Audacity Forum

I used a Sansa mp3 player to record something recently, but it was too near the speakers so it recorded too loudly. Every time the person's voice goes up, there is a loud scratch noise because it's too loud. Is there any way to remove all this? The noise removal doesn't work as this isn't background static or whatever. I recorded too loud and I wanna get rid of that, is it possible?

Thanks for the help.

Note: I tried click removal.

You may be out of luck on this one, but there is a very slim chance of recovery.
Can you upload a short (just a few seconds) of a badly affected part (as a WAV file) somewhere on the internet and post a link to it so that we can have a look at it.

Actually the person who's voice was recorded would not like me to make it public, sorry.

Most of it is okay, but like I said, during the parts when the mic got loud you hear a very annoying crack sound for a second or less. Once in a while it'll last 2 seconds or so...

Maybe you can mention the repair method you were talking about and I'll give it a try anyway and see what happens.
Thanks for the help.

I was thinking of using "Clipfix", but possibly in a slightly non-standard way.

Clipfix is available in some of the most recent versions of Audacity 1.3 (beta), and is available as a plug-in for all other 1.3 versions.

Clipfix works by "rounding off" peaks that have been "hard clipped" (flat at the top due to digital clipping).

Basically, the noise that you can hear on the over-loud parts are caused by "clipping", but there are a number of variations on exactly how your recorder has clipped.

In the best case, the recorder has simply truncated sample values that go beyond 0 dB. In this case Clip fix will work very well as the clipped waves will have perfectly flat tops. You will need to reduce the amplitude of the entire recording (Use "Normalize" to about -6 dB or less) to allow "headroom" for the wave tops to be reconstructed, then apply Clipfix. In this scenario, the default settings on Clipfix should work very well.

In a not quite so good scenario, the clipping will start with "soft" clipping - a kind of "hard limiting" which will "squash" down the peaks before the onset of hard clipping. This would require that you deliberately increase the clipping so that you have hard clipping that Clipfix can deal with.

In the worse case scenario, some recorders will reverse the polarity of samples above 0dB (see this post for an example http://audacityteam.org/forum/viewtopic ... =20#p16990 ). In this case there is so far no way of fixing it with Audacity, or as far as I know, any other software.

Note that Clipfix is rather slow, and uses a lot of RAM, so if you have a long recording to process, you may want to cut it up into smaller chunks.

Yes. Digital overload is one of the killers. Even if ClipFix works, it may not sound quite right in the final show. It's extremely difficult to solve digital peak distortion.

Koz

kozikowski wrote:Even if ClipFix works, it may not sound quite right in the final show.

When Clipfix repairs the damage, it is essentially just extrapolating the curves at either side of the damage (with a bilinear function) so it is by no means accurate to what should have been there, but in practice it can work extremely effectively and be a real life saver. As said before - if you have the reverse polarity problem, you're stuffed.

Thank you for your help.

I have tried clipfix...but I guess this audio is too damaged. It doesn't remove the annoying chkchkchk sound, it lowers it a bit but also lowers the quality of the audio.

Next time I guess I'll stand further away from the mic lol.

But I noticed about this Sansa mp3 player (it has a record function), it almost always clips. Depending how loud the mic is and how far I am from the speakers, it'll clip less or more. But how do I muffle it while recording? I tried wrapping it in 3 (clean) socks and putting it in my pocket, but that day I was very close to the speakers to it just went overboard with the clipping despite what I did.

<<<I guess this audio is too damaged.>>>

Almost without exception, by the time normal humans realize they need the repair packages, it's too late. I know of one time exactly where a producer got rid of a really low air conditioning noise in an interview and the show was a great success. Once. Ever.

OK. Lets prevent this problem in the first place.

<<<Sansa mp3 player>>>

There's only about a hundred of those. Which one have you got? Model numbers are good.

Koz

I apologize for not being clearer.

Sandisk Sansa e280 (8gb) Mp3 player
http://reviews.cnet.com/mp3-players/san ... 41576.html

I've searched on Google, but Sandisk don't like to give out much technical information.

It looks like the SanDisk Sansa e280 records as MP3 or WMA - lossy formats. This can make a repair job a bit more difficult as the damage (digital clipping) will have been distorted to some extent by the data compression.

moonie wrote:Actually the person who's voice was recorded would not like me to make it public, sorry.

Would they allow you to post a 1 or 2 second clip of an affected part? We may be able to suggest some settings that will give you an optimal repair. Without an audio sample it is difficult (impossible?) to offer any further help.

To post a 2 second clip, you can use Audacity to make the clip (select 2 seconds of the audio track, then choose "Export Selection" from the File menu, and export it as a WAV file. If you then "Zip" the exported audio you will be able to add it as an attachment to your forum post.