[Speex-dev] Speex over 56.6K modem

[Tay YueWeng]

Dear all,

Have anybody uses speex codec over 56.6K bit/s line
that hear clearly in both direction before? I perform
a testing with one side using 56.6K dialup modem and
the other side using broadband. The user that uses
56.6K/s modem is able to hear the broadband user
voice.  But the broadband uses hardly understand
56.6K/s modem user's voice. I am using 16KHz encoding.
I am not sure if the the modem is half or full duplex.

Of course, there is nothing wrong Speex but I am just
wondering what is the mimimal bandwidth requirement
for speex under 8KHz and 16KHz? 

So far, I have enabled VBR and DTX. What more should I
do to optimize the bandwidth utilization? 

Is Speex codec design with 56.6Kb/s bandwidth
consideration?

It seems to me that the amount of bandwidth
utilization for 8KHz and 16KHz is almost the same
after compression, is this normal?

Thanks,
YueWeng

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