Hello People, can't encode video from camera

[junglemike]

hello everyone.
I made some 50 3-min clips with canon A70 camera (it can shoot video for 3min only). Camera encodes video in Mjeg format with video bitrate around ~5000kbps. I have no problem playing back the clips - this is because I have directshow filter (decoder) which can decode this video. Also Mplayer and VLC can play it w/o problem. But when i want to re-encode this clips in x264 with .mkv container i get this:
virtualdub can encode those because it has internal mjpeg decompressor (or at least it says so)
But i need to do a little filtering, this is the avisynth script :

LoadPlugin ("c:\Program Files\AviSynth 2.5\plugins\FluxSmooth.dll")
LoadPlugin ("c:\Program Files\AviSynth 2.5\plugins\convolution3d.dll")
LoadPlugin ("c:\Program Files\AviSynth 2.5\plugins\undot.dll")
AVISource("O:\to send3\23.avi",false)
lanczosresize(464,352)
ConvertToYUY2()
undot()
FluxSmoothT()
Convolution3D (0, 3, 4, 3, 4, 2.8, 0)

megui says me that it didn't find appropriate decompressor:


Where can i get a FREE decompressor /codec for avisynth that can handle this format?
In case more info is needed - this is the virtualdub info on the file itself (not script):

[jagabo]

ffdshow
PicVideo MJPEG codec

[junglemike]

Thanks for the input. I installed latest ffdshow, but avisynth still won't open the scripts. Maybe i need to include some dll with loadplugin()?
PicVideo is 30$. Well I would prefer a freeware decoder, it such exist.

[guns1inger]

Try using DirectShowSource instead of AVISource in your script. I believe FFDShow's mjpeg is a directshow filter

[jagabo]

ffdshow has both Directshow and VFW MJPEG decoders. But I think they aren't enabled by default.

For Virtualdub you need to enable the VFW MJPEG decoder. Use Start -> All Programs -> ffdshow -> VFW Codec Configuration. Select the "decoder" tab, "codecs" in the left pane, MJPEG in the right pane, use the pulldown to select "libavcodec".

It's similar for Directshow but start with Start -> All Programs -> ffdshow -> Video Decoder Configuration.