Summary:	ASTERISK-03339: ISDN4Linux driven devices only present a lot of noise.
Reporter:	unnet (unnet)	Labels:
Date Opened:	2005-01-24 06:00:18.000-0600	Date Closed:	2008-01-15 15:23:08.000-0600
Priority:	Major	Regression?	No
Status:	Closed/Complete	Components:	Core/General
Versions:		Frequency of Occurrence
Related Issues:
Environment:		Attachments:	( 0) asterisk.i4l-law.diff
Description:	If a call is made where an ISDN4Linux device is in the path it will only generate scatter/gather/noise and misc debris as audio. It seems it has something to do with the removal of the duplicate alaw implementation (chan_modem_i4l.so 1.21) ****** STEPS TO REPRODUCE ****** Upgrade asterisk to CVS-HEAD 24-01-2005 12:23 and call using a ISDN4Linux card. You will hear the noise. ****** ADDITIONAL INFORMATION ****** A CVS HEAD checkout from 21-01-2005 00:00 will work correctly.
Comments:	By: Mark Spencer (markster) 2005-01-24 07:55:13.000-0600 In which direction does the audio sound bad? By: Mark Spencer (markster) 2005-01-24 07:58:09.000-0600 Also please try latest CVS (version 1.22) which may fix the problem. By: unnet (unnet) 2005-01-24 08:08:18.000-0600 It sounds bad in both directions.Version 1.22 of chan_modem_i4l.c does not fix this problem. The sound is so bad that it's total static and nothing else looks like a codec issue. By: Paul Cadach (pcadach) 2005-01-24 14:09:13.000-0600 Asterisk's A-law and I4L's one have different (reversed) bit order. mu-law looks like have equivalent translation tables. Please, verify attached patch (just move from A-law to mu-law). Thanks. By: unnet (unnet) 2005-01-24 14:39:02.000-0600 Attached patch works here. I'm now running last CVS (24-01-2005 21:37 CET) with the attached patch and ISDN4Linux works flawlessly. Audio works on both sides. By: Paul Cadach (pcadach) 2005-01-24 15:01:08.000-0600 I don't know why A-law and mu-law uses different (reversed) bit orders between Asterisk and ISDN4Linux. Currently, mu-law is the same between Asterisk and I4L, but A-law is reversed at I4L (A-law's "idle" codes is 0x55/0xD5 but for ISDN4Linux this is 0xAA/0xAB respectively). Moving I4L part to mu-law should fix all compatibility issues between Asterisk and ISDN4Linux parts, what was done by attached patch. By: Mark Spencer (markster) 2005-01-24 15:41:20.000-0600 Fixed in CVS head, thanks! By: Russell Bryant (russell) 2005-01-27 18:20:20.000-0600 only an issue in head By: Digium Subversion (svnbot) 2008-01-15 15:23:07.000-0600 Repository: asterisk Revision: 4886 U   trunk/channels/chan_modem_i4l.c ------------------------------------------------------------------------ r4886 | markster | 2008-01-15 15:23:06 -0600 (Tue, 15 Jan 2008) | 2 lines Fix chan_modem_i4l to be sure we use unsigned (bug ASTERISK-3339) ------------------------------------------------------------------------ http://svn.digium.com/view/asterisk?view=rev&revision=4886 By: Digium Subversion (svnbot) 2008-01-15 15:23:08.000-0600 Repository: asterisk Revision: 4887 U   trunk/channels/chan_modem_i4l.c ------------------------------------------------------------------------ r4887 | markster | 2008-01-15 15:23:07 -0600 (Tue, 15 Jan 2008) | 2 lines Fix law table (i4l) (bug ASTERISK-3339) ------------------------------------------------------------------------ http://svn.digium.com/view/asterisk?view=rev&revision=4887