Subject: Re: [AVT] [dispatch] Proposal to form Internet Wideband AudioCodec WG

From: "Michael Ramalho (mramalho)" <[email-masked]>
Date: Mon, 20 Jul 2009 14:20:29 -0400

Keith,

Comments in-line w/MAR:

Regards,

Michael A. Ramalho, Ph.D.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
DRAGE, Keith (Keith)
Sent: Thursday, June 04, 2009 6:01 AM
To: Dan York; [email-masked]
Cc: [email-masked]
Subject: Re: [AVT] [dispatch] Proposal to form Internet Wideband
AudioCodec WG

I would argue that G.711 is implemented, not because anyone can
implement it, but because everyone else has implemented it. It
essentially forms the lowest common denominator for interoperability. If
fancy codec x doesn't work, then assuming you have the bandwidth
availabile, G.711 probably will. And I suspect it is royalty free not
because it was always so, but because any IPR that existed has pretty
much expired by now.

G.711 is also the one codec that is probably the most neutral to
transcoding. I can do to codec A to G.711 and back to codec A with less
impact that with any other intermediate codec.

MAR: Let's look at that statement. G.711 is a simple *waveform* codec
that achieves a (single frequency) SNR of approximately 25 dB over an
approximate 25 dB dynamic range. The reason why you can "go to G.711 and
back" is simply that the other (narrowband) codecs you use have less
fidelity (i.e., on average much more distortion - or equivalently lesser
SNR). The distortion introduced by G.711 is less than the distortion
already introduced by the other codecs.

MAR: An equivalent statement is that for the 0 - 4kHz band (narrowband),
25 dB SNR is good enough for telephony.

For wideband there probably is not any one codec that has achieved that
position.

MAR: Well, the game changes with VOICE when it comes to wideband. Speech
has a spectral tilt to it - lesser power per Hz with increasing
frequency (as it comes from a finite energy acoustic source - this MUST
be the case in the limit). The end result is that a PSD for an ensemble
of speech signals has approximately 6dB less energy per octave (i.e.,
over all phonetic content).

MAR: If you use G.711 for wideband (16k sampling) - the higher
frequencies will have more distortion (i.e., much less than 25 dB). Thus
G.711 sounds somewhat bad in wideband application due to this.

MAR: What I believe you are asking for is: 1) a simple "waveform codec",
2) but one that is "pre-equalized" to whiten the spectral tilt in speech
signals. For example, virtually all filter-band-based codecs (e.g.,
MLT/MCT-based) do this via the "bit allocation" process (sometimes in
conjunction with pre-emphasis).

MAR: I believe most of the codecs proposed for this proposed "codec"
working group are speech-model based. If you want a "waveform based"
solution that you can "transform into and out of" (something which I
call a "do-no-harm" codec property) - you simply need pre-equalization
plus a relatively simple waveform codec behind it (G.711 or something
nearly as simple).

MAR: Note these codecs will be less bandwidth efficient than the usual
(model-based) suspects - as the model-based codecs generally only
parameterize the spectrum (NOT the waveform) above 4kHz. But give me
60~90 kbps ... and such a codec becomes a relatively easy task for any
signal processing graduate student (at least one that would have me on
their thesis committee).

MAR: Lastly, waveform based codecs are generally better for speech
recognition applications - a quality that we might also desire to
consider.

I don't believe building a better, even royalty free codec, will
guarantee a position in the market place. The world is littered with
better solutions that never made it. You need a market where everyone
chooses to implement it so that you can use that codec without having to
go to transcoding. Pasting IETF on the front cover does not achieve
that.

I don't really have a problem with people trying to sit down and design
a new codec and IETF then publishing it. Without some other selling
point however it just becomes yet another codec competing for market
place. As such, put it somewhere where it does not interfere with other
work. Sticking it on a separate mailing list, and not letting it compete
for valuable IETF face to face slots as a working group is fine.

regards

Keith

---

From: Greg Herlein <[email-masked]>
Date: Mon, 20 Jul 2009 12:08:42 -0700

I agree completely:  it's work worth doing.  My primary work is not around
audio these days but the lack of a standardized INTERNET voice codec is
holding things back, in my opinion.  The value of getting at least something
out there would spawn some application development of whole new application
classes.   I'd hoped that speex would have this effect but it took us too
long to get the payload to an RFC level... and part of that was not having a
broad enough base of support in the IETF community.  I think this effort
could build that base and hopefully create enough standardization that more
applications will get built that can interoperate.

I won't be in Stockholm but I vote yes.  We should do this work.  I'll help
as much as I can.

Greg

On Tue, Jun 2, 2009 at 9:15 AM, Henning Schulzrinne <[email-masked]>wrote:

> I view this as a trade-off. If we pursue this, there are risks:
>
> - nothing may come of it since there are no experts willing to help
> - somebody will claim IPR on the resulting work
> - the quality of the codec may not be competitive
>
> However, if we don't do this, we are stuck with the status quo, which is
> not all that satisfactory. Thus, unless there are significant costs for
> "innocent bystanders", I see this as a risk worth taking. In the worst case,
> we are no worse off than we are today. In all other cases, we'll have an
> additional choice for a wideband codec, even if it's not "the best", just
> "good enough". After all, most people use G.711 today, which has a really
> hard time making that claim.
>
> Most real work in the IETF is done by very small teams, typically less than
> 10, so as long as we have a handful of people that are willing to
> contribute, this can work. It might even work better, since you may get
> fewer people who have half-baked opinions - we may skip the binary vs. XML
> debates...
>
> We can set some ground rules ("must be tested with packet loss of 5%") and
> then see what happens. Compared to most network protocols, the likely
> negative impacts (such as security or congestion control issues) of even a
> badly-designed codec are pretty limited.
>
> Henning
>
>
> On Jun 2, 2009, at 11:57 AM, Roni Even wrote:
>
>  Hi,
>> I do not want to sound like someone who is for IPR (I am not), but why
>> stop
>> at codec, let's require it for all IETF work. There are IPR on IETF work
>> which is must simpler, in my view, than wide band audio codecs.
>>
>> I think that we can start with "royalty free" even though I am not sure
>> that
>> it will accepted as part of the charter of any other work group so why
>> pick
>> on codecs which require more work.
>>
>> This leaves the other reasons I heard for doing it at the IETF which is
>> the
>> price of participating (cheaper than being an ITU-T member) and maybe
>> design
>> less expensive characterization tests.
>>
>> Roni
>>
>>
>> From: Jean-Marc Valin [mailto:[email-masked]]
>> Sent: Tuesday, June 02, 2009 6:14 PM
>> To: Roni Even
>> Cc: 'Slava Borilin'; [email-masked]; 'Jason Fischl'; [email-masked];
>> [email-masked]
>> Subject: Re: [AVT] [dispatch] Proposal to form Internet Wideband Audio
>> Codec
>> WG
>>
>> Hi,
>>
>> Roni Even wrote:
>>
>>>
>>> I am not sure what prevented you from doing it today at the ITU or
>>> MPEG, why do you see the IETF handling it differently.
>>>
>>> I would also like to remind you and Jean-Marc that once you are
>>> bringing work to a standard body it may require collaboration with
>>> other people who will have other proposals that will also address the
>>> same requirements and you may need to invest money in comparative
>>> testing by independent listening labs.
>>>
>>> I also think that you will need to supply the codec in source code and
>>> provide copy right to the IETF.
>>>
>>>
>> I am well aware that bringing work to the IETF would require
>> collaboration with others. I am not seeking control over the work I am
>> currently doing and would really welcome such collaboration. The idea is
>> only to have the best wideband codec possible without IPR issues. Given
>> the ITU and MPEG track record, I think it would be very unlikely for any
>> of those organisations to work on an IPR-free codec.
>>
>> I also agree with Henry that "the Internet has different criteria than
>> ITU-T networks may have". Internet adoption follows different patterns
>> than adoption in the ITU primary target markets. For example, the
>> Internet has more consumer-reconfigurable software, while the ITU has to
>> deal with a lot of fixed hardware deployments. At the ITU, it makes
>> sense to invest large sums of money into testing and characterisation of
>> codecs because the codecs deployed there usually stay around for a long
>> time and the infrastructure investments are usually very large. On the
>> other hand, I would say the investments in codecs for the Internet are
>> comparatively smaller and, while testing is still important, it is not
>> as critical as it is for the ITU.
>>
>> It's also a choice one has to make. It is unlikely that companies would
>> invest money in expensive testing if they are not going to obtain
>> royalties in return. However, I think we may be able to define some more
>> lightweight (collaborative?) testing that is sufficient and doesn't
>> involve as much investments as what the ITU does. For the Internet, I
>> believe an IPR-free codec that everyone agrees performs well is better
>> than a patent-encumbered codec that has had more extensive testing. This
>> is again another difference with the ITU: patent-encumbered codecs tend
>> to hurt a lot more on the Internet because many applications (e.g.
>> giving away the client) are very hard (or impossible) when one has to
>> pay per-channel royalties.
>>
>> As for the source code issue you pointed out, all the Xiph codecs are
>> already published under a very permissive open source license (BSD), so
>> this would not really change.
>>
>>   Jean-Marc
>>
>>  Roni
>>>
>>>
>>>
>>> *From:* [email-masked] [mailto:[email-masked]] *On Behalf
>>> Of *Slava Borilin
>>> *Sent:* Monday, June 01, 2009 11:50 PM
>>> *To:* [email-masked]
>>> *Cc:* [email-masked]; Jason Fischl
>>> *Subject:* Re: [AVT] [dispatch] Proposal to form Internet Wideband
>>> Audio Codec WG
>>>
>>>
>>>
>>> Agree with Jean-Marc.
>>> SPIRIT is interested to contribute as well - having a dozen of
>>> proprietary
>>>
>> codecs developed, including
>>
>>> one specifically desgined for internet (SPIRIT IP-MR, which is now under
>>>
>> WGLC on draft-ietf-avt-rtp-ipmr-04) -
>>
>>> multi-rate, scalable, adaptive, wideband codec.
>>>
>>> We can also continue this work with IETF.
>>>
>>> Moreover, most if not all efforts coming from ITU on codecs unfortunately
>>>
>> are NOT really focused on
>>
>>> internet-specific codecs (that's why several companies have had to
>>> invent)
>>>
>> - as ITU preference is mainly
>>
>>> specific (i.e. cellular) networks at first.
>>>
>>> however, as we see the greant rise of pure "internet-basd communications"
>>>
>> (skype, webex/citrix, and many others) -
>>
>>> we all (and users) are suffering from inefficiency in all currently
>>>
>> "standard" codecs and ambiguity in the choice of
>>
>>> internet-targeted ones.
>>>
>>> Again, we probably can put together enough number of contributors to the
>>>
>> WG to have the expertise.
>>
>>>
>>> regards,
>>> Slava Borilin
>>>
>>> --
>>> John Lazzaro wrote:
>>>
>>>   A traditional response to this type of request is to note that the
>>>
>> IETF
>>
>>>
>>>   really doesn't have much in the way of expertise in audio codec
>>>
>> design.
>>
>>>
>>>   I don't see many of the regulars who present at the AES codec paper
>>>
>> sessions
>>
>>>
>>>   posting here on AVT (ditto ICASSP paper sessions for voice codecs).
>>>
>> It's
>>
>>>
>>>   a full-time job to keep up-to-date and contribute to that
>>>
>>>   signal-processing lore.
>>>
>>>
>>>
>>> Well, there's no reason that the IETF cannot build such an expertise
>>> in audio codecs. This is actually something in which I'd be interested
>>> in getting involved and I'm sure others at Xiph.Org would be
>>> interested as well. We have several people with audio codec expertise
>>> from working on Vorbis, Speex and (more recently) CELT. It turns out
>>> that the CELT codec currently under development at Xiph actually meets
>>> most of the requirements from the original proposal in being a very
>>> low delay codec with adaptive bit-rate and sampling rate (up to 48
>>> kHz), scalable complexity, and good robustness to packet loss. We'd be
>>> willing to continue the development with the IETF. Even if not with
>>> CELT, it's still like to be involved in such a new WG.
>>>
>>> Cheers,
>>>
>>>  Jean-Marc
>>>
>>
>> _______________________________________________
>> Audio/Video Transport Working Group
>> [email-masked]
>> https://www.ietf.org/mailman/listinfo/avt
>>
>>
> _______________________________________________
> Audio/Video Transport Working Group
> [email-masked]
> https://www.ietf.org/mailman/listinfo/avt
>

-- 
Greg Herlein
www.herlein.com

---

From: Roni Even <[email-masked]>
Date: Tue, 21 Jul 2009 00:41:30 +0300

Greg,

I am not sure that the reason the payload took that long had to do with
support in the IETF or why you say that there was no support. I looked back
on the progress of the work and noted that between 2003 and 2005 and between
2005 and 2007 you stopped working on the draft (that is a total of 4 years)
and the AVT chairs has asked you about it. I noticed that Colin responded
whenever you submitted a new revision or asked questions.  

Progress of the work depends on the authors and not on the IETF or the AVT
chairs.

Thanks

Roni even

From: [email-masked] [mailto:[email-masked]] On Behalf Of Greg
Herlein
Sent: Monday, July 20, 2009 10:09 PM
To: Henning Schulzrinne; [email-masked]
Subject: Re: [AVT] [dispatch] Proposal to form Internet Wideband Audio Codec
WG

Greg

On Tue, Jun 2, 2009 at 9:15 AM, Henning Schulzrinne <[email-masked]>
wrote:

However, if we don't do this, we are stuck with the status quo, which is not
all that satisfactory. Thus, unless there are significant costs for
"innocent bystanders", I see this as a risk worth taking. In the worst case,
we are no worse off than we are today. In all other cases, we'll have an
additional choice for a wideband codec, even if it's not "the best", just
"good enough". After all, most people use G.711 today, which has a really
hard time making that claim.

Henning

Hi,
I do not want to sound like someone who is for IPR (I am not), but why stop
at codec, let's require it for all IETF work. There are IPR on IETF work
which is must simpler, in my view, than wide band audio codecs.

I think that we can start with "royalty free" even though I am not sure that
it will accepted as part of the charter of any other work group so why pick
on codecs which require more work.

This leaves the other reasons I heard for doing it at the IETF which is the
price of participating (cheaper than being an ITU-T member) and maybe design
less expensive characterization tests.

Roni

-----Original Message-----
From: Jean-Marc Valin [mailto:[email-masked]]
Sent: Tuesday, June 02, 2009 6:14 PM
To: Roni Even
Cc: 'Slava Borilin'; [email-masked]; 'Jason Fischl'; [email-masked];
[email-masked]
Subject: Re: [AVT] [dispatch] Proposal to form Internet Wideband Audio Codec
WG

Hi,

Roni Even wrote:

  Jean-Marc

Roni

Agree with Jean-Marc.
SPIRIT is interested to contribute as well - having a dozen of proprietary

internet-specific codecs (that's why several companies have had to invent)

internet-targeted ones.

regards,
Slava Borilin

--
John Lazzaro wrote:

IETF

design.

sessions

It's

  signal-processing lore.

Cheers,

 Jean-Marc

-- 
Greg Herlein
www.herlein.com

---

From: Greg Herlein <[email-masked]>
Date: Mon, 20 Jul 2009 15:32:28 -0700

Roni,  I don't disagree.  I meant support in the meta-sense.  There's a
chicken before the egg problem in that companies tend to not use something
like Speex (for products) until there's a stable standard, but to get to the
standard you do need some commitment from the authors.  In our case, we were
independants and not being paid by an employer to provide the work effort to
the IETF.  The IETF and AVT chairs were quite supportive as were the IETF
community.   Where we needed support was from a company or companies who saw
the business value in contributing author effort and productization.
Without that it was left to the heard efforts of the authors on their own
time.

My hope is that an effort to standardize on a wideband voice codec will be
seen as a valuable business effort by a broad-based collection of companies
with IETF participants.    I think it's worth the effort because it will
expand the ecosystem for new products and services that can leverage an open
network with voice quality substantially better than POTS.    As long as
there are multiple royalty laden propriary codecs on the menu it's harder
for the ecosystem to evolve - each participant has to support some set of
codecs and where they don't match up with others you don't have an
ecosystem.  If we can standardize around a voice codec and payload - like we
standardized around TCP/IP (yes, I remember coding for Banyan VINES when
that was not a given) - then we can start something bigger.

Greg

On Mon, Jul 20, 2009 at 2:41 PM, Roni Even <[email-masked]> wrote:

> *From:* [email-masked] [mailto:[email-masked]] *On Behalf Of *Greg
> Herlein
> *Sent:* Monday, July 20, 2009 10:09 PM
> *To:* Henning Schulzrinne; [email-masked]
>
> *Subject:* Re: [AVT] [dispatch] Proposal to form Internet Wideband Audio
> Codec WG
>
>
>

-- 
Greg Herlein
www.herlein.com