[Vorbis] oggenc -q switch vs -b switch

[codered12 at gmail.com]

Hello folks

I am encoding music to ogg vorbis format for the first time. From what
i have researched, ogg vorbis is natively a vbr format. Also encoding
using the -q switch is encouraged instead of specifying a bitrate
through -b.

Now, while encoding using -b i get this:

Encoding "file.wav" to
         "file.ogg"
at approximate bitrate 224 kbps (VBR encoding enabled)

Notice the VBR encoding enabled message.

But when i specify a quality through -q, no VBR encoding enabled message
is displayed, and mediainfo http://mediainfo.sourceforge.net/ also
displays the Bit rate mode as Constant.

So, what should i do to get VBR encoded files instead of CBR.

Thanks.