[asterisk-dev] Underwood's spandsp

[Lee Howard]

Steve Underwood wrote:

> Tzafrir Cohen wrote:
>
>>
>> iaxmodem is distributed with a specific version of spandsp. Is that the
>> trick?
>>  
>>
> Which trick? iaxmodem comes with a fairly recent snapshot of spandsp. 
> It uses things which are not in spandsp-0.0.2.


There are a few reasons why iaxmodem comes with a copy of spandsp rather 
than having the user go out and fetch a copy...

1) iaxmodem uses the T.31 library which is only in the development 
branch (0.0.3) of spandsp, and guiding a typical user to the right place 
would be time-consuming... I'd be spending a lot of time doing that, 
trying to steer people away from 0.0.2

2) I want to minimize the amount of problems that iaxmodem users have, 
and so I want to be able to test and sign-off on any particular snapshot 
before iaxmodem users expect anything from it.  The development branch 
is prone to lots of changes, and consequently sometimes those changes 
will break things that were working before.  Including a particular cut 
of spandsp allows me to shield the users from most of that.

3) The spandsp included with iaxmodem has at least two patches that 
Steve has not merged into spandsp.  He and I have discussed them.  Even 
though they only apply to T.31 they're apparently not appropriate 
patches for spandsp in general, but they are important for iaxmodem... 
at least until Steve and I can work out something better.

That said, there are no "tricks" to any of that which make iaxmodem 
magically work better.  Using IAXmodem and HylaFAX together approaches 
the fax solution in a different way than does rxfax/txfax, and the only 
shared code is the DSPs (i.e. V.29) and some aspects of libtiff 
(T.4/T.6) usage.  The rest of the code (i.e. T.30) is different.

Lee.