[Asterisk-Users] Asterisk - fax - spandsp

[Steve Underwood]

Jean-Yves Avenard wrote:

> Hello Steve
> On 15/05/2005, at 4:40 PM, Steve Underwood wrote:
>
>> The second parameter now says "treat this E1 as the first priority as 
>> the clock source". Your box should lock itself to the PSTN's clock. 
>> If that makes no sense, the bottom line is "this is good". :-)
>>
>>
>
> I do not know if it was from upgrading the linux kernel to 2.6.10, 
> turning off hyperthreading and changing the zaptel configuration line.

Possibly all of the above, but the clock source issue is *definitely* a 
factor. Hyperthreading causes trouble with zaptel on some machines. My 
entire dual xeon machine locks up solid using zaptel with HT on. With HT 
off that never happens.

>
> But the bottom line is this: "i now receive faxes perfectly!"
>
> As a side note regarding clock source, the documentation for 
> zaptel.conf states that 1 is for primary timing source, 2 is for 
> secondary and 0 is for not using this connecting as a timer source...
> Should it be that any number > 0 is in fact the priority for using it 
> as an external source?

The documentation does say that, but not very clearly. People like 
yourself seem to think "1 is for primary timing source" means the 
Asterisk box's port's internal clock will be the source of timing. It 
you think it through carefully, I think you should see that makes no 
sense. This box will feed out its clock on each port, and has no control 
over whether the other end slaves to it or not. "1 is for primary timing 
source" means "use one for the port which you want this box to slave to 
as the first priority". If your box cannot sync to the far end on that 
port (maybe the far end or the cable is dead), then "2 is for secondary" 
comes into play, and your box will try to sync to the port marked with a 
2. The Asterisk box will never attempt to slave to ports marked with a 
0. If all ports are marked with a 0, the Asterisk box will not slave to 
anything, and will try to be the master of its own universe.

Maybe someone should submit a patch which changes the documentation to 
something the average person will interpret correctly. It would have 
saved me at least a hundred hours of support hassles in the last year.

>
> I'm glad it works now.
>
> Is there any future support for fax in colours? just wondering, I 
> don't think I've ever used it before anyway :)

Priorities:
    1. T.38
    2. A more complete T.30
    3. ECM (which is really a part of 2)
    4. Things like colour FAX (which in part is part of 2, but requires 
all the compress/decompression and other stuff needed for grey scale and 
colour).

Regards,
Steve