[asterisk-users] drop dead fix

[Mark Deneen]

On Fri, Oct 15, 2010 at 10:41 AM, Danny Nicholas <danny at debsinc.com> wrote:
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Steve Edwards
> Sent: Friday, October 15, 2010 9:21 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [asterisk-users] drop dead fix
>
> On Fri, 15 Oct 2010, Danny Nicholas wrote:
>
>>               I am about to have to dump Asterisk in favor of some other
>> VOIP/PBX solution;  the reason?  I have 304 voice prompts recorded as
>> 22Khz wav format files that sound like crumpling paper whenever I
>> convert them to the 8Khz wav/gsm format required by Asterisk.  I was
>> considering trying the G.729 codec, but reading through the specs, I see
>> that the 8Khz conversion is going to dump me into the same pile of
>> dung.  Any body have any suggestions?
>
> Can you post a link to a sample "before" and "after" file as well as the
> command line you are using to convert the file?
>
> The sox line I am using (version 14.0.1) is
> Sox foo.wav -r 8000 -c 1 bar.wav resample -ql
>
> Before I found Audiograbber I used this line
> Sox -v 2 foo.wav -r 8000 -c 1 bar.wav resample -ql
>

Play them on a telephone so that you know how it will sound to users.
You can't compare them on headphones, because 8000Hz will never sound
as clear as 16KHz or 22KHz.

I've had decent luck using high and low pass filters in sox.


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

The values you pick for highpass and lowpass depend on your recordings.

-M