[vlc-devel] Filters in libvlc

jboileau jboileau at gmail.com
Thu Jun 19 14:52:52 CEST 2008

> libvlc_video_add_adjust() => maybe we should make function:
> libvlc_activate_video_filter(char *psz_filter)

That all depends if we want to keep in line with the libvlc API
design. Pierre d'Herbermont is the one that can guide us here. I too
thought of passing the filter as parameter as you suggest, but when I
looked at the libvlc API and it didn't feel in line with the design.
And I also wondered if we wanted the user of the API to have to know
about the string notation. I am also not in favor of an API that
relies on string which gets evaluated at runtime. I like to see my
errors at compile time. If you pass "adjusd" instead of "adjust" it
will compile but it won't work. If you type libvlc_video_add_ajusd it
simply won't compile. From my experience this is better and saves time
debugging. This is my own preference, but is debatable.

As for naming I thought of many pairs of keywords: add/remove,
create/destroy, enable/disable, activate/deactivate etc. I finally
used add/remove because filters are added and removed. They are not
there and then we activate them.

> Next point, some variables in filters are floats (brightness,

You're right, just didn't get to those functions in my testing yet. :-)

> I am not sure, but wouldnt it be better if we handle filters and
> options by some internal (static) functions in libvlc?

I don't understand what you mean, sorry. Could you elaborate.

> At this moment I would appreciate something for testing that, because
> So if you have some program for testing that, it would help
> me a lot.

I can test whatever API you can develop easily. But my environment is
Windows. I use cygwin to compile the VLC dll's and I have a Microsoft
C++ application that uses them. I must use GetProcAddress to get the
functions from the DLL's because there is no way I know of to get a
Microsoft compatible .lib for these DLLs. Long story short: my test
app is probably too complicated for you to use. But its free and
available if you want it. :-) Doing VLC dev under Windows is certainly
not the best, but the one I must use. And debbugging is even harder,
mostly only msg_Dbg is usefull. But testing myself for you might be a
better alternative. We'll see as we go along.

Jacques Boileau

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