Science > Physics > How can I tell music has been an MP3? Quantitative Measurement of Fidelity
| Topic: |
Science > Physics |
| User: |
"Dave" |
| Date: |
22 Jun 2007 05:18:52 PM |
| Object: |
How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
I have been disappointed with the audio quality of some CDs I have
bought recently. Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
.
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| User: "Richard Crowley" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
22 Jun 2007 05:54:03 PM |
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"Dave" wrote ...
I have been disappointed with the audio quality of some CDs I have
bought recently.
This has been discussed many times in the recent past.
Note that far and away the prime suspect is hyper-compression
(compression of the audio levels, NOT data compression of the
signal stream.)
Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
1) SNR is not "an accepted measurement of fidelity"
2) There is no specific "accepted measurement of fidelity"
"Fidelity" is a combination of many things. Some subjective.
3) It would be difficult-to-impossible to actually meausre SNR
on a commercial CD because of the way they are mastered.
(i.e. there is no "baseline" because it is usually muted)
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
Did you buy these CDs from the back of Guido's white van?
Do you know they are legitimate and not pirated copies?
Seems very unlikely that commercial CDs would have ever been
processed through any such gross lossy step as MP3 compression.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
It has been discussed here before that there are relatively easy ways
of analyzing audio to detect lossy compression such as MP3. Many
people claim they can hear it easily.
.
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| User: "Dave" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
22 Jun 2007 08:58:27 PM |
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On 22 Jun, 23:54, "Richard Crowley" <rcrow...@xp7rt.net> wrote:
"Dave" wrote ...
I have been disappointed with the audio quality of some CDs I have
bought recently.
This has been discussed many times in the recent past.
Note that far and away the prime suspect is hyper-compression
(compression of the audio levels, NOT data compression of the
signal stream.)
Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
1) SNR is not "an accepted measurement of fidelity"
2) There is no specific "accepted measurement of fidelity"
"Fidelity" is a combination of many things. Some subjective.
3) It would be difficult-to-impossible to actually meausre SNR
on a commercial CD because of the way they are mastered.
(i.e. there is no "baseline" because it is usually muted)
Have there been no bright PhD students sponsored by the music
industry, or are they too busy with their revenue stream? The noise
is what is not the notes. For a symphony you have an idea of what the
notes should be, because you have the sheet music, and you know what a
violin, flute etc should sound like. You may be able to measure
something more because that is what the brain does.
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
Did you buy these CDs from the back of Guido's white van?
Do you know they are legitimate and not pirated copies?
Seems very unlikely that commercial CDs would have ever been
processed through any such gross lossy step as MP3 compression.
Business takes the route of maximum profit.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
It has been discussed here before that there are relatively easy ways
of analyzing audio to detect lossy compression such as MP3. Many
people claim they can hear it easily.
The method I saw was looking for high frequency cut off. Is this was
you were thinking of?
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| User: "Richard Crowley" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
22 Jun 2007 09:43:11 PM |
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"Dave" wrote ...
, "Richard Crowley" wrote:
1) SNR is not "an accepted measurement of fidelity"
2) There is no specific "accepted measurement of fidelity"
"Fidelity" is a combination of many things. Some subjective.
3) It would be difficult-to-impossible to actually meausre SNR
on a commercial CD because of the way they are mastered.
(i.e. there is no "baseline" because it is usually muted)
Have there been no bright PhD students sponsored by the music
industry, or are they too busy with their revenue stream? The noise
is what is not the notes. For a symphony you have an idea of what the
notes should be, because you have the sheet music, and you know what a
violin, flute etc should sound like. You may be able to measure
something more because that is what the brain does.
That is just impossibly simplistic. There is a great deal of stuff
"between the notes" besides noise. Have you done much
recording yourself?
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
Did you buy these CDs from the back of Guido's white van?
Do you know they are legitimate and not pirated copies?
Seems very unlikely that commercial CDs would have ever been
processed through any such gross lossy step as MP3 compression.
Business takes the route of maximum profit.
If you dont' want to reveal any clues that would help answer
your question, its up to you.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
It has been discussed here before that there are relatively easy ways
of analyzing audio to detect lossy compression such as MP3. Many
people claim they can hear it easily.
The method I saw was looking for high frequency cut off. Is this was
you were thinking of?
No, there are supposed to be other "markers" of MP3-style compression.
But I didn't pay attention to what they were or how to find them because I'm
not particularly concerned. I use MP3 only as a last-step release format.
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| User: "Scott Dorsey" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
26 Jun 2007 08:54:24 AM |
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"Dave" wrote ...
Have there been no bright PhD students sponsored by the music
industry, or are they too busy with their revenue stream? The noise
is what is not the notes. For a symphony you have an idea of what the
notes should be, because you have the sheet music, and you know what a
violin, flute etc should sound like. You may be able to measure
something more because that is what the brain does.
"Music is the space between the notes."
-- Franz Liszt
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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| User: "Richard Kuschel" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
26 Jun 2007 01:20:17 PM |
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On Jun 26, 7:54 am, (Scott Dorsey) wrote:
"Dave" wrote ...
Have there been no bright PhD students sponsored by the music
industry, or are they too busy with their revenue stream? The noise
is what is not the notes. For a symphony you have an idea of what the
notes should be, because you have the sheet music, and you know what a
violin, flute etc should sound like. You may be able to measure
something more because that is what the brain does.
"Music is the space between the notes."
-- Franz Liszt
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
I thought that "Music is the space between the notes." was John Cage,
but more research seems to attribute it to Claude Debussy. I would
imagine that it has been paraphrased a few times by other people.
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| User: "Dave" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 03:32:20 AM |
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On 23 Jun, 03:43, "Richard Crowley" <rcrow...@xp7rt.net> wrote:
"Dave" wrote ...
, "Richard Crowley" wrote:
1) SNR is not "an accepted measurement of fidelity"
2) There is no specific "accepted measurement of fidelity"
"Fidelity" is a combination of many things. Some subjective.
3) It would be difficult-to-impossible to actually meausre SNR
on a commercial CD because of the way they are mastered.
(i.e. there is no "baseline" because it is usually muted)
Have there been no bright PhD students sponsored by the music
industry, or are they too busy with their revenue stream? The noise
is what is not the notes. For a symphony you have an idea of what the
notes should be, because you have the sheet music, and you know what a
violin, flute etc should sound like. You may be able to measure
something more because that is what the brain does.
That is just impossibly simplistic. There is a great deal of stuff
"between the notes" besides noise. Have you done much
recording yourself?
It doesn't sound as complicated as fusion, and that is having billions
spent on it. Besides I thought banks and defence liked graduates with
in-depth signal analysis experience.
I have listened to plenty of CD (about 650), so I think I can tell a
good recording from a bad one. There may be problems of course with
quantative measurement, in that the recording could be done to get the
measurement
high, and it could just sound clinical.
The point was that if I thought a CD sounded poor quality I think
there should be a computer program to confirm this, instead of just
asking someone else.
.
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| User: "Serge Auckland" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 04:19:00 AM |
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"Dave" <dwickford@yahoo.com> wrote in message
news:1182587540.353891.294130@q69g2000hsb.googlegroups.com...
Snipped
I have listened to plenty of CD (about 650), so I think I can tell a
good recording from a bad one. There may be problems of course with
quantative measurement, in that the recording could be done to get the
measurement
high, and it could just sound clinical.
The point was that if I thought a CD sounded poor quality I think
there should be a computer program to confirm this, instead of just
asking someone else.
That's like asking if there's a computer program to confirm a wine is of
poor quality, or a piece of art work is of poor quality. Quality is
subjective, is a composite of many individual factors and can't be reduced
to a number. A computer program (or manual instruments) can analyse the
performance of a piece of music, and give you numbers for dynamic range,
frequency range and by analysing the gaps between music, the background
noise level. It can't then tell you whether this is "good" or "bad" as these
are value judgements.
As to your OP, I think you are asking for a piece of (free) software that
will analyse for any "footprint" left behind by MP3 compression. I have
never come across any such software, free or otherwise, nor do I know of any
reliable way of telling subjectively that something has been (or even is)
MP3 processed, if the bit rate used is high enough.
Others have mentioned the infuriating habit today of removing any vestige of
dynamic range from modern mastered CDs, then clipping the result, all in an
attempt to get maximum loudness. I previously posted that the Daily Mail
even, ran an article a week or two ago highlighting this trend. However, it
is not all the fault of the producers foisting their ideas on the poor
artists, even some artists insist that their CDs are mastered as loud as
possible, as a part of their "sound". Lily Allen was mentioned by name.
This, I think, is much more likely to be the reason for dissatisfaction with
recently mastered CDs than any (unlikely) possibility that MP3 was involved.
As a consequence, I now don't buy any CD that was mastered (or remastered)
in the past 10-12 years.
S.
--
http://audiopages.googlepages.com
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| User: "Paul Stamler" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 04:33:12 AM |
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"Serge Auckland" <serge.auckland@tiscali.co.uk> wrote in message
news:eYadnZYnYu8beOHbnZ2dnUVZ8saonZ2d@bt.com...
As to your OP, I think you are asking for a piece of (free) software that
will analyse for any "footprint" left behind by MP3 compression. I have
never come across any such software, free or otherwise
Well, you could look for a 15.8kHz hard bandlimit on the audio using the
frequency analyzer in a DAW. That would indicate the likelihood that a
128kbps .mp3 was part of the chain. It's still pretty unlikely, though,
unless the recording is something like a live gig issued by the band itself,
perhaps from a portable .mp3 recorder.
Not impossible, though. Hey, I once co-produced and mastered an album from a
hodgepodge of sources, and one track on it was from MiniDisc, which uses
perceptual-coding algorithms not too conceptually different from those in
the .mp3 format. It's Art Thieme's "The Older I Get, The Better I Was" on
Waterbug. I'd be surprised if someone can tell me which track it was by ear
(no cheating and looking at the liner notes!)
Peace,
Paul
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| User: "Serge Auckland" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 07:33:58 AM |
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"Paul Stamler" <pstamlerhell@pobox.com> wrote in message
news:sN5fi.112406$Sa4.16757@bgtnsc05-news.ops.worldnet.att.net...
"Serge Auckland" <serge.auckland@tiscali.co.uk> wrote in message
news:eYadnZYnYu8beOHbnZ2dnUVZ8saonZ2d@bt.com...
As to your OP, I think you are asking for a piece of (free) software that
will analyse for any "footprint" left behind by MP3 compression. I have
never come across any such software, free or otherwise
Well, you could look for a 15.8kHz hard bandlimit on the audio using the
frequency analyzer in a DAW. That would indicate the likelihood that a
128kbps .mp3 was part of the chain. It's still pretty unlikely, though,
unless the recording is something like a live gig issued by the band
itself,
perhaps from a portable .mp3 recorder.
A hard bandlimit may indicate the possibility of a 128k MP3, but
band-limiting can indicate also that a lower sample rate was used:- 32k
sample rate was regularly used in the past for ISDN audio transfers, if the
intended outlet was FM transmission. Higher bit-rate MP3 would not
necessarily have the band-limiting except the normal anti-aliasing filter
common to all PCM digital audio.
Not impossible, though. Hey, I once co-produced and mastered an album from
a
hodgepodge of sources, and one track on it was from MiniDisc, which uses
perceptual-coding algorithms not too conceptually different from those in
the .mp3 format. It's Art Thieme's "The Older I Get, The Better I Was" on
Waterbug. I'd be surprised if someone can tell me which track it was by
ear
(no cheating and looking at the liner notes!)
Peace,
Paul
And some albums were recorded on Tascam Portastudios (4 track analogue
cassette), which, arguably, sound a lot worse than MP3 at higher bit rates,
domestic reel-reel machines and other sources.
S
http://audiopages.googlepages.com
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| User: "Keith G" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 06:27:18 AM |
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"Serge Auckland" <serge.auckland@tiscali.co.uk> wrote in message
news:eYadnZYnYu8beOHbnZ2dnUVZ8saonZ2d@bt.com...
"Dave" <dwickford@yahoo.com> wrote
The point was that if I thought a CD sounded poor quality I think
there should be a computer program to confirm this, instead of just
asking someone else.
That's like asking if there's a computer program to confirm a wine is
of poor quality, or a piece of art work is of poor quality. Quality is
subjective, is a composite of many individual factors and can't be
reduced to a number. A computer program (or manual instruments) can
analyse the performance of a piece of music, and give you numbers for
dynamic range, frequency range and by analysing the gaps between
music, the background noise level. It can't then tell you whether this
is "good" or "bad" as these are value judgements.
The clue to the answer to this sort of question is usually in the
question itself. Plenty of people seem need to see figures or a graph to
answer the 'am I enjoying/did I enjoy that?' question - there's no
shortage of that in here....
Me? I wouldn't be without the Deviation Meter on me chooner - otherwise,
how TF would I know if the music was sounding any good (or not)..??
;-)
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| User: "Scott Dorsey" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
26 Jun 2007 08:57:58 AM |
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Serge Auckland <serge.auckland@tiscali.co.uk> wrote:
That's like asking if there's a computer program to confirm a wine is of
poor quality, or a piece of art work is of poor quality.
Precisely, and if you could do such a thing effectively in a way that would
correlate with human judgement, you could probably get a Turing award if
not a Nobel.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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| User: "tony sayer" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 02:49:55 PM |
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In article <1182587540.353891.294130@q69g2000hsb.googlegroups.com>, Dave
<dwickford@yahoo.com> writes
On 23 Jun, 03:43, "Richard Crowley" <rcrow...@xp7rt.net> wrote:
"Dave" wrote ...
, "Richard Crowley" wrote:
1) SNR is not "an accepted measurement of fidelity"
2) There is no specific "accepted measurement of fidelity"
"Fidelity" is a combination of many things. Some subjective.
3) It would be difficult-to-impossible to actually meausre SNR
on a commercial CD because of the way they are mastered.
(i.e. there is no "baseline" because it is usually muted)
Have there been no bright PhD students sponsored by the music
industry, or are they too busy with their revenue stream? The noise
is what is not the notes. For a symphony you have an idea of what the
notes should be, because you have the sheet music, and you know what a
violin, flute etc should sound like. You may be able to measure
something more because that is what the brain does.
That is just impossibly simplistic. There is a great deal of stuff
"between the notes" besides noise. Have you done much
recording yourself?
It doesn't sound as complicated as fusion, and that is having billions
spent on it. Besides I thought banks and defence liked graduates with
in-depth signal analysis experience.
I have listened to plenty of CD (about 650), so I think I can tell a
good recording from a bad one. There may be problems of course with
quantative measurement, in that the recording could be done to get the
measurement
high, and it could just sound clinical.
The point was that if I thought a CD sounded poor quality I think
there should be a computer program to confirm this, instead of just
asking someone else.
Oddly enough I've been out an about to some live events recently and the
sound there and at home ..I always want to twiddle something to make it
sound how I think it should be rather then what it is;)
--
Tony Sayer
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| User: "Ty Ford" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 07:20:33 AM |
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On Fri, 22 Jun 2007 21:58:27 -0400, Dave wrote
(in article <1182563907.521869.41060@n60g2000hse.googlegroups.com>):
I have been disappointed with the audio quality of some CDs I have
bought recently.
This has been discussed many times in the recent past.
Note that far and away the prime suspect is hyper-compression
(compression of the audio levels, NOT data compression of the
signal stream.)
On the indie market, it's also because the recording talent too frequently
can't tell the difference between "Ouch" and "Nice."
Cheap mic and preamp choices and not understanding how good audio is made has
been as devastating to the quality of audio. You need good people who can
make better choices.
That's the downside to the democratization of the technology. When ANYONE can
afford to do it, that's what you get.
I now shoot and edit video for a part of my living. I'm sure some DPs would
scorn my work. That's fine. I'm learning and I'll get better.
Gotta' nice handheld piece shot last week for singer/songwriter friend
Randall Williams. He saw mine and wanted something up on YouTube.
You can see/hear it at:
http://www.youtube.com/watch?v=sDjKgmMydF4
Regards,
Ty Ford
--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=4RZJ9MptZmU
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| User: "Dave Plowman News" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 11:27:06 AM |
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In article <8ZKdnUzsG7CMjeDbnZ2dnUVZ_h7inZ2d@comcast.com>,
Ty Ford <tyreeford@comcast.net> wrote:
Gotta' nice handheld piece shot last week for singer/songwriter friend
Randall Williams. He saw mine and wanted something up on YouTube.
You can see/hear it at:
http://www.youtube.com/watch?v=sDjKgmMydF4
'Nice' hand held? To me, hand held means slight movement to simulate what
the eye sees. Yours appears to be moving the camera for the sake of it. I
was taught any camera moves that grab the eye are bad moves - it suggests
the subject material is too boring on its own. Of course such techniques
are all too common these days and obviously loved by meja types who have
no interest in presenting a subject intelligently.
--
*(on a baby-size shirt) "Party -- my crib -- two a.m
Dave Plowman London SW
To e-mail, change noise into sound.
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| User: "Ty Ford" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
24 Jun 2007 08:24:48 AM |
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On Sat, 23 Jun 2007 12:27:06 -0400, Dave Plowman (News) wrote
(in article <4ef78a42c9dave@davenoise.co.uk>):
In article <8ZKdnUzsG7CMjeDbnZ2dnUVZ_h7inZ2d@comcast.com>,
Ty Ford <tyreeford@comcast.net> wrote:
Gotta' nice handheld piece shot last week for singer/songwriter friend
Randall Williams. He saw mine and wanted something up on YouTube.
You can see/hear it at:
http://www.youtube.com/watch?v=sDjKgmMydF4
'Nice' hand held? To me, hand held means slight movement to simulate what
the eye sees. Yours appears to be moving the camera for the sake of it. I
was taught any camera moves that grab the eye are bad moves - it suggests
the subject material is too boring on its own. Of course such techniques
are all too common these days and obviously loved by meja types who have
no interest in presenting a subject intelligently.
"All too common" , I'll take that from anyone in the UK. :)
Thanks,
Ty Ford
--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=4RZJ9MptZmU
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| User: "Markus Mietling" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 09:18:52 AM |
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Ty Ford wrote in <8ZKdnUzsG7CMjeDbnZ2dnUVZ_h7inZ2d@comcast.com>:
On the indie market, it's also because the recording talent too frequently
can't tell the difference between "Ouch" and "Nice."
Funny you should say that ...
I now shoot and edit video for a part of my living.
Gotta' nice handheld piece shot last week
This isn't what I'd call "nice," really not. I didn't sit through the
whole piece though, because your swaying all over the place was too
annoying to watch.
So, yeah, some people obviously can't tell the difference between "Ouch"
and "Nice."
m
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| User: "Mickey" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 10:17:09 AM |
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On 2007-06-23, Markus Mietling <mietlingNOSPAM@googlemail.com> wrote:
Ty Ford wrote in <8ZKdnUzsG7CMjeDbnZ2dnUVZ_h7inZ2d@comcast.com>:
On the indie market, it's also because the recording talent too frequently
can't tell the difference between "Ouch" and "Nice."
Funny you should say that ...
I now shoot and edit video for a part of my living.
Gotta' nice handheld piece shot last week
This isn't what I'd call "nice," really not. I didn't sit through the
whole piece though, because your swaying all over the place was too
annoying to watch.
So, yeah, some people obviously can't tell the difference between "Ouch"
and "Nice."
The sound was nice, though, as those things go. 8-)
--
Mickey
Fast, reliable, cheap. Pick two and we'll talk. -- unknown
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---
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| User: "Ty Ford" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
24 Jun 2007 08:22:15 AM |
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On Sat, 23 Jun 2007 10:18:52 -0400, Markus Mietling wrote
(in article <9gaq739g0kg0m0l3hbonjm36j13obfljbe@4ax.com>):
Ty Ford wrote in <8ZKdnUzsG7CMjeDbnZ2dnUVZ_h7inZ2d@comcast.com>:
On the indie market, it's also because the recording talent too frequently
can't tell the difference between "Ouch" and "Nice."
Funny you should say that ...
I now shoot and edit video for a part of my living.
Gotta' nice handheld piece shot last week
This isn't what I'd call "nice," really not. I didn't sit through the
whole piece though, because your swaying all over the place was too
annoying to watch.
So, yeah, some people obviously can't tell the difference between "Ouch"
and "Nice."
m
Horses and Courses. The client liked it. You must never have seen MTV, or
Homicide- Life On The Street.
Ah! Are you in the UK?
Ty Ford
--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=4RZJ9MptZmU
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| User: "Arny Krueger" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 05:44:53 AM |
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"Dave" <dwickford@yahoo.com> wrote in message
news:1182550732.993538.241710@d30g2000prg.googlegroups.com
I have been disappointed with the audio quality of some
CDs I have bought recently. Is there a free program I
can use to get an accepted measurement of fidelity? (like
a signal to noise ratio)
I have my suspicious that some may have been stored an
MP3s and then "unripped" in the factory. So how can I
tell for certain if my CD has been an MP3, or other lossy
format? I'd hope mp3 storage would leave different
markers than the original tape, for example.
Spectal analysis can give strong evidence. Most MP3 files show signs of a
brickwall low pass filter the audio band - sometimes as low as 15 KHz or
less.
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| User: "Keith G" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
23 Jun 2007 06:10:19 AM |
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"Dave" <dwickford@yahoo.com> wrote in message
news:1182550732.993538.241710@d30g2000prg.googlegroups.com...
I have been disappointed with the audio quality of some CDs I have
bought recently.
No surprise there, but let's not get into all of that.....
Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
So you can do what - take any disks back to the shop for a refund if a
computer tells you the 'fidelity factor' is below a certain figure
whether you actually *liked* the sound or not....???
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| User: "Earl Kiosterud" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
24 Jun 2007 01:04:17 AM |
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"Dave" <dwickford@yahoo.com> wrote in message
news:1182550732.993538.241710@d30g2000prg.googlegroups.com...
I have been disappointed with the audio quality of some CDs I have
bought recently. Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
Dave,
You can, to some extent, find out what the mp3 process does to the audio for yourself. You
could get an audio editor, like Cool Edit (now in Adobe's Audition), and do some recording
yourself. Save the piece as mp3, with different bitrates, reopen it, and you'll get an idea
of what artifacts the lossy compression introduces. Years ago, when mp3 codecs were newer,
the lower bit rates, like 64K, produced a watery sound. I know that's not terribly
descriptive, but it's the best way I can describe it. They seem to be better now. The
low-data-rate streaming internet radio stations have that watery sound. You'll also notice
high-frequency loss at the lower rates. As the bit rate goes up, all that diminishes. Just
for grins, I once took a very clean-sounding piece, and compared an mp3 of it (128K, I think
it was) to the original wav, subtracting one from the other. The result was a very watery
glub-glub sound, though relatively low in amplitude compared to the original.
Regards from Virginia Beach,
Earl Kiosterud
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| User: "Ty Ford" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
24 Jun 2007 08:32:21 AM |
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On Sun, 24 Jun 2007 02:04:17 -0400, Earl Kiosterud wrote
(in article <BPnfi.1319$s%.148@trnddc02>):
Dave,
You can, to some extent, find out what the mp3 process does to the audio for
yourself. You
could get an audio editor, like Cool Edit (now in Adobe's Audition), and do
some recording
yourself. Save the piece as mp3, with different bitrates, reopen it, and
you'll get an idea
of what artifacts the lossy compression introduces. Years ago, when mp3
codecs were newer,
the lower bit rates, like 64K, produced a watery sound. I know that's not
terribly
descriptive, but it's the best way I can describe it. They seem to be better
now. The
low-data-rate streaming internet radio stations have that watery sound.
You'll also notice
high-frequency loss at the lower rates. As the bit rate goes up, all that
diminishes. Just
for grins, I once took a very clean-sounding piece, and compared an mp3 of it
(128K, I think
it was) to the original wav, subtracting one from the other. The result was
a very watery
glub-glub sound, though relatively low in amplitude compared to the original.
Regards from Virginia Beach,
Earl Kiosterud
No, Earl, that's quite a good description. I hear it first in the cymbals and
other HF info, especially if that info has a lot of stereo content.
I was playing around with iTunes a few years back and clicked on their
"stereo enhance" button before importing CSNY's "Carry On" as an mp3. The
playback sounded like it was coming out of a washing machine.
Without the enhancement, the mp3 audio was better; mp3, but better. So it's
somewhat relative.
Regards,
Ty Ford
--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=4RZJ9MptZmU
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| User: "Scott Dorsey" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
26 Jun 2007 08:52:58 AM |
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Dave <dwickford@yahoo.com> wrote:
I have been disappointed with the audio quality of some CDs I have
bought recently. Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
No, you can only listen.
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
This will never be the case for a major label release. However, as an
increasing number of records are issued by amateurs who don't necessarily
have a clue what they are doing, you may find this on some small releases.
More likely you are heaving the massive overcompression and limiting
which is currently fashionable. Everybody wants their recordings to be
louder, not necessarily to sound good.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
If you play back a recording made with a perceptual encoder like MP3
uses, and you look at the spectrum with an FFT (using a program like
SpectraFOO or some other free FFT application), it will be very obvious
that something goofy has been going on. You'll see these big square
blocks of spectrum popping in and out.
If, on the other hand, you play back a heavily limited recording on an
FFT application, you won't see much other than that the plot is a lot
denser than it otherwise would be.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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| User: "Eiron" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurementof Fidelity |
23 Jun 2007 04:30:56 AM |
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Dave wrote:
I have been disappointed with the audio quality of some CDs I have
bought recently. Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
Which CDs? Perhaps someone else has them and can comment.
--
Eiron.
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| User: "Andrew Virnuls" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
25 Jun 2007 04:15:32 PM |
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"Eiron" <E1ron@hotmail.com> wrote in message
news:5e47itF30pm0lU1@mid.individual.net...
Dave wrote:
I have been disappointed with the audio quality of some CDs I have
bought recently. Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
Which CDs? Perhaps someone else has them and can comment.
I was wondering why no-one's named any examples, so I'll give one - "Stars
of CCTV" by Hard-Fi.
My first thought on hearing that was that it had been stored using lossy
compression at some point - it suffers from that same metallic, Daleky
quality that blights DAB.
Andrew
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| User: "tony sayer" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
25 Jun 2007 04:31:35 PM |
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In article <46803068$0$8721$ed2619ec@ptn-nntp-reader02.plus.net>, Andrew
Virnuls <andrew@usemysurname.com> writes
"Eiron" <E1ron@hotmail.com> wrote in message
news:5e47itF30pm0lU1@mid.individual.net...
Dave wrote:
I have been disappointed with the audio quality of some CDs I have
bought recently. Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory. So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
Which CDs? Perhaps someone else has them and can comment.
I was wondering why no-one's named any examples, so I'll give one - "Stars
of CCTV" by Hard-Fi.
My first thought on hearing that was that it had been stored using lossy
compression at some point - it suffers from that same metallic, Daleky
quality that blights DAB.
Noooo!, you can't say that in here!, your have Dave the DAB policeman
along quicker then the word lightning conjures up w_tom ;).
With Jim his new deputy;-))
Andrew
--
Tony Sayer
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| User: "Rich" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurementof Fidelity |
22 Jun 2007 10:36:27 PM |
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Dave wrote:
I have been disappointed with the audio quality of some CDs I have
bought recently. Is there a free program I can use to get an accepted
measurement of fidelity? (like a signal to noise ratio)
Some famous commercial recordings have a low s/n being recorded at
home. I had assumed my cassette tape (forget which song now) was
bad till years later when I bought a CD and it sounded the same.
A few issues ago Maximum PC did a comparison among lossless codecs
and at 192 kb/s there was only one track where any difference could
be heard. Now mp3 is a lossy codec, but at higher bitrates I doubt
there is much difference in the sound. For mp3's I suspect that
256 kb/s is where you'll have difficulty telling the difference.
I have my suspicious that some may have been stored an MP3s and then
"unripped" in the factory.
Long ago I made a custom CD for my wife's aunt and I ripped wav files
from her CD's and remastered the tracks she wanted. She was very pleased
with the results.
Less long ago she wanted another CD. I had forgotten where I put them
and when I found them this time I ripped mp3's at 128 kb/s and remastered
the CD, she was very disappointed with the quality this time. As I recall
I needed to free up some disk space at that time so this seemed quickest.
But obviously mp3's are not as good as the original wav files.
So how can I tell for certain if my CD has
been an MP3, or other lossy format? I'd hope mp3 storage would leave
different markers than the original tape, for example.
There may be another way, there is a public database of CD's, immdb
or something like that. I'm not sure how they identify the CD, perhaps
the volume name, but I suggest that any casually remastered CD, or
any made from mp3's from the net won't have the same volume name, or
whatever they use. That is, I suggest you rip the tracks from the
CD with some software that can identify the disk from immdb, if it
cannot identify the CD, there's a good chance it's as you suspect.
Unless you've for some obscure latin CD or something, the database
is not complete, but for any popular release this should work. I
think Nero will do this, I've not done it for years though.
Note, you don't have to rip the tracks, just see if the CD can
be identified.
Cheers,
Rich
To get a good measure I'd expect some Fourier transforms and signal
analysis to be done, so this should be relevant to sci.physics.
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| User: "tonewheel" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
25 Jun 2007 08:01:11 AM |
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On 23 Jun, 04:36, Rich <some...@someplace.not> wrote:
There may be another way, there is a public database of CD's, immdb
or something like that. I'm not sure how they identify the CD, perhaps
the volume name, but I suggest that any casually remastered CD, or
any made from mp3's from the net won't have the same volume name, or
whatever they use. That is, I suggest you rip the tracks from the
CD with some software that can identify the disk from immdb, if it
cannot identify the CD, there's a good chance it's as you suspect.
Unless you've for some obscure latin CD or something, the database
is not complete, but for any popular release this should work. I
think Nero will do this, I've not done it for years though.
Note, you don't have to rip the tracks, just see if the CD can
be identified.
About 5 years ago I digitised a lot of my old vinyl LP's and burned
them to audio CD-R's. I recorded the output of a turntable through a
RIAA (sp?) filter into a computer soundcard, saved as a huge WAV,
imported into SoundForge, did a bit of click/pop removal, put in
markers to separate the tracks, normalised, saved, then used CoolEdit
2000 batch mode to split the large wavs into individual wavs for each
track, then burned to disk.
Imagine my surprise when one of the resultant CD's came up with the
correct album title and track listing from gracenote....
TWJ
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| User: "=?iso-8859-1?q?Sch=F6=F6n_Martin?=" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
25 Jun 2007 09:51:51 AM |
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tonewheel <tonewheeljackson@gmail.com> writes:
Imagine my surprise when one of the resultant CD's came up with the
correct album title and track listing from gracenote....
A couple of years ago I CDfied a couple of my brother-in-law's
LPs. I still have those tracks on my HD as .wav files and I played
one of them in one of the media players on my computer and it
identified the artist if not the album and track. I was very,
very surprised.
--
Martin Schöön <martin.schoon@gmail.com>
"Problems worthy of attack
prove their worth by hitting back"
Piet Hein
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| User: "Markus Mietling" |
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| Title: Re: How can I tell music has been an MP3? Quantitative Measurement of Fidelity |
25 Jun 2007 10:31:27 AM |
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tonewheel wrote in
<1182776471.606729.281550@o61g2000hsh.googlegroups.com>:
About 5 years ago I digitised a lot of my old vinyl LP's and burned
them to audio CD-R's. I recorded the output of a turntable through a
RIAA (sp?) filter into a computer soundcard, saved as a huge WAV,
imported into SoundForge, did a bit of click/pop removal, put in
markers to separate the tracks, normalised, saved, then used CoolEdit
2000 batch mode to split the large wavs into individual wavs for each
track, then burned to disk.
Imagine my surprise when one of the resultant CD's came up with the
correct album title and track listing from gracenote....
I can imagine your surprise :-)
Interestingly, it was precisely the gracenote database that uncovered
the Joyce Hatto scam in spite of the tracks having been manipulated to
disguise the theft.
Pristine Audio's Andrew Rose still believes [1] that the information had
been deliberately planted. I believed that too, because I thought that
track identification works with md5sum or some similar hash.
Now that I read your story, it seems to me that the gracenote database
must implement some seriously powerful pattern matching technology.
Quite amazing, IMO.
m
[1] see http://www.pristineclassical.com/HattoHoax.html
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