Non-clipping distortion

[jndsn402]

Hi,

I am a complete noob here, so bear with me if I don't know what I'm talking about -

I recorded a few minutes of a (private) concert on my Android phone. I was fairly close to the speakers, and it was quite loud. Naturally the audio sounds horrible. I downloaded Audacity to see if I could clean it up a little. From what I understand, distortion in this kind of situation is usually caused by clipping, but the waveforms don't seem to be truncated, though they do get very high.
Any suggestions for what kind of filters/fixes might be helpful in this situation? I've attached the frequency analysis text file, if that helps.

Thanks!

[kozikowski]

I think we'd get a lot more information from a FLAC compressed segment of the actual show. You can't go over about 1MB or so, so it needs to be brief.

Koz

[steve]

Overload distortion does not necessarily clip in the classic "flat top and bottom" way - depending on what part of the system is overloading you will get different types of distortion, but in any case it is not very likely that it is fixable.

Can't really tell much from the spectrum plot. As koz said, a short audio sample (preferably Flac format) would show a lot more.

[jndsn402]

Hi,

Thanks for taking a look - here's the clip:

[steve]

Ouch, that's badly distorted. I think it's beyond rescue.
I suspect that the microphone itself has been massively overloaded.

[bgravato]

I can only hear noise... I'm afraid there's not way of recovering anything that could sound like music from that...

It's like picking a cake that has been too many hours in the oven and turned into a black piece of coal and try to make it taste sweet with a chocolate flavour...

[kozikowski]

http://www.droidforums.net/forum/droid- ... ncert.html

See: Five Finger Death Punch about half-way down. That's what we're expecting for overload standing next to the band. Yours is far worse than that and it seems to have compression artifacts in there (gargling, bubbling) as well. Does the unit seem to record normal voices in quiet rooms?

Is it possible to change the unit for better or less quality, or maybe extended recording? You may have drilled yourself into the mud with both extended or increase compression and overload.

Koz

[jndsn402]

I may have been standing a little closer than that, but the amount of noise does seem excessive. I'm not sure how to adjust the input settings on my device - I have a Samsung Moment, which runs Android, but is not a Droid.
When you say compression artifacts - is that from changing the file format? The original video is a .3gp file, which I changed to an .avi, and then posted here as a FLAC.
Thanks for your help!

[bgravato]

I may have been standing a little closer than that, but the amount of noise does seem excessive. I'm not sure how to adjust the input settings on my device - I have a Samsung Moment, which runs Android, but is not a Droid.
When you say compression artifacts - is that from changing the file format? The original video is a .3gp file, which I changed to an .avi, and then posted here as a FLAC.
Thanks for your help!

Compression artifacts refers to the distortion introduced by the compression algorithm.
When you compress an audio signal with a lossy codec (such as mp3 for example), you damage the signal and you loose information that can't be recovered. Ideally the damaged done should be inperceptible to the human hearing, but the more you compress it the more you damage it and the more distorted it will sound. Specially on mobile phones and similar equipment, which usually don't have much storage space, the degree of compression is normally very high, which means the signal might be considerably damaged by the compression algorithm.

Also the equipment (ie the mic) is usually not top quality and not tailored for music recording. It's rather optimized for voice. Also the software and compression algorithms (codecs) used are probably optimized for voice. Which means that even if you find the perfect conditions for recording the outcome will probably still not be very pristine.

[kozikowski]

The original video is a .3gp file, which I changed to an .avi, and then posted here as a FLAC.

You went through two compressions. The video capture was highly compressed and you saved it as AVI which is (usually) Windows' compressed format, effectively doubling the damage. The trip to FLAC didn't do anything wrong. FLAC is a gentle compressor that doesn't add damage.

The sound tools were all designed for a perfect show that has a little problem here and there, not a sound track with almost no show at all.

Koz