Prev: Recommend turntable $150 - $200
Next: Free Mp3's and Lyrics Search Engine!
From: Dennis Q. Wilson on 6 May 2008 14:24
Is there any software to tell whether an audio track was actually
converted from an MP3 or WMA file, rather than ripped from a CD?
From: Scott Dorsey on 6 May 2008 14:48
In article <c46b389d-d52e-418b-969c-3548a509b226(a)z24g2000prf.googlegroups.com>,
Dennis Q. Wilson <DennisQWilson(a)yahoo.com> wrote:
>Is there any software to tell whether an audio track was actually
>converted from an MP3 or WMA file, rather than ripped from a CD?

If your ears won't tell you, looking at a spectrogram probably will. If you
see big blocky squares... that's a sign of compression.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
From: Paul Stamler on 6 May 2008 15:16
"Dennis Q. Wilson" <DennisQWilson(a)yahoo.com> wrote in message
news:c46b389d-d52e-418b-969c-3548a509b226(a)z24g2000prf.googlegroups.com...
> Is there any software to tell whether an audio track was actually
> converted from an MP3 or WMA file, rather than ripped from a CD?

Probably the easiest way is to use a program which has a spectrum analyzer.
(Adobe Audition is one, there are many others.) If there's a sharp cutoff at
around 15kHz then the file came from a lowish-bit-rate .mp3 or .wma file. If
the original was high-bitrate, though, it's harder to tell.

Peace,
Paul


From: Arny Krueger on 6 May 2008 15:16
"Dennis Q. Wilson" <DennisQWilson(a)yahoo.com> wrote in
message
news:c46b389d-d52e-418b-969c-3548a509b226(a)z24g2000prf.googlegroups.com

> Is there any software to tell whether an audio track was
> actually converted from an MP3 or WMA file, rather than
> ripped from a CD?

AFAIK, detecting a MP3 is a study in audio forensics. You collect evidence
and infer a conclusion from it.

Two kinds of evidence that are fairly reliable:

(1) Spectrogram shows a brick-wall roll-off, often at 16 KHz

(2) MP3 frames are usually 417 or 418 bytes, so a wav file that is based on
an MP3 should be an integer number of frames long.

If the bitrate was low enough, the poor fidelity is more evidence.


From: Don Pearce on 6 May 2008 16:23
On Tue, 6 May 2008 11:24:32 -0700 (PDT), "Dennis Q. Wilson"
<DennisQWilson(a)yahoo.com> wrote:

>Is there any software to tell whether an audio track was actually
>converted from an MP3 or WMA file, rather than ripped from a CD?

Have a look at this:

http://81.174.169.10/odds/identmp3.gif

It is the spectrogram of a few seconds of music on a CD, followed by
the same piece following 256k conversion to MP3. The differences are
obvious, the main one being the complete lack of low level detail
above 16kHz - only the peaks are showing. Apart from that, the whole
appearance of the MP3 section is more granular which is evidence of
the amount of data you can discard because it is masked. Audibly, the
two pieces are essentially identical.

The piece I have used is opera with virtually no amplitude compression
- that being the kind of stuff that MP3 does best; it really doesn't
like having to cope with hypercompressed pop music that doesn't
contain the kind of low level detail that can be masked away.

Anyway, what this shows is that visually it is very easy to tell a
file that has been through MP3 conversion from one that hasn't.

d

--
Pearce Consulting
http://www.pearce.uk.com
 |  Next  |  Last
Pages: 1 2 3
Prev: Recommend turntable $150 - $200
Next: Free Mp3's and Lyrics Search Engine!