[jitsi-users] Can anyone recommend a codec


#1

Hi Everyone,

After the discussion last week on the dangers of using VBR codecs in secure voice communications, I decided to limit the codecs I use in secure calls to iLbc/8000 and G.722 both of which I believe to be non-VBR.

Of course, 8000 gives a pretty low quality sound. Very tolarable but not as good as say 16000 or the ultra-wideband codecs do.

My question is: can anyone recommend a good non-VBR codec?

Anthony

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Sent from my mobile device


#2

Anthony Papillion wrote:

Hi Everyone,

After the discussion last week on the dangers of using VBR codecs in
secure voice communications, I decided to limit the codecs I use in
secure calls to iLbc/8000 and G.722 both of which I believe to be non-VBR.

Of course, 8000 gives a pretty low quality sound. Very tolarable but not
as good as say 16000 or the ultra-wideband codecs do.

My question is: can anyone recommend a good non-VBR codec?

Anthony

--
Sent from my mobile device

At least on Linux with PulseAudio the PCMU codec works very well (with
ALSA it has lower quality). It is also the most compatible codec out there.
I guess there is always a tradeoff - either more secure calls or more
sound quality. Anyway, the guys who did that paper with the vbr issues
tested the speex codec so im not sure how Silk is doing in the same
circumstances.
BTW if you want really secure calls, dont ever rely on third party
servers - just set up a direct vpn and use direct calls (or install a
jabber/sip server).

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--
O zi buna,
Kertesz Laszlo


#3

Thanks. I'll give PCMU a try and see how it goes. Honestly, I'm not
looking for much. I'm just about completely happy with ILBC and G.722 at
8000. It's about telephone quality and that's tolorerable. I suppose the
only reason I want more data is for the call to be less effected by
dropped or lost packets. With ILBC, I'm having a lot of breaks in the
audio that I wasn't having with the higher rate codecs.

As to the VPN or Jabber server, I've looked at setting up a private
Jabber server. That seems most secure and, since I believe Jabber is
federated, shouldn't present much of a problem for non-local users either.

Anthony

···

On 5/28/2012 11:25 PM, Kertesz Laszlo wrote:

Anthony Papillion wrote:

My question is: can anyone recommend a good non-VBR codec?

Anthony

--
Sent from my mobile device

At least on Linux with PulseAudio the PCMU codec works very well (with
ALSA it has lower quality). It is also the most compatible codec out there.
I guess there is always a tradeoff - either more secure calls or more
sound quality. Anyway, the guys who did that paper with the vbr issues
tested the speex codec so im not sure how Silk is doing in the same
circumstances.
BTW if you want really secure calls, dont ever rely on third party
servers - just set up a direct vpn and use direct calls (or install a
jabber/sip server).


#4

Thanks. I'll give PCMU a try and see how it goes. Honestly, I'm not
looking for much. I'm just about completely happy with ILBC and
G.722 at 8000.

iLBC is one of the CODEC that have the upmost MOS with PCMA/U.

It's about telephone quality and that's
tolorerable. I suppose the only reason I want more data is for the
call to be less effected by dropped or lost packets. With ILBC,
I'm having a lot of breaks in the audio that I wasn't having with
the higher rate codecs.

This isn't normal: iLBC has been designed especially to cope (very)
well with packet loss - in fact, it is ZE CODEC for packet loss, any
other can't take the comparison when you lose packets.

So, either there's a glitch in Jitsi implementation or may be a CPU
hunger: on my old C-2.0GHz it eats the whole CPU and voice's choppy
whatever the CODEC; or the quality of your line isn't good enough
(throughput is not the only point, latency and linearity in debit
are important too <= some providers apply (hard) traffic shaping that
kills VoIP, especially in france).

As to the VPN or Jabber server, I've looked at setting up a private
Jabber server. That seems most secure and, since I believe Jabber
is federated, shouldn't present much of a problem for non-local
users either.

Use ejabberd, doc's scattered, but it is able to handle many users
with very low ressource.

JY

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On Tue, 29 May 2012 03:07:47 -0500 Anthony Papillion <anthony@papillion.me> wrote:
--
Women give themselves to God when the Devil wants nothing more to do
with them. -- Arnould