Hi! I just want to share an answer to one of the concerns I posted:
The problem was and is : That comunication between most ATA and ekiga softphone
can be made with only two codecs: G711 and G726. (G729 is pattented so ekiga
doesn't use it).
So comunication with G711 has so good quality but just when bandwith is good.
So the only option for low bandwith communication beteween ATA and ekiga
softphone is G726.
The problem is that communication between ekiga and ATA(and viceversa) with
G726 is too bad. The sound is bad, robotic and with noice. I didn't know wat
was the problem because I tried communication between ATA to ATA with this
codec and the sound was perfect. Then I tought the problem was ekiga.net sip
service and tried iptel.org sip service, but the problem between ATA to ekiga
softphone was the same. After googling the whole internet I think I found an
answer you can read in the link below:
http://lists.digium.com/pipermail/asterisk-users/2006-September/166357.html
There are actually two conflicting methods of packing G.726-32 samples
into bytes.
RFC 3551 has this to say:
Note that the "little-endian" direction in which samples are packed
into octets in the G726-16, -24, -32 and -40 payload formats
specified here is consistent with ITU-T Recommendation X.420, but is
the opposite of what is specified in ITU-T Recommendation I.366.2
Annex E for ATM AAL2 transport. A second set of RTP payload formats
matching the packetization of I.366.2 Annex E and identified by MIME
subtypes AAL2-G726-16, -24, -32 and -40 will be specified in a
separate document.
That's all well and good, but there are some phones out there that pack
samples into RTP payloads using the AAL2 direction. This causes interop
nightmares (i.e. your phones talk G.726-32, someone elses phones talk
G.726-32, but it sounds rubbish when you attempt a conversation). I
would guess that this might be why people avoid the G.726 codec.
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Thanks for all your hard work and voluntary time making ekiga!
Hernán.
Yahoo! Cocina
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