/OS codecs are in C/C++
 - capturing interfaces are in C
 - better access to platform specific services for performance (eg
Quicktime on Mac, DirectShow in win)
Someone will argue that you can wrap these things into another language,
but I think that wrapping should happen at a higher level. 

So what I would like to see developed is a C library(ies) of rtp et al,
capture interfaces, codecs. This can then be wrapped into whatever
higher level language you want. For the AG this would probably be
python, with the GUI in wxPython. In terms of the VIC code, this could
be achieved by ripping out the TCL/TK stuff from the codecs in VIC, ie
so the decoders no longer derive from TclObject and modify the
interfaces as appropriate. How feasible is this?

The benefit of this is that anybody could use this library, wrap it in
another language if they so desire(python, java, tcl/tk) and write their
own consumer or producer app and *know* that they will be compatible
with other video applications used in the AG. And if we have a common
stable base, then we might finally get away from H.261 only AG sessions!

I think this discussion is important as the video tool is vital to 
the long term success of the AG. 

Note, I've cc'ed this to the ag-dev list as this conversation should
probably move there.


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