Document GStreamer plugins

[sbstp]

This is part of a gstreamer plugin for the opus codec. I need access to this enum to set the plugin's property to a value from this enum.

It's not documented on the website and I don't know how to access it.

[lazka]

Hm, producing any documentation for GStreamer codecs would be vastly different to anything currently implemented. We should be able to list properties and new types which have GType at least through introspection...

You can just use integers in the mean time:

BITRATE_TYPE_CBR = 0
BITRATE_TYPE_VBR = 1
BITRATE_TYPE_CONSTRAINED_VBR = 2

[sbstp]

Someone on the gstreamer irc suggested using Gst.util_set_object_arg(oenc, 'bitrate_type', 'constrained-vbr'), and indeed, it works well.