Topic: clipping in post question

[Corbin]

I've never brickwalled with my 660.  I have however had clipping on my recordings before (only very occasionnaly with a small burst of digi-noise).  I have a question or two... 

Is clipping considered one spike or does it have to be sustained?  If there is no apparent distortion or digi-noise in the clipping, is it still destructive to the recording? 

Also,
Last night, I recorded a Grand Theft Bus show outdoors.  I ran the -20db pad on the 660 (when I shouldn't have).  So when I got home and loaded the wav into SoundStudio, the volume of the show had to be increased.  I amlified the show and made it sound louder.  When I did this however, I induced (or created) spikes in the recording that clipped at some points.  There was no digi-noise that I could notice so I left it like it was. 

Is this kind of clipping (caused by me in post during amplifying) destructive or negative for the recording?  I would lean towards believing that this kind of clipping would be less problematic than one that is present on the master.

I hope I explained that properly...

Adam

[boojum]

Corbin, if you have the original try normalizing it.  Normalizing can be set to prevent clipping.   ;o)

[Brennan]

Adam, that makes perfect sense actually

It really depends on how loud you go in post. Certainly, if you crank it a bit too loud you're gonna hear the clipping, but in most cases it isn't a problem. Someone on here once pointed out spikes in the waveform on a factory CD resembling clipping, but it wasn't audible.

Hope that makes sense

[Brian Skalinder]

Is clipping considered one spike or does it have to be sustained?    If there is no apparent distortion or digi-noise in the clipping, is it still destructive to the recording?

I believe clipping is defined as three or more consecutive samples at 0 dBFS.  Whether your ears hear it or not depends on a lot of factors, IME:  source material, ADC used, playback gear / environment, ears, etc.  If the master's clipped, some post-processing can get really ugly, so try not to clip on the master, ever.  If you do, you're potentially hosing your post-processing options.

I amlified the show and made it sound louder.  When I did this however, I induced (or created) spikes in the recording that clipped at some points.  There was no digi-noise that I could notice so I left it like it was.

No need to amplify to the point of clipping.  Most s/w editors provide a way to amplify without clipping.  If it were me, I'd go back and re-do it.

Is this kind of clipping (caused by me in post during amplifying) destructive or negative for the recording?

It's definitely destructive and negative for the recording.  The question is whether you can hear it, and if you can't, whether you care.  There's simply no reason to clip in post.  One way to think about it:  <a> you post-process a recording, <b> you share it with others, <c> your master is lost or destroyed, <d> now the best source available is clipped.  Would you be happy if the only available source of one of your recordings that included clipping due to your own post-processing?  I wouldn't.

All else equal, I guess ultimately it comes down to not a question of "why wouldn't you clip in post-processing", but more a question of "why would you clip in post-processing"?

[Corbin]

Thanks for the responses, especially the one from Brian...Thanks Brian for going into so much detail.  And I undertand what you're saying..

Just when I think that I have all this shit figured out (for the most part), I realize that I don't really know what I'm doing (especially in post I guess).  I don't think taping is the ideal hobby for a borderline OCD perfectionist..I'm constantly wanting to go back and remaster all my recordings (and then I'll want to do it again in a few months once I'm even  more knowledgeable with Sound Studio.)

Sure beats quilting or playing bridge though.

[ghellquist]

In post I tend to do the following.

1 - remove the very lowest frequencys with a high-pass filter. Depending on the music, 20 or 30 Hz. Generally no music down there anyway, just muck.
2 - increase levels to a comfortable level. I do this in my computer program that runs internally at 32 bit float, so overs are never a problem inside the program. Of course overs, clipping that is, will be a problem if they are exported from the program, that is why step 3 is there.
3 - last in the chain in my program I put a limiter set to -2dB. This avoids any clipping in playback. Doing the limiting inside the program I get control of whether it will be heard or not.

The program I use is Samplitude, but similar things are available in many other programs. As a low cost solution I can recommend Magix Audio Studio deLuxe if you are on PC platform. It costs a bit more that Audacity (which is free) but the difference is worth it (to me at least). To each however, his own favourites.

Now for the other things I might do, depending on situation.
- different volume setting on songs vis applauds from the crowd. Sometimes, the applauds can be louder than the music, well, on the finished product it is better the other way round.
- cutting up in nice pieces as CD tracks, ie removing dead periods between songs.
- very gently EQ to compensate for room modes -- this takes very good listening equipment, otherwise I might compensate for the errors at home, not what you want to do.

A bit of work to get to know how to use the program (and to get the right program) but there really is an advantage to a bit of after-the-recording polishing.

Gunnar

[Corbin]

Thanks Gunnar!

[Corbin]

Here's the show I'm talking about in case you're curious...
http://www.archive.org/details/gtb2007-07-18.lsd2.acm660.flac16