Re: GStreamer xwidget

[Po Lu]

Richard Stallman <rms@gnu.org> writes:

> Because I know nothing about GStreamer except what I've seen in these
> messages, I can't be sure of the implications of these facts.  I don't
> have enough context to fit them into.

Thanks, please see below.

> That suggests the feature might be ok -- but verifying that calls
> for some more discussion.
>
>                 as it doesn't depend on gst-plugins-ugly or gst-plugins-bad.

> You have mentioned gst-plugins-good, gst-plugins-ugly and
> gst-plugins-bad.  Can you tell me how they relate to GStreamer itself?

They are plugins maintained by the GStreamer developers, but are
separate from GStreamer itself.

> How does GStreamer interact with them?  Are they linked it by ld?
> Is it static linking?

They're not statically linked by GStreamer.  Instead, GStreamer will
dynamically link them depending on what the application requests.

> Does the choice of one of those inevitably have to be made when
> building Emacs?

No, see below.

> Does GStreamer ever use some sort of dynamic linking to select one of
> them?

GStreamer does, but it will not load any plugin Emacs doesn't ask it to.

> They say "plugins", not "plugin".  Is  there a separate plugin for each
> media format?

Yes, that is true.

> If so, does selecting gst-plugins-good statically link _all_ of the
> free plugins?  If not that, then what?

Asking for gst-plugins-base and gst-plugins-good will result in
GStreamer dynamically linking with the free plugins.  As long as Emacs C
code doesn't explictly tell GStreamer to load the ugly or bad plugins,
which are non-free, GStreamer will never load them.

The ugly and bad plugins are not installed with a default GStreamer
distribution either.  AFAIU, most GNU distributions do not have them in
their main package repositories either.