asterisk users - Nov 2007 - Bad audio quality in 1.4-SVN when encoding to alaw/ulaw

----- Original Message -----
From: Bernhard Schmidt
[mailto:berni at birkenwald.de]
To: asterisk-users at lists.digium.com
Sent: Wed,
28 Nov 2007 14:49:24 -0400
Subject: [asterisk-users] Bad audio quality in
1.4-SVN when encoding to alaw/ulaw

> Hi,
Greetings and salutations.
 
> for all tests where Snom360 was the only client on my side you can use
> ekiga and get the exact same results, so this rules out a problem with
> Snom. You can use ulaw instead of alaw without changes.
> 
> The pattern here is quite clear, as soon as Asterisk needs to encode
> alaw/ulaw, sound gets bad.
> 
> Does anyone have any clue what might be causing this?
What version of GCC are you building with? There is currently an issue open,
http://bugs.digium.com/view.php?id=11243, with codec_gsm that seems to stem from
GCC 4.2 performing optimizations on the code. Building with DONT_OPTIMIZE
enabled in make menuselect fixes it for now, or using another version of GCC.

Joshua Colp
Software Developer
Digium, Inc.

Hi,

after some years of abstinence from bigger Asterisk installations I was
trying to give it a start again with the asteriskv6.org project. I ran
into some issues regarding the audio quality and tried the vanilla 1.4
code, with the same results.

I have asterisk (latest 1.4 branch checkout from SVN) running on my home
server (Linux 2.6.22.11, two HFC BRI cards with latest mISDN from git).
I have had very bad call quality as soon as Asterisk needs to encode
something into alaw/ulaw (choppy sound). I tried two different clients
(Snom 360 hardphone and ekiga on my workstation), the network in between
is fine. 

Snom360 ---- SIP/alaw ---- Asterisk voiceprompts (demo application)
           <---------------- bad
	   ----------------> unknown

Snom360 ---- SIP/gsm  ---- Asterisk voiceprompts (demo application)
           <---------------- good
           ----------------> unknown

Snom360 ---- SIP/alaw ---- Asterisk ---- IAX/gsm ---- Digium (demo)
           <---------------- bad
	   ----------------> unknown

Snom360 ---- SIP/gsm  ---- Asterisk ---- IAX/gsm ---- Digium (demo)
           <---------------- bad
	   ----------------> unknown

Snom360 ---- SIP/alaw ---- Asterisk ---- SIP/alaw ---- ekiga
           <---------------> good (both with reinvite and without)

Snom360 ---- SIP/alaw ---- Asterisk ---- SIP/ulaw ---- ekiga
           <---------------> bad
 

Snom360 ---- SIP/gsm  ---- Asterisk ---- mISDN/(alaw?)
	   <---------------- good
           ----------------> bad

Snom360 ---- SIP/alaw ---- Asterisk ---- mISDN/(alaw?)
           <---------------> good

for all tests where Snom360 was the only client on my side you can use
ekiga and get the exact same results, so this rules out a problem with
Snom. You can use ulaw instead of alaw without changes.

The pattern here is quite clear, as soon as Asterisk needs to encode
alaw/ulaw, sound gets bad.

Does anyone have any clue what might be causing this?

Thanks,
Bernhard

Bernhard Schmidt wrote:
> I have had very bad call quality as soon as Asterisk needs to encode
> something into alaw/ulaw (choppy sound). I tried two different clients
>   
Check your version of GCC.  If seen posts that pointed me to resolve 
this issue. 

Under Mandriva 2008, they are using "4.2.2 20070909 (prerelease)". 
This
is why I have to stick with Mandriva 2007.1 which is using 4.1.2 
20070302 (prerelease).  The transcoding audio was awful!

Doug


-- 
 
Ben Franklin quote:

"Those who would give up Essential Liberty to purchase a little Temporary
Safety, deserve neither Liberty nor Safety."

Bernhard Schmidt <berni at birkenwald.de> wrote:

Update:
> Snom360 ---- SIP/alaw ---- Asterisk voiceprompts (demo application)
>            <---------------- bad
> 	   ----------------> unknown
>
> Snom360 ---- SIP/gsm  ---- Asterisk voiceprompts (demo application)
>            <---------------- good
>            ----------------> unknown
Voiceprompts (MusicOnHold here) were stored in WAV format, so Asterisk
had to encode in both cases. As soon as I install alaw MOH files the
sound is crystal clear.

Regards,
Bernhard