[PD-dev] gavl and gmerlin-avdecoder in Fink and on build machines

[Hans-Christoph Steiner]

On May 5, 2009, at 4:02 AM, IOhannes m zmoelnig wrote:

> hi.
>
> sorry for the overcryptic mail...
>
>
> Hans-Christoph Steiner wrote:
>>>> working on getting readanysf~ compiling nicely.  Now that leads  
>>>> me to wonder: how about getting Gem on Mac OS X to use gavl and  
>>>> gmerlin-avdecoder?  I think it'll have much better codec support  
>>>> than Quicktime.
>>>
>>> how not to?
>> I don't understand.
>
> Gem uses configure to detect which libraries are available on the  
> build system. at least it does so on the autobuild machines.
>
> since the configury is usually greedy, it will take conscious effort  
> to disable a certain feature (e.g. the use of gavl/gmerlin once it  
> is detected)
>
>
>>> which complications do you expect?
>
>
> of course the above is not entirely true (there are a few hacks in  
> the configury to avoid groups of libraries which are known to cause  
> problems: e.g. ImageMagick will automatically disable libtiff).
>
> there might as well be special hacks that disable the use of the   
> more modular "new" (though quite aged by now) approach of film- 
> loading.
>
> i know that there _are_ such special hacks, i just don't know  
> whether they effect the film-business (without looking at the code)

For Pd-extended, we should not rely on automatic detection, since it  
is really a packaging question.  When packaging, the standard practice  
from what I've seen is to disable all automatic detection and  
explicitly tell configure what it should be finding.  For example,  
this is what we did in the Fink package for  gmerlin-decoder:

./configure --prefix=/sw --disable-gmerlin --enable-libavcodec -- 
enable-libpostproc --enable-libswscale --enable-libavformat --enable- 
theora --enable-speex --disable-mjpegtools --enable-vorbis --disable- 
libmpeg2 --enable-libtiff --enable-openjpeg --disable-samba --enable- 
libpng --enable-faad2 --enable-dvdread --enable-flac --enable-musepack  
--enable-mad --enable-liba52 --enable-libdca --enable-libcdio -- 
disable-win32 --with-avcodec=%p --with-avformat=%p --with-vorbis=%p -- 
with-faad2-prefix=%p

So ffmpeg, gavl, and gmerlin-decoder are now installed on all the Mac  
OS X build machines, so I think it would be good to give a similar  
treatment to the Gem options for Mac. Any suggestions?  You could just  
commit them directly, its in packages/Makefile.

>> Hmm, I don't really know enough to say.  August and I have been  
>> working quite a bit on getting this whole thing building in Fink  
>> and now MinGW.  I think then Gem, Gridflow, PDP, etc. can all use  
>> this single framework for AV IO on all platforms, or at least GNU/ 
>> Linux and Mac OS X.
>
> which is great (esp. as Gem should already be there :-))
>
>
>>>> Check out all of the codec libs that are included.
>>>
>>> obviously these is exactly not the point of having a plugin- 
>>> architecture...
>> I don't understand. not?
>
> that was the unneccessary harsh part of my mail.
> however, let me explain:
> plugins (as used e.g. by gmerlin) are used to create a flexible  
> bridge between two "applications"; if the code-base of appA changes,  
> then appB does not need to know anything about this change; if appA  
> is totally unavailable, most functionality of appB will be untouched  
> (e.g. Gem can be seen as a bridge between openGL and Pd; openGL  
> doesn't know nor care which Pd version we have; nor the other way  
> round; it's part of Gem's task to track any incompatible changes in  
> either of them; if openGL is entirely missing on a system, this  
> doesn't affect Pd as a whole; it will make Gem unusable, but you can  
> still play nicely with Pd)
>
> this is even more true with decoder-plugins: if the Sorenson2000  
> codec is missing on my system, i still might be able to decode  
> motion jpeg videos; my application should continue to work even  
> without any plugins installed. if i need a special codec not  
> installed on my system, my task should be to install the missing  
> codec and not to update my application. (now , that's an important  
> statement here)
>
> obviously, to make a platform to work with in a reasonable way, an  
> application might choose to ship with some plugins. (and i think  
> that is your point here)
>
>
> what i mainly wanted to oppose with my rant was, that by embracing  
> gmerlin/gavl in the way it is done know (that is: fully including  
> the source into PdX), you are giving away to good things about it.
> in one of my former mails i have written: "the ffmpeg-nightmare is  
> delegated to a single-point: gavl".
> by including the sources of gavl/gmerlin, the near impossible task  
> of tracking changes of ffmpeg is back with us: whenever ffmpeg  
> changes sufficiently (that is: each other week), gmerlin will have  
> to adopt. then we will have to import the new gavl sources, in order  
> to support the new ffmpeg version.
>
> otoh, having a stable API in gavl/gmerlin enables us to just link  
> against gmerlinj/gavl "once", and ship (with) "a" decoder-plugin for  
> ffmpeg, and once this is outdated, the decoder-plugin could be  
> updated, rather than the entire PdX. and less dependencies to wait  
> for.
>
>
>
> all in all, my point about plugins is that they are plugins, thus  
> externally loadable and updateable pieces. the sole idea of plugins  
> lies within this externality. (else we could just statically link  
> everything in)
>
> i guess your point about pugins is, that they are totally useless  
> unless you have them. (else we could talk about black holes and  
> whatelse, with an equal impact on Pd)
>
> like always, we are both right.


On Mac OS X, the ffmpeg, gavl, gmerlin, etc. stuff is all shipped as  
dylibs in Pd-extended.app/Contents/lib, just like VLC does it.  OSX is  
crippled as compared to Debian with package management, so this turns  
out to be the best way to manage this stuff.  If you want, you could  
swap out those dylibs with newer versions for the 'plugin'-ability.

Windows is a about the same, so the idea with the Pd-extended  
installer is that it installs the DLLs for the codecs.

The tricky question for now is on Debian/Ubuntu.  gmerlin-decoder is  
not in Debian or Ubuntu.

.hc


----------------------------------------------------------------------------

                                               http://at.or.at/hans/