[asterisk-users] Questions regarding asterisk-opus package in Debian Stretch repo and Opus in general

[JM or AJS]

On 29/03/17 16:18, Olivier wrote:
> Hello,
>
> After reading [1] (in french), I would be very happy if I could get 
> answers to:
>
> 1. Does this 13.7+20161113-3 package version has any relation with 
> asterisk's version it complements ? Current asterisk version in repo 
> is 13.14.0. Does this 13.7 complies with it ?
Debian's versioning scheme is all their own.  And I would not expect it 
to work with anything but a Debian-packaged Asterisk.

Stretch is currently the "testing" distribution.  This means that new 
versions of packages could appear at any time; but if a newly-introduced 
package breaks any other packages, they will be removed from "testing"  
(and replaced as soon as possible with newer, compatible versions)  
rather than allow packages to exist in the repository that cannot be 
co-installed.

If you really want to use a newer Asterisk version, the Debian source 
will contain a file called "rules", which is really a Makefile "in 
disguise".  This should give you a good clue as to how to hand-build an 
equivalent based on more up-to-date Source Code (if the compile-time 
options have not changed too much, then you might even get away with 
using it directly, but consider this a bodge).
> 2. From package description, is this package enough or not to allow 
> transcoding with G711 ?
> For instance, in the following situation:
> SIP Phone <---- Opus ----> Asterisk <---- G111 ---> ITSP
All codecs can input and output raw, uncompressed PCM; so as long as you 
build all the relevant modules, your Asterisk will be able to transcode 
between any two codecs it supports.

(Is "G111" a typo for "G711" ?)
> 3. Can you share here any personal field experience with this codec, 
> for home worker use case ?
> Is there a better user experience with Opus than with G729 or G711 ?
Opus is, to the best of my knowledge, fully Open Source.  G729 was 
encumbered by patents in some jurisdictions, though it's now patent-free.

G.711 A-Law is what the PSTN uses natively, and that is unlikely to 
change anytime soon; though some VoIP providers are bringing Opus online 
already.  If you have many phones connected to your Asterisk, then you 
may run into CPU limitations transcoding incoming and outgoing calls 
between G711 and Opus.  But that depends on your Asterisk server.  If 
you are recording calls, Asterisk will already have to convert both the 
incoming and outgoing legs to raw PCM anyway.  In any case, if your 
provider supports Opus, you can offload the donkey work to them .....
> 4. Does it work on ARM boxes (Raspberry, ...) ?
The only thing that would prevent any software from working on ARM / 
Raspberry Pi would be if it
contained any architecture-specific binary code without Source Code 
(which you could just about get away with, if you released it under LGPL 
plus exceptions or an Apache licence).  And I suspect if any such code 
existed, it would be rewritten in fairly short order anyway.

Also, it's Debian; and they really, really don't like binary blobs, only 
grudgingly banishing them to a special "non-free" section which is not 
even enabled by default.  And that package was in the main repository, 
suggesting full Source Code availability.  In any case, I see builds for 
armhf  (R.Pi 1 and 2)  and arm64  (R.Pi 3);  so even if there is some 
sneaky binary-only component, you will be able to get it to work.
>
> [1] https://packages.debian.org/stretch/asterisk-opus
>
> Regards
>
>
--

JM or AJS

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