asterisk users - Apr 2011 - 1.8.4-rc2: ReceiveFAX fails

On a test fax:

     -- Executing [s at incoming-fax:1] Set("DAHDI/4-1", 
"FAXFILE=/var/spool/asterisk/fax/20110415_1825") in new stack
     -- Executing [s at incoming-fax:2] Answer("DAHDI/4-1",
"") in new stack
     -- Executing [s at incoming-fax:3] ReceiveFAX("DAHDI/4-1", 
"/var/spool/asterisk/fax/20110415_1825.tif") in new stack
     -- Channel 'DAHDI/4-1' receiving FAX 
'/var/spool/asterisk/fax/20110415_1825.tif'
     -- Channel 4 detected a CED tone towards the network.
[Apr 15 18:25:52] WARNING[5600]: res_fax_spandsp.c:367 spandsp_log: 
WARNING T.30 ECM carrier not found
[Apr 15 18:25:52] WARNING[5600]: res_fax_spandsp.c:367 spandsp_log: 
WARNING T.30 ECM carrier not found
   == Spawn extension (incoming-fax, s, 3) exited non-zero on
'DAHDI/4-1'


/var/spool/asterisk/fax exists, but no file 20110415_1825.tif is created.

Using spandsp-0.0.6-pre18, the Jan 22 release.

Do the log notes of the CED tone or the T.30 ECM warning have anything 
to do with this?

chan_dahdi.conf:

[pstn]
context=incoming-pstn-line ; Incoming calls go to [incoming-pstn-line]
  in extensions.conf
faxdetect=incoming
faxbuffers=>6,full  ; who knows what this does
busydetect=yes
dahdichan => 4

Any idea on how to debug this?

sean

On Fri, Apr 15, 2011 at 07:00:27PM -0400, sean darcy wrote:
...
> Do the log notes of the CED tone or the T.30 ECM warning have anything  
> to do with this?
I can't help with this.
> faxbuffers=>6,full  ; who knows what this does
But I do know that this "faxbuffers" policy basically is telling the
kernel to
allow ~120ms of audio to build up before shipping it out to the physical
board. This is to work around problems where scheduling jitter on the host
computer would prevent the asterisk process from keeping the DAHDI channel
full and fax machines do not handle gaps in the audio very well.

This is more pertinent if you're connecting a real fax machine to an FXS
port.

Cheers,
Shaun

-- 
Shaun Ruffell
Digium, Inc. | Linux Kernel Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: www.digium.com & www.asterisk.org

On Fri, Apr 15, 2011 at 7:00 PM, sean darcy <seandarcy2 at gmail.com>
wrote:
> Using spandsp-0.0.6-pre18, the Jan 22 release.
>
You might try using spandsp-0.0.6-pre17. That version works great for
me with 1.8.4-rc2. When I tried pre18 it failed to receive any faxes.

Ryan