There is a confirmed problem with the WMA 9.1 Standard codec: VBR encoding results in bigger file sizes (and higher bitrates) as compared to the WMA 9 codec, with the same quality settings.
For example, files encoded with WMA9 and a VBR90 quality setting (
Normal/High in MC) average at 199kbps and 5.3MB per file, which happens to be my preferred quality vs. file size compromise. With the same quality setting, files encoded with WMA9.1 average at 298kbps and 8.8 MB - a 50% increase.
Going down to VBR75 in WMA9.1 (
Normal in MC) results in average bitrates (and file sizes) that are lower than WMA9/VBR90 (too low for me).
This bug is described in
http://www.hydrogenaudio.org/forums/lofiversion/index.php/t27037.html and
http://www.tech-archive.net/Archive/Media/microsoft.public.windowsmedia.encoder/2004-09/0061.html.
The latter post also describes a workaround that may be of interest to MC 11 users that are a) concerned about the above, and b) haven't upgraded to Windows Media Player 10 yet (which would have already installed the WMA9.1 codecs.)
So if you are using Windows Media Player 9 (which had WMA9), you may want to do the following before/after upgrading to MC11:
1. BEFORE RUNNING MC11 UPGRADE
a) Check version of the WMA encoder installed on your system by locating file c:\windows\system32\wmadmoe.dll. Look at the Version tab of the Properties dialog box. If the version starts with "9" (typically 9.0.0.3250), then you have the WMA9 codec, and if the version starts with "10" (10.0.0.3646), then you already have WMA9.1. In the latter case, stop here, since it's too late:)
b) Otherwise, create a local folder, e.g. c:\WMA9DMO
c) Copy c:\windows\system32\wmadmoe.dll c:\WMA9DMO
2. RUN MC11 UPGRADE
3. AFTER MC11 UPGRADE
a) Make sure no media application (MC, WMP, WME, etc.) is running
b) In a command window, register the old encoder through: regsvr32 c:\WMA9DMO\wmadmoe.dll
c) Launch MC11 and do your ripping. This should use the old WMA9 codec.
NOTE that the above only changes which *encoder* is used; it doesn't change the *decoder* (wmadmod.dll) which after the MC11 upgrade will be the WMA9.1 version (which is backwards compatible.)