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Topic: Removing Static From MP3's (Read 8584 times) previous topic - next topic

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  • JyushinX
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Removing Static From MP3's
Hi,

I have a group of MP3's in my collection that I believe were created from an original analog source (record or tape) and because of this there is a noticeable hiss/static in the background of all the songs.

Is there any way to effectively remove or minimize this static? The music itself is not available on CD and is very rare, so this is my only option.

Thanks.

  • magic75
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Removing Static From MP3's
Reply #1
You could try using some software that can do noise image suppression (there may be other names for it). Basically it works like this: You need a part of the recording where only the noise/static is present. Usually there are parts in the beginning and/or the end of the song. Then you scan this section with the software, which builds a mathematical model of the noise. Using this model you can then let the software suppress the noise (over the whole file of course).

Cool Edit / Adobe Audition have good tools for this. If you are looking for a free alternative to begin with EAC has this feature as well. I think Audacity has it as well.

  • Antonski
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Removing Static From MP3's
Reply #2
... but don't expect miracles  ...

  • .zolder
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Removing Static From MP3's
Reply #3
can't you regenerate the static noise (probably 50hz), make sure it has the same volume as the original static noise, then invert the newly made noise and mix the 2?

a long shot

  • ManK
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Removing Static From MP3's
Reply #4
Directx plugins such as waves x-noise, soundforge noise reduction can remove this type of noise quite effectively (from my limited experience). However they are quite expensive. Adobe audition also has a very good noise reduction function and I believe it comes with 30 day free trial.

  • magic75
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Removing Static From MP3's
Reply #5
Quote
can't you regenerate the static noise (probably 50hz), make sure it has the same volume as the original static noise, then invert the newly made noise and mix the 2?

a long shot

I am not sure that will work. Noise is random so the probability of samples cancelling eachother out should be as large as the probability of them adding up. If i remember my signal processing correctly this should not reduce nor increase the noise.

Using a noise image approach would give much more accurate results anyway. At least Cool Edit seems to be smart enough to switch off the noise reduction when the music is much louder than the noise.

  • .zolder
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Removing Static From MP3's
Reply #6
i thought static noise wasnt random? that's why i mentioned the 50hz.

basically, you mean within the 50hz pattern, the individual waves are random?
  • Last Edit: 28 April, 2004, 07:59:00 AM by .zolder

  • magic75
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Removing Static From MP3's
Reply #7
Ah, sorry. You are right, that kind of noise could be cancelled out that way.  But you would still have to find the correct phase offset and amplitude for the noise signal to be cancelled out. Seems like some work is needed to do that, and you will only be removing the statci 50 Hz noise signal, nothing else. Noise image suppression should be able to reduce all the noise, and with less work needed.

  • Andavari
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Removing Static From MP3's
Reply #8
I'd say no matter what the tracks sound like, try to work with original wav files, even if you have to start from scratch -- hence if you play around with the mp3's and then end up transcoding you'll have even less quality.

One thing I did when capturing all my cassettes was to use a tape deck that had Dolby B Noise Reduction, it surely beats manually applying noise reduction which may have mixed results.
Complexity of incoherent design.

  • magic75
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Removing Static From MP3's
Reply #9
I think he said that he only had the MP3:s. Anyway, perceived quality degradation due to transcoding should be significantly less than the quality degradation due to the static/noise. But the best thing would of course to decode to wav, process the files, and then not encode lossy again, ie use some lossless format.
  • Last Edit: 29 April, 2004, 09:18:18 AM by magic75

  • 2Bdecided
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  • Developer
Removing Static From MP3's
Reply #10
Beyond that, declickers typically don't work as well with (decoded) mp3s as they do with (original) wavs. Denoisers are OK though.

Cheers,
David.

  • magic75
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Removing Static From MP3's
Reply #11
Quote
One thing I did when capturing all my cassettes was to use a tape deck that had Dolby B Noise Reduction, it surely beats manually applying noise reduction which may have mixed results.

If the tape was recorded with Dolby NR then of course the best thing is to play it back with Dolby NR on. But if it wasn't I can't see that being a good idea, since Dolby amplifies high frequencies on recording and attenuates them on playback. On tapes not recorded with Dolby that would mean losing HF material if playbacked with Dolby on...

The opposite applies as well, i.e playing tapes recorded with Dolby with Dolby NR turned off. That would mean getting an unwanted HF boost.