Summary:ASTERISK-13022: GSM sound quality degraded
Reporter:Thomas Omerzu (t-o)Labels:
Date Opened:2008-11-06 04:18:15.000-0600Date Closed:2009-04-27 15:36:36
Versions:Frequency of
Description:The sound quality of the standard GSM files is horribly degraded when listening to them on mISDN channels.


The problem does not occur on SIP channels. If I manually convert the GSM files to WAV files, sound quality will be back to what it was in

The problem is also present in 1.4.23-rc1.
Comments:By: Matt Riddell (zx81) 2008-11-06 13:11:14.000-0600

This sounds pretty much the same as the issue I reported about a year ago, and fixed with the inclusion of a smoother.  Will see if I can dig up the entry.

By: Matt Riddell (zx81) 2008-11-06 13:16:24.000-0600

Heh nah that was the opposite:


By: Kris Shaw (shawkris) 2008-11-28 06:25:33.000-0600

I have noticed the same problem with a SIP client - GSM prompts sound distorted when SIP client connects with ulaw/alaw.

Recompiling with DONT_OPTIMIZE resolves the problem.
Recompiling with libgsm 1.0.12 also makes the problem go away.

Asterisk version 1.4.22
gcc version 4.2.3

By: Leif Madsen (lmadsen) 2009-02-02 16:33:50.000-0600

t-o:  if you compile with GCC version 4.1, or with DONT_OPTIMIZE, do you get the same issue?

It seems that GCC has an issue from 4.2 and up that causes the GSM codec to have degraded sound quality. It is not a bug in Asterisk itself.


By: Thomas Omerzu (t-o) 2009-02-04 05:52:44.000-0600

I was not able to test it with gcc-4.1, but on the gcc-4.2.3 running here, the DONT_OPTIMIZE option definitely solves the problem!

By: Tilghman Lesher (tilghman) 2009-02-20 14:22:08.000-0600

dvossel:  see if you can determine why gcc might improperly optimize the assembly in codecs/gsm/inc/private.h

By: David Vossel (dvossel) 2009-04-14 16:05:24

unassigned this from myself, working on other issues at the moment and won't be able to start on it anytime soon.

By: Frank Waller (explidous) 2009-04-14 17:34:19

This is a oldie but goldie and seems to pop back up again and again, I wish I had the time to look deeper in fixing this then the little makefile workaround I provided in ASTERISK-10762 which is the same problem, also ASTERISK-11849 which is the same again suggests that it might be fix when using gcc 4.3.

By: Russell Bryant (russell) 2009-04-27 15:36:35

I'm closing this out as we think this is fixed when using a later version of gcc.