Meeting Minutes of 21.7.2004

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1. Intruduction

The meeting took place on June 21, 2004, at 14:00 CET. The following
people were present:

~   Martin Bayer
~   Georg Seidel
~   Philipp Promesberger

2. GUI for 0.5

The main focus of our first gui for 0.5 should be on the use as a live
vj tool. A concept with similarities to audio mixers with channels,
busses was discussed.

The requisites for a prototype are a video input and a output server, a
scheme scriptable gephex core that replaces konsolenphex. It was decided
to delay the gui issues till then.

2. Scheme

Scheme[4] will be the language for interfacing the c++ gephex core. The
core is a library. And its functions are exported to a scheme environment.

An open issue is the appropriate scheme interpreter for us. The options
guile[1] and mzscheme[2] will be evaluated by Georg. The usefullness of
~ swig[3] as ffi compiler should be checked.

The next step is to import all core functions in the scheme world and
reemplement the konsolenphex in scheme.

3. ffmpeg

ffmpeg[5] will be used for videofile decoding and will replace
libavifile[6] in the long run.

The steps to use ffmpeg in gephex are:
- - import the current cvs version of ffmpeg into an arch repository and
provide a possibility to import the cvs changes. The name for the ffmpeg
arch should be ffmpeg--cvs--0.35. cscvs[7] seems to be a tool that
achieves that
- - use configs[8] to include the ffmpeg sources in the gephex sources at
contrib/ffmpeg
- - update the build system of gephex 0.4 to configure and build the
ffmpeg subtree
- - write a frboutput driver for gephex 0.4 that uses ffmpeg

Phillipp will look at these issues.

4. IO Server

In 0.5 there will be extra processes called servers for i/o. These will
replace all i/o units in 0.4. E.g. the videofile decoding will be moved
~ into a videoinput server. The gephex core requests frames from the
server, the server decodes the frames and sends them to the core.

We have started to design the lowlevel api for the ipc protocoll and
discusses several technical issues. Martin will send a summary of the
design decisions regarding this to the list and will implement a prototype.


[1] http://www.gnu.org/software/guile/guile.html
[2] http://www.plt-scheme.org/software/mzscheme/
[3] http://www.swig.org/
[4] http://www.swiss.ai.mit.edu/projects/scheme/

[5] http://ffmpeg.sourceforge.net/
[6] http://avifile.sourceforge.net/
[7] http://wiki.gnuarch.org/moin.cgi/cscvs
[8] http://www.flibuste.net/libre/tlarefexport/texinfo/tla_9.html#SEC80

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