[Speex-dev] Resampler

[Daniel Schmidt]

Hello Jean-Marc,

thank you for your answer!

> I'll look into this. There's basically no overflow prevention for now.
> I'll think about how to add that without affecting performance too much
> (on CPUs that don't have hardware saturation). I'm  open to suggestions :-)

I'm not sure if I can really help, but I did a few more tests.
Reducing the volume of the input signal by 6 dB and increasing it
again afterwards with saturation seems to avoid the overflow even with
heavy clipping. So using 14 fractional bits internally instead of 15
and doing the saturation right before converting to the 16 bit output
sample value could help. But certainly there are more sophisticated
solutions to this problem. :-)

During the tests I encountered another problem. While upsampling a
continuous –6 dB sine from 8000 Hz to 11025 Hz I heard that the
resampler produces a click every 5 seconds. After changing the output
sample rate to 11000 Hz the clicking disappeared.

Daniel