[gst-devel] gstplay / gstmediaplay / etc...

[Thomas Vander Stichele]

> Well, it's not possible to extract any data, not even metadata, without
> playing a pipeline if you look at it from the GStreamer point of view.
> And it is more than difficult to have a second set of libs/plugins which
> are used to extract metadata, especially with the number of different
> formats and sources GStreamer supports.

Well, that really depends on how you do it.  I've thought it over after
hadess's comments on IRC and I think that it probably is a good idea to be
able to extract metadata before playing it.
I've installed freeamp once and when it opened a directory with five
thousand mp3 files it started behaving very unresponsively.  I don't want
that with gstreamer-based players or with rhythmbox.  It's all in the app
of course, but if the only way to get at metadata is by setting up pipes
and iterating them a bit this might end up taking a long time too.

Compare this with xmms which is pretty fast in getting all the id3 tags
for example.

Also, atm I don't really see how we're going to get duration from an mp3
file without doing un-GStreamer-like calculations based on file length.

So I think that we really should start planning on this, and I think there
is merit in setting up a "general" metadata library that provides the
common stuff and attaching "specific" helper functions to the
plugins/elements that provide mime types.  I know I once programmed a few
calculation functions for audio duration vs framelength and stuff like
that might help to do these things...

So in effect I think we should try and do it through pipelines if it isn't
a big slowdown, but otherwise, for player applications, it makes sense if
gstreamer provides a library to get at metadata.  If we leave it up to the
app everyone will do it in a different way.

Thomas

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