Bug#482717: Latest gstreamer0.10-ffmpeg breaks gnome

[Reinhard Tartler]

Fabian Greffrath <greffrath at leat.rub.de> writes:
>> However, a doable solution has been proposed here. lu_zero, the gentoo
>> ffmpeg maintainer suggested that we should install an altivec disabled
>> libavcodec in /usr/lib and an altivec enabled version in
>> /usr/lib/altivec. First very simple tests show the expected result.
>
> Erm, does any other package in Debian do it this way? Is this even FHS
> compliant? Will altivec systems know where to find 'their' libs or will
> there be other magic involved?

We rely here on the dynamic linker doing the right thing [tm] here. In
order to understand how this work, please execute the following command
on your system `LD_LIBRARY_PATH=/lib:/usr/lib LD_DEBUG=libs /bin/true`.
It will show you the search path of libraries in your
system. /usr/lib/altivec comes before /usr/lib.

As for FHS compliance, well, since even libc6 is doing this, I'd think
this is okay.

>> Furthermore this leads to maintaining
>> a build matrix for the following flavors:
>>
>>  - static
>>  - dynamic, noopt
>>  - dynamic, MMX (amd64, i386)
>>  - dynamic, altivec (powerpc)
>>  - dynamic, VIS (sparc)
>>
>> and so on.
>
> May I assume that packages like gstreamer0.10-ffmpeg depend on 'dynamic,
> noopt' in the first place and that other, optizmized library packages
> may be installed additionally or as a replacement on architectures that
> support it? 

I'd say we install all variants in a single package and let the dynamic
linker choose the right library.

> If it is possible at all, why don't we provide non-altivec
> shared libs by now?

because of this comment in debian/rules:

# Don't disable altivec, at least for now. Disabling altivec causes a
# FTBFS in libswscale, as it will fallback to a "plain c version" of
# some functions, which only compile with altivec enabled.
#nooptflags += --disable-altivec

Unfortunately, I forgot to add references (bugno or buildlog) to this
problem. Damn.

Sebastian, could you please investigate this issue? I'll be working on
building the flavors in paralell.

-- 
Gruesse/greetings,
Reinhard Tartler, KeyID 945348A4