Windows – VLC streaming, setting for Logitech QuickCam at low resolution isn’t working

I can stream my Logitech QuickCam S5500 in Windows 7 using the following vlc command:

vlc dshow:// :dshow-vdev="Logitech QuickCam S5500" :dshow-adev=none :dshow-size=320x240 :dshow-fps=30 :no-dshow-config :no-dshow-tuner :live-caching=3000 :sout=#transcode{vcodec=h264,vb=0,scale=0,acodec=mp4a,ab=128,channels=2,samplerate=44100} :sout-keep

However, when I receive the stream (with VLC or other programs such as iSpy), the resolution of the stream (and camera) is 1280×960. I confirmed this by doing CTRL-I in VLC when it's playing dshow:// and looking at codec info. I also confirm it's too big because I have about 0.25 FPS. I've tried shortcuts for resolution, such as qis, etc. The QuickCam stays in 1280×960 no matter what.

I'm able to get my QuickCam to work with iSpy in direct mode using 320×240 yielding roughly 12 FPS, although this rate seems to fluctuate significantly (between 6 and 21). I'm hoping that VLC will smooth it out to solve this problem.

I've tried different (bogus) values of dshow-size, e.g., dshow-size=320×640, and VLC complains my device doesn't support them and refuses to stream. So I know it's somehow parsing the value and validating it.

Any ideas why the webcam is stuck in 1280×960 with VLC?

Alternative solution: anyone know how to specify the resolution of the QuickCam on the VLC plugin in iSpy? The documentation is thin on what arguments are passed, referring only to VLC's site and not how those arguments are used in the VLC plugin-in in iSpy.