gtk – Gstreamer: how to achieve the same effect as ffmpeg filter tmix

The ffmpeg command can smooth video:

ffmpeg -i 1.h265 -vf "tmix=frames=3:weights=1 1 1" 2.h265

Now i want to use gstreamer to smooth but I can’t find the avfilter in gst-libav

gst-launch-1.0 filesrc location=1.h265 ! decodebin ! videoconvert ! avfilter filter="tmix=frames=3:weights=1 1 1" ! videoconvert ! gstsink

My question: Is there another way gstreamer can achieve the same effect as “tmix” in ffmpeg?
I tried chatGPT, but the effect was not.

gst-launch-1.0 filesrc location=1.h265 ! h265parse ! avdec_h265 ! videoconvert ! tee name=t \
t. ! queue ! identity single-segment=true ! videomixer name=mix sink_0::alpha=0.33 \
t. ! queue ! identity single-segment=true ! mix.sink_1 \
t. ! queue ! identity single-segment=true ! mix.sink_2 \
mix. ! gtksink