How to remove container from ffmpeg output?

Question

fmpeg

Purpose: to take from stdin u16le to recode it into opus and give it to stdout without a container.

What I'm stuck on:

ffmpeg -f s16le -ac 2 -ar 48000 -i o.pcm -t 0.01 -f opus pipe: -loglevel quiet

with opus format, ffmpeg gives it in the ogg container. but I only need codec data
how to remove the container?