Subject: PSQM (P.861), PSQM+, PAMS

From: Massimo Fubini <[email-masked]>
Date: Sun, 2 Jul 2000 15:40:31 +0200

I would like to know if there are free, or not too expensive,
implementation of an algorithms to have an objective measurement for
voice quality. It is for a research, and non commercial activity!

I was thinking about PSQM, PSQM+ or PAMS.

Do you know if the ITU-T P.861 (PSQM) standard also contain an implementation
of the algorithms (on the itu web site it is written it contains a
floppy disk, but I can't understand what is in it)

Best regards,
 Massimo Fubini                         mailto:[email-masked]

University of Rome La Sapienza - Netlab CNR

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From: Orion Hodson <[email-masked]>
Date: Mon, 03 Jul 2000 11:00:34 +0100

> floppy disk, but I can't understand what is in it)

No, it doesn't.  The P.861 (02/98) disk is labelled as 'C
implementation of ...', but only contains reference vectors.  My
experience from implementing P.861 is that it contains a couple of
vagueries that make it difficult to implement.  I was able to get the
short-term verification tests work, but not the longer term ones.  I
failed to connect with anyone in the ITU capable of providing
clarification.

I have an implementation of Stephen Voran's MNB algorithm
http://www.cs.ucl.ac.uk/staff/O.Hodson/misc/mnb-0.1e.tar.gz.  This
algorithm, it's callibration, and performance, are described in two
papers by Voran in IEEE Trans. speech and audio processing, Vol7, No4,
July, 1999.  You can modify this source to form P861-appendix2-mnb
without too much effort.  The implemention builds cleanly for Solaris,
FreeBSD, Irix, Linux, porting to other platforms should be trivial.
Commercially interested parties should contact Stephen Voran if they
want to use or implement this algorithm.

Wonho Yang, Majid Benbouchta and Rober Yantorno have an algorithm
Modified Bark Spectal Distortion (MBSD) and will provide source code
if you ask ([email-masked],[email-masked]).  The
algorithm is described in ICASSP98, Vol1, pp541-544, Seattle, 1998.

A problem in most of these algorithm's is thresholding.  They involve
a thresholding step of the reference and modified signal.  Only frames
that have energy above the threshold's are included in the final score
computation.  This is a problem if you have packet losses and are
using silence substitution.  Yhe silence substituted frames do not get
included in the calculation, but are perceptually noticeable.  An
algorithm that takes this into account is described in 'Advances in
objective estimation of perceived speech quality', Stephen Voran,
Proc. 1999 IEEE Workshop on Speech Coding for Telecommunications,
Porvoo, Finland, June 1999.

Does anybody know the situation with PAMS?  I used to be sponsored by
BT, but they weren't interested in making it available without a fee.

cheers
- Orion

Orion Hodson                                   Research Student 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Networked Multimedia Research Group      Tel: ++(0)171 419 3704
Department of Computer Science           Fax: ++(0)171 419 1397
University College London, Gower Street, London,  WC1E 6BT,  UK     
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

"In the fight between you and the world, back the world." 
	--Frank Zappa

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From: "Alan Duric" <[email-masked]>
Date: Mon, 3 Jul 2000 14:35:56 +0200

Hi,

In addition to very descriptive answer that Orion provided, I would mention
that You should be awaiting a bit until ITU SG 12 releases P.862 (which is
basically ready at this point of time). P.862 will replace completely P.861
and it should handle large delays and jitter in adequate way (what You can
not say at all for P.861) and it is tailored for VoIP.
Unfortunately PAMS is not available in any other way beside commercial and I
did not heard from BT guys  that they are planning to do so.

Regards,
Alan Duric
Global IP Sound
www.globalipsound.com

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Monday, July 03, 2000 12:01 PM
To: Massimo Fubini
Cc: [email-masked]
Subject: Re: PSQM (P.861), PSQM+, PAMS

cheers
- Orion

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From: Henning Schulzrinne <[email-masked]>
Date: Mon, 03 Jul 2000 09:54:45 -0400

See http://www.cs.columbia.edu/~hgs/rtp/quality.html for a listing of a
number of references. The paper by Voran, for example, can be found at
the http://www.its.bldrdoc.gov/home/programs/audio/audio.htm web site.
-- 
Henning Schulzrinne   http://www.cs.columbia.edu/~hgs