[asterisk-users] Sox and bad quality when converting to 8 kHz

[Mark Deneen]

On Thu, Mar 24, 2011 at 4:58 PM, Thomas Winter <thowinter at googlemail.com> wrote:
> Hi list,
> I have an 44100 Hz file with human voice, stereo with 16Bit.
> When convertig this to 8 kHz, mono I loose a lot of quality and have
> some ground noise. I tried several sox options but without success.
> Can somebody help....
>

I have had good results with this:

sox in.wav -r 8000 -c 1 out.wav highpass 500 lowpass 4000 resample -ql

Play around with the high and low pass numbers because they might need
to be changed depending on the properties of your recordings.

-M