[vlc-devel] [PATCH] Vovoid VSXu audio visualization integration

[Jonatan Wallmander]

Added visualization plugin using Vovoid VSXu - real time graphics 
modular programming language
http://www.vsxu.com

Since VSXu isn't packaged into any binary Linux distributions yet, to 
build it you need to build it yourself (for windows also obviously).

For simplicity - use VSXu's build scripts:

https://github.com/vovoid/vsxu-build

(put this in ~/vsxu/build )

And the actual source code of VSXu (use master branch):

https://github.com/vovoid/vsxu

(put into ~/vsxu/vsxu )

Then go:
cd ~/vsxu/build
cd linux64   (or linux32)
./prepare  (if you actually want to install, use ./prepare_usr)
cd build
make -j4
make install
export LD_LIBRARY_PATH=/home/$USER/vsxu/build/linux64/install/lib/
export PKG_CONFIG_PATH=/home/$USER/vsxu/build/linux64/install/lib/pkgconfig

(there are also build scripts/examples for win32/win64 for compilation 
with mingw-w64)

Then VLC should find it and compile happily.


Some general comments about the implementation/integration:

To accomplish this, I wrote a cyclic buffer class for interim storage of 
audio fragments as I found out that the Project M implementation (which 
I forked) receives audio  0.3-0.4 seconds out of sync (ahead of time; 
may vary for you), using PTS values sent via block_t.i_pts. 
Synchronization really makes or breaks a music visual. If you want to 
test audio sync with visuals, use this file:

https://github.com/vovoid/vsxu/blob/master/tests/audio/latency_test.mp3     
(series of 880Hz beeps)

If there's a better (VLC) way to do this, I should do/use that instead.
The code is also doing some tricks to keep VSXu getting at least 60 
Hz/FPS (512 sample blocks) of audio data so that the visualization is as 
exact and dynamic as possible (the concept is: vsxu must have new audio 
data every frame, VLC doesn't call its audio filter callback that often).

If and before incorporating this into any vlc package of any kind we 
need to go through which visual effects (design-wise) are suitable, this 
is out of scope for this commit. This patch thus just adds the code, so 
take it for what it is. Feel free to botanize among the visuals 
currently in the
vsxu repository, some are quite large and slow to load so those have to 
be axed and shipped separately (perhaps as downloadable from our site) 
for instance.

/jaw
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