Hydrogenaudio Forums > How to find out if a CD was burned from mp3?

Kenneth Hansen

Jul 11 2006, 05:07

Is there any way to find out if a "burned" music CD was made from MP3´s or from a CD-to-CD copy?
Is this information still there or was it lost?

The reason I ask, is that I´ve just bought myself an Ipod. And wish to convert my CD´s to AAC for use on my Ipod.
But I don´t want to rip from the CD´s that was originally made by myself from MP3 files. The Quality would suffer too much, I feel.
I´ve forgotten which ones was made from MP3´s and which was copied one-to-one from CD. So.... Is there a way of finding out?

Thanks in advance

jmartis

Jul 11 2006, 05:13

Tau Analyzer

(edit- added link)

Kenneth Hansen

Jul 11 2006, 05:27

QUOTE(jmartis @ Jul 11 2006, 13:13)

Tau Analyzer

(edit- added link)

Thanks!

I´m trying it our right now!

dobyblue

Jul 13 2006, 14:16

In all honesty as well though once you've ripped to mp3 there's not going to be much loss in quality from going back to .wav and then back to .mp3 again.
IPODs now have firmware that supports lossless and gapless .flac, .shn and .ape compression. This way you're compressing to 50% (approx) the size of your CD and not losing any of the key audio information.

jmartis

Jul 13 2006, 14:24

QUOTE(dobyblue @ Jul 13 2006, 22:16)

In all honesty as well though once you've ripped to mp3 there's not going to be much loss in quality from going back to .wav and then back to .mp3 again.

but there IS a quality loss, more or less noticeable

QUOTE(dobyblue @ Jul 13 2006, 22:16)

IPODs now have firmware that supports lossless and gapless .flac, .shn and .ape compression. This way you're compressing to 50% (approx) the size of your CD and not losing any of the key audio information.

any of the KEY information? you do not lose ANY audio quality, since it is lossless

J.M.

ddrawley

Jul 13 2006, 14:27

MP3 is a lossy format by design, so you will lose quality transcoding. How much quality depends on several factors (bitrate, encoder, decoder, etc)
Only your own ABX tests can help you decide if you can live with the quality degradation.
All that said, most on this forum recommend against transcoding.
This does not apply to lossless codecs of course (FLAC, WAVPACK)

dobyblue

Jul 13 2006, 15:35

QUOTE(jmartis @ Jul 13 2006, 16:24)

QUOTE(dobyblue @ Jul 13 2006, 22:16)

In all honesty as well though once you've ripped to mp3 there's not going to be much loss in quality from going back to .wav and then back to .mp3 again.

but there IS a quality loss, more or less noticeable

QUOTE(dobyblue @ Jul 13 2006, 22:16)

IPODs now have firmware that supports lossless and gapless .flac, .shn and .ape compression. This way you're compressing to 50% (approx) the size of your CD and not losing any of the key audio information.

any of the KEY information? you do not lose ANY audio quality, since it is lossless

J.M.

Yes but there is other information, irrelevant to the audio, that can be lost.
The key information is the audio.

The noticeable quality loss is from the first generation conversion to mp3. Once you convert that lossy file back to .wav and to .mp3 again there will not be a noticeable quality loss unless you spend all day converting back and forth.

http://db.etree.org/dobyblue

gameplaya15143

Jul 14 2006, 08:55

QUOTE(Kenneth Hansen @ Jul 11 2006, 07:07)

Is there any way to find out if a "burned" music CD was made from MP3´s or from a CD-to-CD copy?

What I would do is start up my trusty AnalFreq 1.8 (spectrum analyzer, freeware) and pay close attention to any differences that appear at 16khz. Depending on the bitrate used (and especially if it was a low bitrate mp3) there will be a sharp drop in the presence of frequencies above 16khz. This is a 100% tell-tale sign that the track was at some time an mp3 (this only happens with mp3).

You can also look and see if a lowpass filter was used (another sign of lossy compression).

Digga

Jul 14 2006, 09:06

QUOTE(dobyblue @ Jul 13 2006, 23:35)

Yes but there is other information, irrelevant to the audio, that can be lost.
The key information is the audio.

what other information besides the audio is present? please elaborate, because my guess is that you don't know what you're talking about

QUOTE

The noticeable quality loss is from the first generation conversion to mp3. Once you convert that lossy file back to .wav and to .mp3 again there will not be a noticeable quality loss unless you spend all day converting back and forth.

that's a bold statement that is just an assumption. see the big TOS link.

QUOTE

IPODs now have firmware that supports lossless and gapless .flac, .shn and .ape compression. This way you're compressing to 50% (approx) the size of your CD and not losing any of the key audio information.

it's more like 60% overall.

dobyblue

Jul 14 2006, 10:53

QUOTE(Digga @ Jul 14 2006, 11:06)

what other information besides the audio is present? please elaborate, because my guess is that you don't know what you're talking about

No problem.

QUOTE

Why doesn't FLAC store all WAVE metadata?

FLAC is a general-purpose audio format, not just a compressed WAVE file format. There's a subtle difference. WAVE is a complicated standard; many kinds of data besides audio data can be put in it. FLAC's purpose is not to reproduce a WAVE file, including all the non-audio data that is in it, it is to losslessly compress the audio.

People have asked for that in FLAC, but if it were added, then what about similar formats like AIFF? flac can extract and compress audio data in an AIFF file also. AIFF is widely used on the Mac. AIFF users have asked that all AIFF metadata be stored for the same reasons. And it doesn't end there, other uncompressed formats exist.

Also, it would add a lot of complexity to FLAC because non-audio data has to go in the metadata section which is at the beginning of the FLAC file. But in WAVE and AIFF it can go before or after the audio, so the encoding would have to make multiple passes and also store the chunk hierarchy to be able to reproduce it.

There's also other data such as the tag info that allows certain players to see the file information such as the artist and track name that is not stored in the FLAC file. For example Oasis' "Be Here Now" CD contains additional information that allows most of the modern car front heads to display the names of the tracks as they play. If you convert to .flac and then back to .wav you will lose this information, but you will maintain the KEY data of the file; the audio data.

I have over 200 live concerts from various different artists and in my experience with FLAC the majority of files compress to around 50% of the original file size.

QUOTE(Digga @ Jul 14 2006, 11:06)

it's more like 60% overall.

Actually at the default setting of 5 you'll get compression of about 52-53% - if you have the time and choose maximum compression you'll get down to an average of 50% compression. There are of course going to be some files in an album that hit 60-70% compression and others that compress down to as low as 30%, but overall you should be able to take most albums and reduce them to around 50% at maximum setting.
Cheers,
~burkey

greynol

Jul 14 2006, 11:49

QUOTE

This is a 100% tell-tale sign that the track was at some time an mp3 (this only happens with mp3).

It most certainly IS NOT a tell-tale sign! Did you ever stop to think that the source file may actually lack frequencies above 16kHz?

Cosmo

Jul 14 2006, 12:10

QUOTE(dobyblue @ Jul 13 2006, 17:35)

QUOTE(jmartis @ Jul 13 2006, 16:24)

QUOTE(dobyblue @ Jul 13 2006, 22:16)

IPODs now have firmware that supports lossless and gapless .flac, .shn and .ape compression. This way you're compressing to 50% (approx) the size of your CD and not losing any of the key audio information.

any of the KEY information? you do not lose ANY audio quality, since it is lossless

J.M.

Yes but there is other information, irrelevant to the audio, that can be lost.
The key information is the audio.

QUOTE(dobyblue @ Jul 14 2006, 12:53)

QUOTE(Digga @ Jul 14 2006, 11:06)

what other information besides the audio is present? please elaborate, because my guess is that you don't know what you're talking about

No problem.

QUOTE

Why doesn't FLAC store all WAVE metadata?

FLAC is a general-purpose audio format, not just a compressed WAVE file format. There's a subtle difference. WAVE is a complicated standard; many kinds of data besides audio data can be put in it. FLAC's purpose is not to reproduce a WAVE file, including all the non-audio data that is in it, it is to losslessly compress the audio.

People have asked for that in FLAC, but if it were added, then what about similar formats like AIFF? flac can extract and compress audio data in an AIFF file also. AIFF is widely used on the Mac. AIFF users have asked that all AIFF metadata be stored for the same reasons. And it doesn't end there, other uncompressed formats exist.

Also, it would add a lot of complexity to FLAC because non-audio data has to go in the metadata section which is at the beginning of the FLAC file. But in WAVE and AIFF it can go before or after the audio, so the encoding would have to make multiple passes and also store the chunk hierarchy to be able to reproduce it.

There's also other data such as the tag info that allows certain players to see the file information such as the artist and track name that is not stored in the FLAC file. For example Oasis' "Be Here Now" CD contains additional information that allows most of the modern car front heads to display the names of the tracks as they play. If you convert to .flac and then back to .wav you will lose this information, but you will maintain the KEY data of the file; the audio data.

WAV is a container format. CD digital audio is not WAV. CDDA (per the Red Book audio specification) is raw PCM, which has no inclusion of metadata (tags).

If present, track info on a CD is stored as CD-Text in the TOC (table of contents, in the lead-in area of the disc). CD-Text isn't part of the data that is ripped from CD to WAV (or whatever format you may rip to). The info stored as CD-Text can be extracted from the TOC and added into the WAV (RIFF) header, if your software is capable, but that is really no different than getting the info from a freedb / CDDB database ... it's added after the fact, and is not part of the ripped data.