[Gambas-user] gb.media : receiving GStreamer element messages

[Benoît Minisini]

Le 11/05/2015 02:52, Adrien Prokopowicz a écrit :
> Hello everyone,
>
> So I wanted to play a bit with the "spectrum" GStreamer element.
> After reading the documentation, I noticed that it used "element messages"
> to send the spectrum data to the application, but gb.media does not have
> an interface to catch these.
>
> I made a quick and dirty patch at first, but I think that after some
> cleanup
> it would be nice to share. So here it is (see the attached patch).
> (I named the data class MediaData here, but I think there might be
> a better name for it.)
>
> In order to see it in action, I made a small application that shows
> the spectrum of an audio file while playing it.
> It also tweaks the data to look nicer on the visualizer (basically
> changing the frequency scale to a logarithmic one, and smoothing the
> result),
> but you can disable it in the configuration menu if you want.
>
> The app itself is completely useless, but I find it quite fun to watch.
> However, processing and rendering the data takes a significant amount of
> power, so it might lag if you have a small CPU.
> If it lags too much for you, you can lower some rates in the
> SpectrumPlayer class.
>
> What do you think ?
>
> Regards,
>
>

Cool. Can you change a bit your implementation so that is it more generic?

The idea is replacing the Data event and the MediaData object by a 
Message event and a MediaMessage object.

Instead of testing GST_MESSAGE_ELEMENT, you check before the switch that 
the Message event is implemented (with GB.CanRaise), and then you send 
the event handler a newly create MediaMessage object.

The MediaMessage object is exactly like your MediaData object, except 
that you can add the Type property for the message type, and constants 
in the MediaMessage class (or in the Media class) for each message type. 
And in the future we'll be able to add other methods if needed.

If can you do the change, just commit it directly. Easier for me to 
check that way!

Regards,

-- 
Benoît Minisini