Hi,
  I am talking of Advanced Version.
With Regards
Mihir Mody
	On Wed, 21 Feb 2001, alexander lerch wrote:

> Hello,
>
> Mihir Narendra Mody wrote:
> >
> > Hi,
> >   I agree with you to some extent. What we found that when signal
> > is nearly perceptually transpert, the ODG score is highly reliable.
> > But when then score is above -1 or -2 it is not much reliable. But
> > for high quality encoding the ODG has high correlation with SDG.
Actully
> > PEAQ standard discuuses all this issues and gives confindance levels,
> > various graph for many reference signals.
>
> Do we speak about the BASIC or the ADVANCED Model?
>
> Alexander
>
> --
> alexander lerch
> lerch@lerc...
>
> zplane.development
> holsteinische str. 39-42
> 12161 berlin
>  fon: +49.30.854 09 15.0
>  fax: +49.30.854 09 15.5
>
>
>
> _____________________________________
> Note: If you do a simple "reply" with your email client, only the
author of this message will receive your answer.  You need to do a "reply
all" if you want your answer to be distributed to the entire group.
>
> _____________________________________
> About this discussion group:
>
> To Join:  audiodsp-subscribe@audi...
>
> To Post:  audiodsp@audi...
>
> To Leave: audiodsp-unsubscribe@audi...
>
> Archives: http://www.egroups.com/group/audiodsp
>
> Other DSP-Related Groups: http://www.dsprelated.com
>
>
> ">http://docs.yahoo.com/info/terms/
>
>
	

Hi,
  That's true. LAME gives better quality (not NMR) then Fhg encoder
at 128kbps, 44.1khz test material.
With Regards
Mihir Mody,
Saken Communication Technology Ltd,
Bangalore - INDIA
	On Wed, 21 Feb 2001, Jeff Brower wrote:

> Mihir Narendra Mody-
>
> >  So there is not baseline in case of MP3. Usually all people compare
> >quality of their encoder to FhG Encoder(supposed to be best) for stereo
,
> >128 kbs, 48 khz refence signal.
>
> Yes I've heard this a few times, too.  I've also heard that at
other sample
> rates LAME encoder has better quality.
>
> Jeff Brower
> Signalogic
>
> >> Mihir Narendra Mody-
> >>
> >> >So differnt manufacture
> >> >can come up with differnt implementation and quality of
encoding is
> >> >differnt. The more knowlege and experiments done by
manufactures will
> >> >give better quality.
> >>
> >> So where is the baseline?  Where is the minimum level, testable by
an
> >> independently sponsored and impartial testing organization?  Such
a test must
> >> be
> >> developed for MP3 (and/or other audio codecs) before they can be
used in >>
> telecom
> >> and carrier class products.  The closest telecom analogy seems to
be echo
> >> cancellers, which also are improved constantly by different
manufacturers.
> >> But
> >> -- for echo cancellers there is a widely accepted performance
standard >>
> (G.165,
> >> G.168).  I guess MP3 is just not there yet.
> >>
> >> Thanks very much for discussion.  I think I understand the problem
better >>
> now.
> >>
> >> Jeff Brower
> >> DSP sw/hw engineer
> >> Signalogic
> >>
> >>
> >> On Tue, 20 Feb 2001, Mihir Narendra Mody <mihir@mihi...>
wrote:
> >> >Hi Jeff,
> >> >   In Mp3 standard, the decoder is standard and no much space
is left
> >> >for differernt manufacture to change it. Only they can use
fast algorithm
> >> >and resulting some error should not exceed specified value in
standard.
> >> >   The real thing or chanllenge they kept on encoder. The
algorithm
> >> >is not standardised but bitstream is standardized. So differnt
manufacture
> >> >can come up with differnt implementation and quality of
encoding is
> >> >differnt. The more knowlege and experiments done by
manufactures will
> >> >give better quality. For better quality you have to pay more.
There are
> >> >some reference wave files (like castanet, germal male speech)
are there
> >> >in audio coding. All manufacture have to specify the quality
(MOS score)
> >> >of this refence file by their encoder. There are some special
softeare
> >> >also
> >> >avaible (like OPERA from OPTICOM) which will give quality of
encoded
> >> >files. So while buuying you can ask the qulity of encoder on
this
> >> >benchmark signals.
> >> > I hope this will clarify your doubt
> >> >Regards
> >> >Mihir N Mody
> >> >Sasken Communication Techology Ltd
> >> >Bangalore, INDIA
> >> >
> >> >
> >> >
> >> >On Mon, 19 Feb 2001, Jeff Brower wrote:
> >> >
> >> >> Mihir Narendra Mody-
> >> >>
> >> >> Thanks for your informative reply.  It's more than I
thought was there, >>
> but
> >> >> still too imprecise.  There should also be conformance
streams for the
> >> encoder,
> >> >> given certain parameters.
> >> >>
> >> >> Given different levels of constraint, it should be
possible to perform
> >> bit-exact
> >> >> verification testing all the way through encode and
decode -- just like
> >> standard
> >> >> speech codecs.  I have a feeling this is one reason that
audio codecs >>
> other
> >> than
> >> >> MP3 may become the standard in AoIP / AoP systems in the
future, the way
> >> certain
> >> >> speech codecs are standard now.  Otherwise, it is
difficult for customers
> >> to
> >> >> know what they are getting.  It also makes it difficult
for telecom >>
> vendors
> >> to
> >> >> provide reasonable assurance on indemnification issues.
> >> >>
> >> >> Jeff Brower
> >> >> Signalogic
> >> >>
> >> >>
> >> >> >HI Jeff,
> >> >> >   When you buy CD from standard, in CD they give
some conformance
> >> >> >streams. Your decoder should able to decode and final
output error
> >> >> >should not exceed the error specified from reference
file. The exact
> >> >> >procedure for testing of decoder using mp3 file is
specified in part4
> >> >> >of standard (conformance testing).
> >> >> >  For encoder only restriction is that the bitstream
should confirm
> >> >> >the standard. The quality of encoded file depends on
Encoder
> >> >> >implementation ( quantizor, psycho-acoustics etc). So
output encoded
> >> >> >files of MP3 encoder are of different audio quality
depending on
> >> >> >the encoder implemetation, But decoder will able to
decode all
> >> >> >mp3 files. For high quality encoder, you have to pay
more.
> >> >> >Regards
> >> >> >Mihir Mody
> >> >> >Saken Communication technology Ltd
> >> >> >
> >> >> >
> >> >> >
> >> >> >On Mon, 19 Feb 2001, Jeff Brower wrote:
> >> >> >
> >> >> >> Mihir Narendra Mody-
> >> >> >>
> >> >> >> >  You can go to www.mpeg.org and its gives
many links to MP3 papers,
> >> >> >> >software etc. You can buy standard from ISO
site.
> >> >> >>
> >> >> >> One problem we have with calling the ISO site
"standard":  there are no
> >> >> standard
> >> >> >> input and output vectors to use for
bit-exactness verification.  I.e.
> >> there
> >> >> are
> >> >> >> no given .wav (or .aif) input files, .mp3 output
files, and resulting
> >> decoded
> >> >> >> .wav files for comparison.
> >> >> >>
> >> >> >> We also tried to get comparison files from
Fraunhofer, even going so >>
> far
> >> as
> >> >> to
> >> >> >> contact upper management.  Nothing.  Fraunhofer
has some .mp3 files on
> >> their
> >> >> >> site, but they appear to withhold the original
.wav files.
> >> >> >>
> >> >> >> So everyone's implementation of MP3 is
possibly -- likely at least
> >> somewhat
> >> >> --
> >> >> >> different, as long as it sounds Ok?  I guess so.
> >> >> >>
> >> >> >> Any comments on this issue are greatly
appreciated.
> >> >> >>
> >> >> >> Jeff Brower
> >> >> >> DSP sw/hw engineer
> >> >> >> Signalogic
>
	

Mihir Narendra Mody-

>  So there is not baseline in case of MP3. Usually
all people compare
>quality of their encoder to FhG Encoder(supposed to be best) for stereo ,
>128 kbs, 48 khz refence signal.

Yes I've heard this a few times, too.  I've also heard that at other
sample 
rates LAME encoder has better quality.

Jeff Brower
Signalogic

>> Mihir Narendra Mody-
>>
>> >So differnt manufacture
>> >can come up with differnt implementation and quality of encoding is
>> >differnt. The more knowlege and experiments done by manufactures
will
>> >give better quality.
>>
>> So where is the baseline?  Where is the minimum level, testable by an
>> independently sponsored and impartial testing organization?  Such a
test must 
>> be
>> developed for MP3 (and/or other audio codecs) before they can be used
in >> 
telecom
>> and carrier class products.  The closest
telecom analogy seems to be echo
>> cancellers, which also are improved constantly by different
manufacturers.  
>> But
>> -- for echo cancellers there is a widely accepted performance standard
>> 
(G.165,
>> G.168).  I guess MP3 is just not there yet.
>>
>> Thanks very much for discussion.  I think I understand the problem
better >> 
now.
>>
>> Jeff Brower
>> DSP sw/hw engineer
>> Signalogic
>>
>>
>> On Tue, 20 Feb 2001, Mihir Narendra Mody <mihir@mihi...> wrote:
>> >Hi Jeff,
>> >   In Mp3 standard, the decoder is standard and no much space is
left
>> >for differernt manufacture to change it. Only they can use fast
algorithm
>> >and resulting some error should not exceed specified value in
standard.
>> >   The real thing or chanllenge they kept on encoder. The algorithm
>> >is not standardised but bitstream is standardized. So differnt
manufacture
>> >can come up with differnt implementation and quality of encoding is
>> >differnt. The more knowlege and experiments done by manufactures
will
>> >give better quality. For better quality you have to pay more. There
are
>> >some reference wave files (like castanet, germal male speech) are
there
>> >in audio coding. All manufacture have to specify the quality (MOS
score)
>> >of this refence file by their encoder. There are some special
softeare
>> >also
>> >avaible (like OPERA from OPTICOM) which will give quality of
encoded
>> >files. So while buuying you can ask the qulity of encoder on this
>> >benchmark signals.
>> > I hope this will clarify your doubt
>> >Regards
>> >Mihir N Mody
>> >Sasken Communication Techology Ltd
>> >Bangalore, INDIA
>> >
>> >
>> >
>> >On Mon, 19 Feb 2001, Jeff Brower wrote:
>> >
>> >> Mihir Narendra Mody-
>> >>
>> >> Thanks for your informative reply.  It's more than I
thought was there, >> 
but
>> >> still too imprecise.  There should
also be conformance streams for the
>> encoder,
>> >> given certain parameters.
>> >>
>> >> Given different levels of constraint, it should be possible to
perform
>> bit-exact
>> >> verification testing all the way through encode and decode --
just like
>> standard
>> >> speech codecs.  I have a feeling this is one reason that audio
codecs >> 
other
>> than
>> >> MP3 may become the standard in AoIP / AoP systems in the
future, the way
>> certain
>> >> speech codecs are standard now.  Otherwise, it is difficult
for customers 
>> to
>> >> know what they are getting.  It also makes it difficult for
telecom >> 
vendors
>> to
>> >> provide reasonable assurance on indemnification issues.
>> >>
>> >> Jeff Brower
>> >> Signalogic
>> >>
>> >>
>> >> >HI Jeff,
>> >> >   When you buy CD from standard, in CD they give some
conformance
>> >> >streams. Your decoder should able to decode and final
output error
>> >> >should not exceed the error specified from reference file.
The exact
>> >> >procedure for testing of decoder using mp3 file is
specified in part4
>> >> >of standard (conformance testing).
>> >> >  For encoder only restriction is that the bitstream
should confirm
>> >> >the standard. The quality of encoded file depends on
Encoder
>> >> >implementation ( quantizor, psycho-acoustics etc). So
output encoded
>> >> >files of MP3 encoder are of different audio quality
depending on
>> >> >the encoder implemetation, But decoder will able to decode
all
>> >> >mp3 files. For high quality encoder, you have to pay more.
>> >> >Regards
>> >> >Mihir Mody
>> >> >Saken Communication technology Ltd
>> >> >
>> >> >
>> >> >
>> >> >On Mon, 19 Feb 2001, Jeff Brower wrote:
>> >> >
>> >> >> Mihir Narendra Mody-
>> >> >>
>> >> >> >  You can go to www.mpeg.org and its gives many
links to MP3 papers,
>> >> >> >software etc. You can buy standard from ISO site.
>> >> >>
>> >> >> One problem we have with calling the ISO site
"standard":  there are no
>> >> standard
>> >> >> input and output vectors to use for bit-exactness
verification.  I.e.
>> there
>> >> are
>> >> >> no given .wav (or .aif) input files, .mp3 output
files, and resulting
>> decoded
>> >> >> .wav files for comparison.
>> >> >>
>> >> >> We also tried to get comparison files from
Fraunhofer, even going so >> 
far
>> as
>> >> to
>> >> >> contact upper management.  Nothing.  Fraunhofer has
some .mp3 files on
>> their
>> >> >> site, but they appear to withhold the original .wav
files.
>> >> >>
>> >> >> So everyone's implementation of MP3 is possibly
-- likely at least
>> somewhat
>> >> --
>> >> >> different, as long as it sounds Ok?  I guess so.
>> >> >>
>> >> >> Any comments on this issue are greatly appreciated.
>> >> >>
>> >> >> Jeff Brower
>> >> >> DSP sw/hw engineer
>> >> >> Signalogic
	

Hello,

Mihir Narendra Mody wrote:
> 
> Hi,
>   I agree with you to some extent. What we found that when signal
> is nearly perceptually transpert, the ODG score is highly reliable.
> But when then score is above -1 or -2 it is not much reliable. But
> for high quality encoding the ODG has high correlation with SDG. Actully
> PEAQ standard discuuses all this issues and gives confindance levels,
> various graph for many reference signals.

Do we speak about the BASIC or the ADVANCED Model? 

Alexander

-- 
alexander lerch
lerch@lerc...

zplane.development
holsteinische str. 39-42
12161 berlin
 fon: +49.30.854 09 15.0
 fax: +49.30.854 09 15.5
	

Hi,
  So there is not baseline in case of MP3. Usually all people compare
quality of their encoder to FhG Encoder(supposed to be best) for stereo ,
128 kbs, 48 khz refence signal.
Regards,
Mihir Mody,
Sasken Communication Technology Ltd.
Bangalore - INDIA
	On Tue, 20 Feb 2001, Jeff Brower wrote:

> Mihir Narendra Mody-
>
> >So differnt manufacture
> >can come up with differnt implementation and quality of encoding is
> >differnt. The more knowlege and experiments done by manufactures will
> >give better quality.
>
> So where is the baseline?  Where is the minimum level, testable by an
> independently sponsored and impartial testing organization?  Such a test
must be
> developed for MP3 (and/or other audio codecs) before they can be used in
telecom
> and carrier class products.  The closest telecom analogy seems to be echo
> cancellers, which also are improved constantly by different manufacturers. 
But
> -- for echo cancellers there is a widely accepted performance standard
(G.165,
> G.168).  I guess MP3 is just not there yet.
>
> Thanks very much for discussion.  I think I understand the problem better
now.
>
> Jeff Brower
> DSP sw/hw engineer
> Signalogic
>
>
> On Tue, 20 Feb 2001, Mihir Narendra Mody <mihir@mihi...> wrote:
> >Hi Jeff,
> >   In Mp3 standard, the decoder is standard and no much space is left
> >for differernt manufacture to change it. Only they can use fast
algorithm
> >and resulting some error should not exceed specified value in standard.
> >   The real thing or chanllenge they kept on encoder. The algorithm
> >is not standardised but bitstream is standardized. So differnt
manufacture
> >can come up with differnt implementation and quality of encoding is
> >differnt. The more knowlege and experiments done by manufactures will
> >give better quality. For better quality you have to pay more. There are
> >some reference wave files (like castanet, germal male speech) are there
> >in audio coding. All manufacture have to specify the quality (MOS
score)
> >of this refence file by their encoder. There are some special softeare
> >also
> >avaible (like OPERA from OPTICOM) which will give quality of encoded
> >files. So while buuying you can ask the qulity of encoder on this
> >benchmark signals.
> > I hope this will clarify your doubt
> >Regards
> >Mihir N Mody
> >Sasken Communication Techology Ltd
> >Bangalore, INDIA
> >
> >
> >
> >On Mon, 19 Feb 2001, Jeff Brower wrote:
> >
> >> Mihir Narendra Mody-
> >>
> >> Thanks for your informative reply.  It's more than I thought
was there, but
> >> still too imprecise.  There should also be conformance streams for
the
> encoder,
> >> given certain parameters.
> >>
> >> Given different levels of constraint, it should be possible to
perform
> bit-exact
> >> verification testing all the way through encode and decode -- just
like
> standard
> >> speech codecs.  I have a feeling this is one reason that audio
codecs other
> than
> >> MP3 may become the standard in AoIP / AoP systems in the future,
the way
> certain
> >> speech codecs are standard now.  Otherwise, it is difficult for
customers to
> >> know what they are getting.  It also makes it difficult for
telecom vendors
> to
> >> provide reasonable assurance on indemnification issues.
> >>
> >> Jeff Brower
> >> Signalogic
> >>
> >>
> >> >HI Jeff,
> >> >   When you buy CD from standard, in CD they give some
conformance
> >> >streams. Your decoder should able to decode and final output
error
> >> >should not exceed the error specified from reference file. The
exact
> >> >procedure for testing of decoder using mp3 file is specified
in part4
> >> >of standard (conformance testing).
> >> >  For encoder only restriction is that the bitstream should
confirm
> >> >the standard. The quality of encoded file depends on Encoder
> >> >implementation ( quantizor, psycho-acoustics etc). So output
encoded
> >> >files of MP3 encoder are of different audio quality depending
on
> >> >the encoder implemetation, But decoder will able to decode all
> >> >mp3 files. For high quality encoder, you have to pay more.
> >> >Regards
> >> >Mihir Mody
> >> >Saken Communication technology Ltd
> >> >
> >> >
> >> >
> >> >On Mon, 19 Feb 2001, Jeff Brower wrote:
> >> >
> >> >> Mihir Narendra Mody-
> >> >>
> >> >> >  You can go to www.mpeg.org and its gives many links
to MP3 papers,
> >> >> >software etc. You can buy standard from ISO site.
> >> >>
> >> >> One problem we have with calling the ISO site
"standard":  there are no
> >> standard
> >> >> input and output vectors to use for bit-exactness
verification.  I.e.
> there
> >> are
> >> >> no given .wav (or .aif) input files, .mp3 output files,
and resulting
> decoded
> >> >> .wav files for comparison.
> >> >>
> >> >> We also tried to get comparison files from Fraunhofer,
even going so far
> as
> >> to
> >> >> contact upper management.  Nothing.  Fraunhofer has some
.mp3 files on
> their
> >> >> site, but they appear to withhold the original .wav
files.
> >> >>
> >> >> So everyone's implementation of MP3 is possibly --
likely at least
> somewhat
> >> --
> >> >> different, as long as it sounds Ok?  I guess so.
> >> >>
> >> >> Any comments on this issue are greatly appreciated.
> >> >>
> >> >> Jeff Brower
> >> >> DSP sw/hw engineer
> >> >> Signalogic
>
>
>
> _____________________________________
> Note: If you do a simple "reply" with your email client, only the
author of this message will receive your answer.  You need to do a "reply
all" if you want your answer to be distributed to the entire group.
>
> _____________________________________
> About this discussion group:
>
> To Join:  audiodsp-subscribe@audi...
>
> To Post:  audiodsp@audi...
>
> To Leave: audiodsp-unsubscribe@audi...
>
> Archives: http://www.egroups.com/group/audiodsp
>
> Other DSP-Related Groups: http://www.dsprelated.com
>
>
	

Hi,
  I agree with you to some extent. What we found that when signal
is nearly perceptually transpert, the ODG score is highly reliable.
But when then score is above -1 or -2 it is not much reliable. But
for high quality encoding the ODG has high correlation with SDG. Actully
PEAQ standard discuuses all this issues and gives confindance levels,
various graph for many reference signals.
Regards,
Mihir Mody
Sasken Communication Technology Ltd.
Bangalore - INDIA
	On Tue, 20 Feb 2001, alexander lerch wrote:

> Hello Mihir Narendra Mody,
>
> Mihir Narendra Mody wrote:
> >
> > There are some special softeare
> > also
> > avaible (like OPERA from OPTICOM) which will give quality of encoded
> > files. So while buuying you can ask the qulity of encoder on this
> > benchmark signals.
>
> I spent some time with implementing PEAQ (ITU-R BS.1387),
> which is the application in OPERA to rate high quality codecs,
> and I can say it will not supersede listening tests. The
> correlation of PEAQ ratings with results of listening tests is
> not very high.
> Also, PEAQ is only designed for high quality audio codecs, and
> codecs with middle quality can not be evaluated. For low
> quality there are only some speech quality measurement tools
> (PSQM is integrated in OPERA, I think).
> In particular applications, objective measurement tools make
> sense, but the rating of some encoded-decoded audio files will
> not be very useful for quality evaluation of the codec.
>
> Regards,
> Alexander
>
> --
> alexander lerch
> lerch@lerc...
>
> zplane.development
> holsteinische str. 39-42
> 12161 berlin
>  fon: +49.30.854 09 15.0
>  fax: +49.30.854 09 15.5
>
	

Mihir Narendra Mody-

>So differnt manufacture
>can come up with differnt implementation and quality of encoding is
>differnt. The more knowlege and experiments done by manufactures will
>give better quality.

So where is the baseline?  Where is the minimum level, testable by an 
independently sponsored and impartial testing organization?  Such a test must be

developed for MP3 (and/or other audio codecs) before they can be used in telecom

and carrier class products.  The closest telecom analogy seems to be echo 
cancellers, which also are improved constantly by different manufacturers.  But 
-- for echo cancellers there is a widely accepted performance standard (G.165, 
G.168).  I guess MP3 is just not there yet.

Thanks very much for discussion.  I think I understand the problem better now.

Jeff Brower
DSP sw/hw engineer
Signalogic
	On Tue, 20 Feb 2001, Mihir Narendra Mody <mihir@mihi...> wrote:
>Hi Jeff,
>   In Mp3 standard, the decoder is standard and no much space is left
>for differernt manufacture to change it. Only they can use fast algorithm
>and resulting some error should not exceed specified value in standard.
>   The real thing or chanllenge they kept on encoder. The algorithm
>is not standardised but bitstream is standardized. So differnt manufacture
>can come up with differnt implementation and quality of encoding is
>differnt. The more knowlege and experiments done by manufactures will
>give better quality. For better quality you have to pay more. There are
>some reference wave files (like castanet, germal male speech) are there
>in audio coding. All manufacture have to specify the quality (MOS score)
>of this refence file by their encoder. There are some special softeare
>also
>avaible (like OPERA from OPTICOM) which will give quality of encoded
>files. So while buuying you can ask the qulity of encoder on this
>benchmark signals.
> I hope this will clarify your doubt
>Regards
>Mihir N Mody
>Sasken Communication Techology Ltd
>Bangalore, INDIA
>
>
>
>On Mon, 19 Feb 2001, Jeff Brower wrote:
>
>> Mihir Narendra Mody-
>>
>> Thanks for your informative reply.  It's more than I thought was
there, but
>> still too imprecise.  There should also be conformance streams for the 
encoder,
>> given certain parameters.
>>
>> Given different levels of constraint, it should be possible to perform 
bit-exact
>> verification testing all the way through
encode and decode -- just like 
standard
>> speech codecs.  I have a feeling this is one
reason that audio codecs other 
than
>> MP3 may become the standard in AoIP / AoP
systems in the future, the way 
certain
>> speech codecs are standard now.  Otherwise, it
is difficult for customers to
>> know what they are getting.  It also makes it difficult for telecom
vendors 
to
>> provide reasonable assurance on
indemnification issues.
>>
>> Jeff Brower
>> Signalogic
>>
>>
>> >HI Jeff,
>> >   When you buy CD from standard, in CD they give some conformance
>> >streams. Your decoder should able to decode and final output error
>> >should not exceed the error specified from reference file. The
exact
>> >procedure for testing of decoder using mp3 file is specified in
part4
>> >of standard (conformance testing).
>> >  For encoder only restriction is that the bitstream should confirm
>> >the standard. The quality of encoded file depends on Encoder
>> >implementation ( quantizor, psycho-acoustics etc). So output
encoded
>> >files of MP3 encoder are of different audio quality depending on
>> >the encoder implemetation, But decoder will able to decode all
>> >mp3 files. For high quality encoder, you have to pay more.
>> >Regards
>> >Mihir Mody
>> >Saken Communication technology Ltd
>> >
>> >
>> >
>> >On Mon, 19 Feb 2001, Jeff Brower wrote:
>> >
>> >> Mihir Narendra Mody-
>> >>
>> >> >  You can go to www.mpeg.org and its gives many links to
MP3 papers,
>> >> >software etc. You can buy standard from ISO site.
>> >>
>> >> One problem we have with calling the ISO site
"standard":  there are no
>> standard
>> >> input and output vectors to use for bit-exactness
verification.  I.e. 
there
>> are
>> >> no given .wav (or .aif) input files, .mp3 output files, and
resulting 
decoded
>> >> .wav files for comparison.
>> >>
>> >> We also tried to get comparison files from Fraunhofer, even
going so far 
as
>> to
>> >> contact upper management.  Nothing.  Fraunhofer has some .mp3
files on 
their
>> >> site, but they appear to withhold the
original .wav files.
>> >>
>> >> So everyone's implementation of MP3 is possibly -- likely
at least 
somewhat
>> --
>> >> different, as long as it sounds Ok?  I guess so.
>> >>
>> >> Any comments on this issue are greatly appreciated.
>> >>
>> >> Jeff Brower
>> >> DSP sw/hw engineer
>> >> Signalogic
	

Hello Mihir Narendra Mody,

Mihir Narendra Mody wrote:
> 
> There are some special softeare
> also
> avaible (like OPERA from OPTICOM) which will give quality of encoded
> files. So while buuying you can ask the qulity of encoder on this
> benchmark signals.

I spent some time with implementing PEAQ (ITU-R BS.1387),
which is the application in OPERA to rate high quality codecs,
and I can say it will not supersede listening tests. The
correlation of PEAQ ratings with results of listening tests is
not very high. 
Also, PEAQ is only designed for high quality audio codecs, and
codecs with middle quality can not be evaluated. For low
quality there are only some speech quality measurement tools
(PSQM is integrated in OPERA, I think).
In particular applications, objective measurement tools make
sense, but the rating of some encoded-decoded audio files will
not be very useful for quality evaluation of the codec.

Regards,
Alexander

-- 
alexander lerch
lerch@lerc...

zplane.development
holsteinische str. 39-42
12161 berlin
 fon: +49.30.854 09 15.0
 fax: +49.30.854 09 15.5
	

Hi Jeff,
   In Mp3 standard, the decoder is standard and no much space is left
for differernt manufacture to change it. Only they can use fast algorithm
and resulting some error should not exceed specified value in standard.
   The real thing or chanllenge they kept on encoder. The algorithm
is not standardised but bitstream is standardized. So differnt manufacture
can come up with differnt implementation and quality of encoding is
differnt. The more knowlege and experiments done by manufactures will
give better quality. For better quality you have to pay more. There are
some reference wave files (like castanet, germal male speech) are there
in audio coding. All manufacture have to specify the quality (MOS score)
of this refence file by their encoder. There are some special softeare
also
avaible (like OPERA from OPTICOM) which will give quality of encoded
files. So while buuying you can ask the qulity of encoder on this
benchmark signals.
 I hope this will clarify your doubt
Regards
Mihir N Mody
Sasken Communication Techology Ltd
Bangalore, INDIA
	On Mon, 19 Feb 2001, Jeff Brower wrote:

> Mihir Narendra Mody-
>
> Thanks for your informative reply.  It's more than I thought was
there, but
> still too imprecise.  There should also be conformance streams for the
encoder,
> given certain parameters.
>
> Given different levels of constraint, it should be possible to perform
bit-exact
> verification testing all the way through encode and decode -- just like
standard
> speech codecs.  I have a feeling this is one reason that audio codecs other
than
> MP3 may become the standard in AoIP / AoP systems in the future, the way
certain
> speech codecs are standard now.  Otherwise, it is difficult for customers
to
> know what they are getting.  It also makes it difficult for telecom vendors
to
> provide reasonable assurance on indemnification issues.
>
> Jeff Brower
> Signalogic
>
>
> >HI Jeff,
> >   When you buy CD from standard, in CD they give some conformance
> >streams. Your decoder should able to decode and final output error
> >should not exceed the error specified from reference file. The exact
> >procedure for testing of decoder using mp3 file is specified in part4
> >of standard (conformance testing).
> >  For encoder only restriction is that the bitstream should confirm
> >the standard. The quality of encoded file depends on Encoder
> >implementation ( quantizor, psycho-acoustics etc). So output encoded
> >files of MP3 encoder are of different audio quality depending on
> >the encoder implemetation, But decoder will able to decode all
> >mp3 files. For high quality encoder, you have to pay more.
> >Regards
> >Mihir Mody
> >Saken Communication technology Ltd
> >
> >
> >
> >On Mon, 19 Feb 2001, Jeff Brower wrote:
> >
> >> Mihir Narendra Mody-
> >>
> >> >  You can go to www.mpeg.org and its gives many links to MP3
papers,
> >> >software etc. You can buy standard from ISO site.
> >>
> >> One problem we have with calling the ISO site
"standard":  there are no
> standard
> >> input and output vectors to use for bit-exactness verification. 
I.e. there
> are
> >> no given .wav (or .aif) input files, .mp3 output files, and
resulting decoded
> >> .wav files for comparison.
> >>
> >> We also tried to get comparison files from Fraunhofer, even going
so far as
> to
> >> contact upper management.  Nothing.  Fraunhofer has some .mp3
files on their
> >> site, but they appear to withhold the original .wav files.
> >>
> >> So everyone's implementation of MP3 is possibly -- likely at
least somewhat
> --
> >> different, as long as it sounds Ok?  I guess so.
> >>
> >> Any comments on this issue are greatly appreciated.
> >>
> >> Jeff Brower
> >> DSP sw/hw engineer
> >> Signalogic
>
	

Mihir Narendra Mody-

Thanks for your informative reply.  It's more than I thought was there, but

still too imprecise.  There should also be conformance streams for the encoder, 
given certain parameters.

Given different levels of constraint, it should be possible to perform bit-exact

verification testing all the way through encode and decode -- just like standard

speech codecs.  I have a feeling this is one reason that audio codecs other than

MP3 may become the standard in AoIP / AoP systems in the future, the way certain

speech codecs are standard now.  Otherwise, it is difficult for customers to 
know what they are getting.  It also makes it difficult for telecom vendors to 
provide reasonable assurance on indemnification issues.

Jeff Brower
Signalogic
	>HI Jeff,
>   When you buy CD from standard, in CD they give
some conformance
>streams. Your decoder should able to decode and final output error
>should not exceed the error specified from reference file. The exact
>procedure for testing of decoder using mp3 file is specified in part4
>of standard (conformance testing).
>  For encoder only restriction is that the bitstream should confirm
>the standard. The quality of encoded file depends on Encoder
>implementation ( quantizor, psycho-acoustics etc). So output encoded
>files of MP3 encoder are of different audio quality depending on
>the encoder implemetation, But decoder will able to decode all
>mp3 files. For high quality encoder, you have to pay more.
>Regards
>Mihir Mody
>Saken Communication technology Ltd
>
>
>
>On Mon, 19 Feb 2001, Jeff Brower wrote:
>
>> Mihir Narendra Mody-
>>
>> >  You can go to www.mpeg.org and its gives many links to MP3
papers,
>> >software etc. You can buy standard from ISO site.
>>
>> One problem we have with calling the ISO site "standard": 
there are no 
standard
>> input and output vectors to use for
bit-exactness verification.  I.e. there 
are
>> no given .wav (or .aif) input files, .mp3
output files, and resulting decoded
>> .wav files for comparison.
>>
>> We also tried to get comparison files from Fraunhofer, even going so
far as 
to
>> contact upper management.  Nothing. 
Fraunhofer has some .mp3 files on their
>> site, but they appear to withhold the original .wav files.
>>
>> So everyone's implementation of MP3 is possibly -- likely at least
somewhat 
--
>> different, as long as it sounds Ok?  I guess
so.
>>
>> Any comments on this issue are greatly appreciated.
>>
>> Jeff Brower
>> DSP sw/hw engineer
>> Signalogic