stereo usage of the echo canceler

Hello all.

A few questions on using speex's echo cancellation, for clarifying:

1) I assume that the echo_frame in this method:

speex_echo_playback(echo_state, echo_frame)

is just raw "pcm_s16le" type bits/data?  I'm a bit new to all this...

2) I assume from this thread:
http://lists.xiph.org/pipermail/speex-dev/2009-March/007151.html
that speex_echo_playback and speex_echo_capture only work with "mono"
input streams/samples?

Or is it the case that if I used init_mc then I could use
speex_echo_cancellation and pass it stereo samples?  What if I'm
multi-threaded (one thread out, one thread in), is it possible to use
speex_echo_cancellation in this instance?

Thank you very much.
-Roger-
-roger-