Re: [hylafax-users] how is vgetty implemented these days?

["Luke McKee" <hojuruku@xxxxxxxxx>]

Lee,

You are completly right. I hadn't RTFM yet.
I relied  on the ebuild on gentoo didn't have a dependency for
spandsp. I'll get it fixed.

Wouldn't it be great if IAX modem could RE-INVITE or use NSE to
convert the connection to use T.38 if the remote gateway supported
that protocol?

I read your comments on the FAQ about T.38. Now that spandsp is
supporting T.38 will you add support to IAXmodem too?

As for V.34 support it's best implemented in hardware. I thought I
read about it somewhere. I know capi4hylfax has got references to V.34
in changelog
"    * set minimum of 4800 for V.34 primary rate renegotiations (02 Apr 2006)
   * improve handling of V.34 control channel retrain (02 Apr 2006)"

So the code is already in the public domain for doing V.34 in a
softdsp. It would be nice to get it implemented in spandsp too!
Capi4hylafax pays it's licensing fees because it's intended to works
with Fritz hardware. Would there be patent issues putting it into
spandsp?

Cheers,

Luke

On 25/04/07, Lee Howard <faxguy@xxxxxxxxxxxxxxxx> wrote:
> Luke McKee wrote:
>
> > SpanDSP which can be used with asterfax to answer incoming fax calls
> > is planning to add V.34 support.
>
>
> This is news to me.  I bet it's news to Steve Underwood, too. (Unless
> he's holding back on me.)  ;-)
>
> > Lee - thinking of making a new faxgetty compatible application that
> > uses spandsp?
> > http://www.soft-switch.org/
> > http://www.voip-info.org/wiki/view/spandsp
>
>
> Thanks.  I'm quite familiar with spandsp.  You've mentioned iaxmodem a
> few times.  I thought you knew...
>
> > It's also worth noting that echo cancellation is good for voice, but
> > when receiving a fax you need to turn it off.
>
>
> Echo cancellation, if it were flawless, would cancel out only the echo,
> and thus there would be no problem with it and fax.  However, echo
> cancellation on many VoIP products tends to foul up the audio in general
> - and since fax is largely a half-duplex communication anyway, there's
> really no reason to risk having the echo canceller do bad things when
> faxing.
>
> Lee.

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