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Hi

Where can I find Mp3 compression algorithms ?

Ben
	

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Hi!

"Jacobs, Ben" wrote:

>                 > Where can I find Mp3 compression algorithms ?
> 
>                 What do you are looking for: information or source code?
> 
>                 Alexander
> 
>                 I want to understand the compression technique in detail,
> but also apply it. Thus both info and source code will be welcome.
> 
>                 Ben

For understanding, you can find some papers and information at
the official MPEG homepage
http://www.tnt.uni-hannover.de/project/mpeg/audio/
and
http://www.mp3-tech.org

For source code, the lame project should be most interesting,
I'm not sure if the links are correct:
http://www.mp3dev.org
http://www.sulaco.org/mp3

Hope this helps somewhat,
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
	

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Hi,
  You can go to www.mpeg.org and its gives many links to MP3 papers,
software etc. You can buy standard from ISO site.
Regards
Mihir Mody
	On Fri, 16 Feb 2001, Jacobs, Ben wrote:

> Hi
>
> Where can I find Mp3 compression algorithms ?
>
> Ben
>
>
>
> _____________________________________
> 
>
>
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
>
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

Hello Jeff Brower,

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.

In this case, it wouldn't be possible to improve such codecs
in quality. This would be not very good, since all first
generation audio codecs only provided a quite bad quality (see
mp3). 
But, of course, this way you have no guarantee about the audio
quality.

> 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.

Do you mean the audio quality? How to get an objective measure
of quality (for the court case)?

BTW, which codec do you mean by "other than mp3"? For all MPEG
Encoders (mp2, mp3, aac, etc.) only the bitstream is defined,
and some newer codecs like OggVorbis do it in the same way. I
don't know exactly, but I think even the proprietary codecs
like ATRAC, AC-3, DTS, etc. do not specify a bit-exact
description of the encoded bitstream.

Regards,
Alexander Lerch

-- 
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
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
>
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.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
>
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
>
>
>
> _____________________________________
> 
>
>
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
	

(You need to be a member of audiodsp -- send a blank email to audiodsp-subscribe@yahoogroups.com )

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
	

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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
>
	

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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
>
>
>
> _____________________________________
> 
>
>
> 
>
>
	

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