Sound Forge & clipping question...

[JonUrban]

Steve,

If I take a CD and extract a track to a wav editor like SOUND FORGE, and that track displays "clipping", meaning that the peaks come all the way to the top of the window (I know you know what clipping is, I just want to be sure I am describing it correctly!), is that an indication of bad mastering, or bad creation of the CD?

Should this not be the case????

:-jon

[Paul L.]

I'm not Steve, as you can tell, but . . .

A waveform can come up to the top without clipping.

Te tell visually if it's clipping, you have to examine whether the natural curve of the waveform has been flattened at the peaks. Zoom in and check it out. If just the highest point of the curve has reached 100% but there hasn't been any flattening on top, it should be okay.

I have seen commercial CDs that have clipping on them, but not often.

Very frequently the problem with modern CDs and modern remasterings is that they have had their sound compressed like crazy, and the portions of the music that should be quiet have been made loud. Everything is loud. There's hardly any dynamic range, sometimes 2dB or so instead of 40dB, say. Lots and lots of portions are at or near 100%. It's bad bad bad.

[Grant]

Paul L. is right. The CD is probably not clipped.

[ascot]

Ditto for me. I've checked out the possible number of clips in Cool Edit and it came back with a percentage of .001% or something. Yet the wave form is maxed out all over the place.

[JonUrban]

Thanks for the fast answers, guys. I was making a compilation CD for my car, and I used SF to extract the wav files.

Some of them were "well behaved", sitting nicely within the screen space of the editor. Others looked like brick walls, with peaks appearing to hit the top. The "meters" of Sound Forge (6.0) were thumping into the red, but the "clip" indicator never appeared.

But it sure looked like it was damn close.

These must be the "compressed" or "Smile EQ'd" discs you guys are always speaking of.


Thanks Again to all,

:-jon

[Steve Hoffman]

Smile EQ: Turning up the top of the treble and the bass, leaving a hole in the crucial midrange.

Nothing to do with clipping.

Digital compression on some newly remastered CD's, EVERYTHING to do with what you are talking about.

[David R. Modny]

On the subject of digital clipping, here's something that's a bit unrelated but it still might interest those who make their own A/D transfers using a lower-end computer soundcard.

One of the versions of the Ensoniq PCI card (the latter one made by Creative), actually was miscalibrated and clipped at a level quite a bit lower than 0db full scale (i.e. + 32767 samples, 16 bit). This was later traced to a bad chipset, and from what I've been led to believe is something that's not uncommon in other Creative cards.

Thus, one's "clip" meters wouldn't light and the user wouldn't even know their transfer was badly, hard-clipped unless they analyzed the waveform...or more obviously just listened for the obvious distortion.

The bottom line...don't *always* assume that a signal is free of clipping, just cause the signal didn't peak at full scale or the meters didn't light! Check the visual waveform afterward! Luckily hard digital clipping is pretty easy to spot upon listening even if one doesn't have access to waveform analysis....very ugly sound!:eek:

[Grant]

Originally posted by David R. Modny
On the subject of digital clipping, here's something that's a bit unrelated but it still might interest those who make their own A/D transfers using a lower-end computer soundcard.

One of the versions of the Ensoniq PCI card (the latter one made by Creative), actually was miscalibrated and clipped at a level quite a bit lower than 0db full scale (i.e. + 32767 samples, 16 bit). This was later traced to a bad chipset, and from what I've been led to believe is something that's not uncommon in other Creative cards.

Thus, one's "clip" meters wouldn't light and the user wouldn't even know their transfer was badly, hard-clipped unless they analyzed the waveform...or more obviously just listened for the obvious distortion.

The bottom line...don't *always* assume that a signal is free of clipping, just cause the signal didn't peak at full scale or the meters didn't light! Check the visual waveform afterward! Luckily hard digital clipping is pretty easy to spot upon listening even if one doesn't have access to waveform analysis....very ugly sound!:eek:

Actually, all Creative cards I have seen or used do the same thing. I had that Ensoniq card years ago and it is horrible! But, I bought it at a time when I didn't know any better, and there really wasn't much of a choice for quality sound yet.