[Speex-dev] SPEEX Fixed Point Development

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Thu Feb 14 16:56:13 PST 2008

Wayne Klein wrote:
> We are in the process over the next week to implement the Fixed Point
> algorithms into a 200 MHz ARM9 CPU with MMU and I was wondering if you
> had any experience/knowledge with possible pitfalls.  

All I can say is that if your chip supports the ARM5E DSP-like
instructions, you can probably get a good speedup.

> We are running
> Fixed Point compilation on PC based system (P4 processor) and are
> noticing that the audio gets “noisy” and then comes back to a more
> normal voice.  Are you aware of any issues with the fixed point application?

Nothing I'm aware of, though it could happen if your signal is already
clipping or close to the clipping point. Send a (short) sample if you
want me to have a look at it. Also, compiling with fixed-point debugging
enabled (--enable-fixed-point-debug or FIXED_DEBUG) could tell you if
there's an overflow problem somewhere.



More information about the Speex-dev mailing list