Noise artefact in mp3-compression

Hi
When ripping music to mp3-files using Lame 3.92, I sometimes get a high
pitched noise, which is not on the original .wav-file. It is reproducable. I
think it is some kind of interference between high and low frequency
content. The pitch doesn't shift throughout the track. I have tried to
resample to 48 kHz/24 bit. This shifts the noise upwards and attenuates it
to some extend, but it doesn't "cure" the problem.

Any ideas of, what is going on and I can do to get rid of it. Some kind of
filtering?

Hans

Do you have the same problem with other, newer versions of LAME?  Go to
Rarewares.org to get the latest versions, including a handy 'lame drop'
program which makes it easy to change settings and do new test encodings
etc.  Just drag & drop the source and it spits out a mp3.

If not, then that solves the problem.

If so, then there is probably something wrong with your source.

Have you tried looking at both the source and the mp3 using a wav editor,
just to see what freq's are present?

Is the source at 44khz?  If not, perhaps your lame settings are resampling
it automatically and causing problems.

Do you have the problem when you use a different player?  It's quite
possible that you have a buggy mp3 player.  They do exist.

Try looking through HydrogenAudio.org forums, and if you can't find
anything, post a question.  The author of LAME frequents there, as do a lot
of experienced LAME users.

"Sol Sert" <sertindole@hRoEtMmOaViEl.com> wrote in message
news:4193a61b$0$240$edfadb0f@dread12.news.tele.dk...
> Hi
> When ripping music to mp3-files using Lame 3.92, I sometimes get a high
> pitched noise, which is not on the original .wav-file. It is reproducable.
> I think it is some kind of interference between high and low frequency
> content. The pitch doesn't shift throughout the track. I have tried to
> resample to 48 kHz/24 bit. This shifts the noise upwards and attenuates it
> to some extend, but it doesn't "cure" the problem.
>
> Any ideas of, what is going on and I can do to get rid of it. Some kind of
> filtering?
>
> Hans
>




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On Thu, 11 Nov 2004 18:49:18 +0100, "Sol Sert"
<sertindole@hRoEtMmOaViEl.com> wrote:

>When ripping music to mp3-files using Lame 3.92, I sometimes get a high
>pitched noise, which is not on the original .wav-file. It is reproducable. 
I
>think it is some kind of interference between high and low frequency
>content. The pitch doesn't shift throughout the track. I have tried to
>resample to 48 kHz/24 bit. This shifts the noise upwards and attenuates it
>to some extend, but it doesn't "cure" the problem.
>
>Any ideas of, what is going on and I can do to get rid of it. Some kind of
>filtering?

What bitrate are you using? It's in the nature of MP3 compression that it
distorts the signal, and the lower the bitrate, the greater the distortion
will be.

It's also possible that you have a "bad" build of the encoder (did you
compile it yourself, or did you download a pre-built encoder from
somewhere?), or that it's the decoder, not the encoder, that's creating the
noise. So, you might try a more recent version of LAME and/or a different
decoder. LAME 3.92 is perhaps two years old now: no doubt there have been
quality improvements since then.

Or, maybe you simply have sensitive ears. Some people are very good at
noticing the characteristic distortion in MP3s and other lossy formats.

-- Mat.

Hi, I think I'm using ver. 3.96 now, and it has the same problem. I found
some references to the problem on the net. It is present especially at lower
bit-rates (128 or less), which does not seems to be the problem with the
Fraunhofer codec.
So thanks for the input!

"Mathew Hendry" <TJLWBECGSGWU@spammotel.com> skrev i en meddelelse
 news:mdtbp0tg8ul8ieefbifb5s5udta7209c7m@
4ax.com...
> On Thu, 11 Nov 2004 18:49:18 +0100, "Sol Sert"
> <sertindole@hRoEtMmOaViEl.com> wrote:
> 
>
> What bitrate are you using? It's in the nature of MP3 compression that it
> distorts the signal, and the lower the bitrate, the greater the distortion
> will be.
>
> It's also possible that you have a "bad" build of the encoder (did you
> compile it yourself, or did you download a pre-built encoder from
> somewhere?), or that it's the decoder, not the encoder, that's creating
> the
> noise. So, you might try a more recent version of LAME and/or a different
> decoder. LAME 3.92 is perhaps two years old now: no doubt there have been
> quality improvements since then.
>
> Or, maybe you simply have sensitive ears. Some people are very good at
> noticing the characteristic distortion in MP3s and other lossy formats.
>
> -- Mat.
>

Sol Sert wrote:
> "Mathew Hendry" skrev 

[snip]

> Hi, I think I'm using ver. 3.96 now, and it has the same problem. I found
> some references to the problem on the net. It is present especially at low
er
> bit-rates (128 or less), which does not seems to be the problem with the
> Fraunhofer codec.
>
Sounds interesting. Could you please put a (small) fragment of such an
mp3 (and a losslessly compressed version of the original) online
somewhere? If you cannot, I would be happy to put it online somewhere for
you - just send it by e-mail to me then.


Regards,

Wimjan

--
Sleet is van vroeger, tegenwoordig gaat alles kapot.