Some distortion in my soundfiles

[Chris Soucy]

If it is, indeed, clipping, it is impossible to "fix".

It is possible to ameliorate (make better) but not possible to replace that which has been lost.

As I said, someone is going to home in here and give you that magic bullet to "ameliorate" it, but fix totally, no, it is simply not possible.

Figure out where it's happening and nail it, once and for all, before you shoot any more stuff that is important. Once the info's gone, it's gone.

CS

[Michael Nistler]

Originally Posted by Arvid Unsgaard

The strange thing is that it not get clipped in the camera.

Hi Arvid,

First the good news - I don't think your problem is clipping. I looked at the waveform on the first clip (church singing) and the signal looks fine. If you had a clipping problem, the wavetops would not be smooth sinusoidal tops but instead would look like flat-top mountains. You see, clipping distortion flattens audio waves - once the analog to digital conversion reaches peak, everything above the max is simply all digital ones. But your waveform doesn't have flat-tops, so you don't have a clipping problem. Here's a simple explanation of the A-D quantizing problem. Let's say I have 5 binary digits to guess anyone's age: the digits are 16-8-4-2-1. Your age is 29, in our base 10 that's 16+8+4+x+1, or in digital it's 11101. Now let's do your son who is 7 years old: he's 0+0+4+2+1, or digitally 00111. So far, so good. Now let's try your 52 year old dad - oops, the highest we can go is 16+8+4+2+1 (31 years old), or digitally 11111. And how about your grandfather? Again, 31 is tops, or 11111. You see the problem? Once our A-D converter makes all ones (flat-top square wave), anything higher is still all ones. Clipping (maxing or pegging the meter in red) is not desirable. For those in the know, we call this quantization error (running out of binary digits).

Anway, perhaps part of your problem was that your microphone was too far away from the talent. In that case, perhaps you turned up the audio gain to compensate for the problem. Unfortunately, you're picking up a lot of reflected waves bouncing off floors, walls, etc before reaching your microphone. At any rate, like the clipping problem your options are limited. But perhaps you might try filtering out some of the high frequency audio (low pass filter) which might sound a bit more pleasing.

My second concern was running a mixer output (hot line level signal, 50K ohm high impedence) directly to your PD170 (requires weak microphone level signal, 600 ohm low impedence). Perhaps you shut down the PD170 amplifier gain to try to compensate for the signal mismatch, but I'm guessing you've got an impedence mismatch problem.

Next time you may want to try something like the Matchbox DB25:
http://media.zzounds.com/media/db25m...082f6c8864.pdf

Finally, if the audio sounded better in the camera, I'd guess the problem just isn't as perceptible - the camera speaker isn't a good test. If you aren't doing so already, be sure to wear a good set of headphones while monitoring the audio.

Good luck, Michael

[Arvid Unsgaard]

Hi! Michael!

What can I say, you are awesome. I learn everytime im here.

Thanks.


Arvid

[Guy McLoughlin]

Originally Posted by Arvid Unsgaard

I use the 0db peep to adjust the volume on the camera and then listen all the time on the camera sound.

Arvid, when you use the 0 dB 1 Khz tone from your Shure FP24 mixer, are you adjusting the sound level of the camera to -12 dB ?

Digital recording devices ( including cameras ) have no "head-room" past 0 dB ( any sound louder than 0 dB on your camera may cause clipping distortion ), so normally you would record the 0 dB tone from your mixer at -12 dB on your camera so that you will have an extra 12 dB of "head-room" when you record.

Also, are you using high-quality headphones to monitor the sound you are recording with your camera?

Sony 7506 headphones are pretty much the standard for monitoring sound for video.

[Arvid Unsgaard]

Thanks for all your help.

Ok, so I have some problem with my sound, not all the time but...

Yesterday I download waves that have something called clip restoration.

But what do you think i can do to make it better.

I found this:

http://www.mindspring.com/~mrichter/formula/formula.htm

Which tool step by step can I use to get it better, or sounds better?

[Arvid Unsgaard]

Originally Posted by Guy McLoughlin

Arvid, when you use the 0 dB 1 Khz tone from your Shure FP24 mixer, are you adjusting the sound level of the camera to -12 dB ?

Digital recording devices ( including cameras ) have no "head-room" past 0 dB ( any sound louder than 0 dB on your camera may cause clipping distortion ), so normally you would record the 0 dB tone from your mixer at -12 dB on your camera so that you will have an extra 12 dB of "head-room" when you record.

Also, are you using high-quality headphones to monitor the sound you are recording with your camera?

Sony 7506 headphones are pretty much the standard for monitoring sound for video.

I use a headphone that came with the mixer - I dont know the name.