On Tue, Apr 7, 2009 at 9:42 AM, seven du <seven@idapted.com> wrote:

And, actually the value to be normalized is 32bit and which generally
is a sum of two 16bit values( read and write ), so it's probably easy
to exceed 32767 if both end speaking at the same time.

On Apr 7, 2009, at 12:15 PM, Nic Bellamy wrote:

> Anthony Minessale wrote:
>> 2) the macro is designed to fight clipping:
>> When a sample exceeds the max size of the datatype we set it to
>> the max value then cut the volume in half of that sample so it does
>> not make too much noise. if we divide everything by 2 then all the
>> volume would be reduced even on samples that fell inside the proper
>> range.
> Hi Anthony, all,
> this is, in my opinion, actually going to give you far far uglier
> audio artefacts than simply hard limiting the samples. Rather than try
> and describe the resulting distortion, it's easier to just listen to
> it
> in action...
>
> Each of the following files is about 100kb.
>
> Original file (extracted from
> freeswitch-sounds-en-us-callie-8000-1.0.7.tar.gz):
> http://www.vadacom.co.nz/engineering/ivr-sample_submenu.wav
>
>
> After 30dB gain and hard limiting samples to between -32768 and 32767:
> http://www.vadacom.co.nz/engineering/ivr-sample_submenu-
> hardlimited.wav
>
>
> After 30dB gain and switch_normalize_to_16bit():
> http://www.vadacom.co.nz/engineering/ivr-sample_submenu-switch_normalize_to_16bit.wav
>
>
> Cheers,
> Nic.
>
> --
> Nic Bellamy,
> Head Of Engineering, Vadacom Ltd - http://www.vadacom.co.nz/
>
>
> _______________________________________________
> Freeswitch-dev mailing list
> Freeswitch-dev@lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev
> http://www.freeswitch.org

_______________________________________________
Freeswitch-dev mailing list
Freeswitch-dev@lists.freeswitch.org
http://lists.freeswitch.org/mailman/listinfo/freeswitch-dev
UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-dev
http://www.freeswitch.org