stevek at stevek.com
Sat Jun 11 13:45:32 PDT 2005
On Jun 11, 2005, at 4:29 PM, Jean-Marc Valin wrote:
> Le vendredi 10 juin 2005 à 21:27 -0400, SteveK a écrit :
>> I'm not an expert either, but I see people choosing iLBC over speex
>> all the time with asterisk; partly it's because they have more
>> market share in hardphones, and partly it's because of marketing and
>> such. (another reason is that iLBC source is included in asterisk,
>> and speex is only compiled in if you have the speex development stuff
>> on your machine when you compile asterisk [i.e. the speex-devel
>> package]). Some comments below:
> Well, it's clear that the marketing department for iLBC is a bit
> than that for Speex ;-) I can't comment on hardphone market share
> I have no idea about the iLBC market share (or even that of Speex).
> However, I think that the (relatively recent) fixed-point should make
> Speex much more interesting for embedded devices.
It should -- but we'll have to see if it does. iLBC is supported by
a handful of hardphones; I haven't heard of any that support speex yet.
>> There's a wideband version of iLBC, but it's not free(as in beer).
>> Skype uses this. (Actually I'm not 100% sure it's called speex, but
>> GIPS makes it, and it's probably closely related).
> "Not sure it's called Speex"?? I suppose you meant something else?
Oops. That was a thinko -- I meant I'm not sure if they just call it
wideband iLBC, or if there's some other name for it.
>> since there's so many speex options, it depends on the options you
>> choose. Asterisk presently has poor defaults, and most people link
>> against speex-1.0 code. If you use the latest speex code, and use
>> SSE optimizations, and complexity 2, you get very comparably
>> performance from speex as compared to iLBC. The iLBC reference code
>> is not well optimized, though.
> Not sure how speed is that relevant on a PC. With the current version,
> you can encode+decode between 50 and 150 channels (depending on
> quality/complexity), which is probably enough for most applications.
It can never be too fast :). It's totally possible to have 4, 8, or
12 PRI spans terminate on a single box (several quad-span PRI cards)
and that's between 92 and 276 channels. Coming soon are T3 cards,
which is a few more channels again :)
With the right options, speex is competitive -- but the perception
(at least in the asterisk community) is that it's very slow.
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