"Dave" wrote in message
oups.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.

"Dave" wrote in message
oups.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....???

On Jun 22, 2007, Dave commented:

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.
------------------------------snip------------------------------

If they're major-label CDs, I'd be floored if they were making CDs from
data-compressed files like MP3s. There's just no reason to do it.

There have been cases where pirated recordings or shared files have been
"up-rezzed" from lossy files, and radio stations have sometimes used lossy
files on air (particularly commercials). I found this on the net:

For some odd reason, there are people who foolishly convert MP3 files to FLAC
(or APE), perhaps in the mistaken belief that it will make the signal "sound"
better. This is the sonic equivalent of taking a 1" square photograph and
blowing it up to 10", believing it will look as good as an original 10"
photograph.

"A shareware Windows program called "AudioChecker" can analyze various kinds
of FLAC, APE, and other lossless files and then intelligently make a guess as
to whether the files are legit or just "uprezed" from an MP3 file, based on
technical factors like frequency response. AudioChecker is available from:

http://www.dester.hu


I haven't used the program, so I can't say for a fact that it works, but MP3
artifacts are very noticeable if you know what to listen for. I don't doubt
you're hearing something bad, but it's possible you may be hearing some other
kinds of distortion in the track.

--MFW

Marc Wielage wrote:

For some odd reason, there are people who foolishly convert MP3 files to FLAC
(or APE), perhaps in the mistaken belief that it will make the signal "sound"
better.

Sounds like those who buy "tubed" CD players, thinking that the one
tube stage at the player's output will somehow "fix" all the "harm"
done to the signal by all the solid-state stuff.

"dizzy" wrote in crossposted message
...
Marc Wielage wrote:

For some odd reason, there are people who foolishly convert MP3 files
to FLAC
(or APE), perhaps in the mistaken belief that it will make the signal
"sound"
better.

Sounds like those who buy "tubed" CD players, thinking that the one
tube stage at the player's output will somehow "fix" all the "harm"
done to the signal by all the solid-state stuff.



Why? Doesn't it?

"Keith G" wrote in message
...

"dizzy" wrote in crossposted message
...
Marc Wielage wrote:

For some odd reason, there are people who foolishly convert MP3 files to
FLAC
(or APE), perhaps in the mistaken belief that it will make the signal
"sound"
better.

Sounds like those who buy "tubed" CD players, thinking that the one
tube stage at the player's output will somehow "fix" all the "harm"
done to the signal by all the solid-state stuff.



Why? Doesn't it?


Not to mention all those nasty digits which disappear into the vacuum of the
tubes......

S.

--
http://audiopages.googlepages.com

"Serge Auckland" wrote in message
...


"Keith G" wrote in message
...

"dizzy" wrote in crossposted message
...
Marc Wielage wrote:

For some odd reason, there are people who foolishly convert MP3
files to FLAC
(or APE), perhaps in the mistaken belief that it will make the
signal "sound"
better.

Sounds like those who buy "tubed" CD players, thinking that the one
tube stage at the player's output will somehow "fix" all the "harm"
done to the signal by all the solid-state stuff.



Why? Doesn't it?


Not to mention all those nasty digits which disappear into the vacuum
of the tubes......


I wonder how many CDs you can play before the valves fill up with lost
digits?

But, on a more serious note, I have often wondered if 'tubed' CDPs sound
any better (I've never heard one myself) - having witnessed a vast
number* of people here being staggered backwards to hear CDs (including
their own) played through valve amps for the first time!!


*OK, maybe half a dozen or so...??

"Dave" wrote in message
oups.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

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

In article .com,
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.

CBS television news played part of a Beatles song because they were
talking about Paul's divorce. It was in tune. It is slightly out of tune
on the two or three CD versions I have of it. It went through the
optical cable to a Harman Kardon AVR 240 from a cable TV box 48 Khz PCM.

John Lennon answered a question "Why is The Beatles music so popular?",
He said, "We don't know. We really don't know. If we knew we would be
managers."

The Beatles liked the movie "The Girl Can't Help It." starring Jane
Mansfield, about a couple of gangsters who controlled the jukebox
business.

I can't demonstrate how the 30 to 40 year old music was perfectly in
tune years ago to my nephews and nieces. They like the music, but they
will probable never know what all the excitement was about.

Maybe you just have to know who to bribe and how much to pay if you want
to communicate a voice or guitar note that is perfectly in tune to the
public. Maybe MP3, aiff, SACD etc. doesn't make that much difference.

Cliff Nelson

Dry your tears, there's more fun for your ears,
"Forward Into The Past" 2 PM to 5 PM, Sundays,
California time,
http://www.geocities.com/forwardintothepast/
Don't be a square or a blockhead; see:
http://bfi.org/node/574

http://library.wolfram.com/infocente...s=1;search_per
son_id=607