[asterisk-dev] iLBC codec

[Steve Underwood]

On 07/13/2011 01:18 AM, Artem Makhutov wrote:
> Hi,
>
> Andrew Latham schrieb:
>> On Tue, Jul 12, 2011 at 12:29 PM, Steve 
>> Underwood<steveu at coppice.org>  wrote:
>>> On 07/12/2011 11:50 PM, Kevin P. Fleming wrote:
>>>>
>>>> On 07/12/2011 10:10 AM, Klaus Darilion wrote:
>>>>>
>>>>> Hi!
>>>>>
>>>>> I just stumbled about
>>>>> https://sites.google.com/site/webrtc/ilbc-freeware
>>>>>
>>>>> Has somebody checked the new license? Maybe this would allow 
>>>>> Asterisk to
>>>>> include ilbc codec again in the Asterisk sources and build it by 
>>>>> default.
>>>>
>>>> We have not taken the time to review the new license, no. There is so
>>>> little demand for iLBC to be included directly in the Asterisk code 
>>>> that it
>>>> hasn't seemed like it would be worth the effort. If someone out 
>>>> there wants
>>>> to review the license and give us an initial assessment of whether it
>>>> appears to be GPLv2 compatible, that would be a helpful start.
>>>>
>>> On the mailing list for Opus the subject of iLBC has come up a 
>>> couple of
>>> times, and people like Cisco said iLBC is heavily used in numerous
>>> commercial applications. None of the open source VoIP software seem 
>>> to find
>>> much demand for it. Interesting difference. The floating point 
>>> source code
>>> which GIPS published in the RFC is quite slow, and can potentially be
>>> speeded up quite a lot. Demand is so low that nobody has ever asked 
>>> me to
>>> attempt that. I suspect Cisco may be shipping lots of copies, just 
>>> because
>>> iLBC is part of the cable VoIP spec, but I think people don't really 
>>> use it.
>>>
>>> Steve
>>
>> Like Steve says, it is a listed feature, but rarely implemented...
>
> Many hardphones have the iLBC codec implemented: Grandstream, Cisco, 
> Yealink...
>
>> Can anyone give an example of a system that requires this codec and no
>> other?
>
> This is a bad question. What system require speex, g729, g723 or what 
> ever codec and no other? Most devices support many codecs.
>
> The main benefit of iLBC codce is that is has a _MUCH_ better audio 
> quality then g729 and still requires pretty low bandwith and you do 
> not have to pay license fees for using ilbc...
iLBC actually sounds a little worse than G.729, despite running at twice 
the bit rate. What you have probably experienced is the effect of 
chaining a cell phone codec with G.729 and iLBC. Any chaining of 
multiple low bit rate codecs produces horrible results, but G.729 + cell 
phone is far worse than G.729 + iLBC. This can make it an interesting 
option.

>
> I am using ilbc and I would like to see it in asterisk core. It is 
> pretty annoying to compile it manually every time...
People complain about the CPU load of the open source iLBC. If you are a 
serious user, have you ever looked into whether someone might speed it 
up for you?

Steve