Mine

gst-launch-0.8 { oggmux name=mux ! filesink location=re-encoded.ogg } filesrc location=to_re-encode.ogg ! decodebin name=d { d. ! queue ! ffmpegcolorspace ! theoraenc bitrate=300 ! queue name=theora-q max-size-buffers=0 max-size-bytes=10485760 max-size-time=0 ! mux. } { d. ! queue ! audioconvert ! audioscale ! audio/x-raw-int,rate=26000 ! audioconvert ! audio/x-raw-float,channels=1 ! rawvorbisenc bitrate=16000 ! queue name=vorbis-q ! mux. }

for some odd reason it doesn't work with theora-q parameters copied to vorbis-q. It also doesn't work without theora-q parameters...

thanks thaytan for the partial solution...