FCP Audio level adjustments

[J.Dean]

I am a novice editor in FCP and had a question about adjusting the audio for a segment I'm working on. There's only primary audio that I am working with and I need it to be at or around 12 db, but I'm not sure what in the audio window along the time line I'm supposed to be checking: is it the bar itself that raises and lowers that I should be looking at to see where it peaks, or is it the yellow line that is above the bar and raises or lowers with it. In other words, which is the true measure of the audio: the green bar or the yellow line above it.

Thanks

 

[Lebowski]

I am a novice editor in FCP and had a question about adjusting the audio for a segment I'm working on. There's only primary audio that I am working with and I need it to be at or around 12 db, but I'm not sure what in the audio window along the time line I'm supposed to be checking: is it the bar itself that raises and lowers that I should be looking at to see where it peaks, or is it the yellow line that is above the bar and raises or lowers with it. In other words, which is the true measure of the audio: the green bar or the yellow line above it.

Thanks

a bit of yellow is ok.... you DO NOT want red. The "peaking" is the high point on the audio (the loud part), so keep you peak level in safe range.

 

[ppc_michael]

The audio bars display the audio level at any given moment. The yellow line shows you the peak that recently occured--the loudest points in the audio. It lags behind a bit so you can see the highest point.

You should be watching both, but the yellow line will show you the peaks, so that's what you won't want going past the -12dB mark (or whatever you want).

 

[ChemiosMurphy]

if you see red you're dead.

That means clipping. The waveform is physically chopped off at that point and you get some horrible sound. You can't unclip a clipped clip.

The sweet spot for DIGITAL audio is -12 DB. Shoot for that always.

Here's my professors textbook on Audio. I'm a film major. Read this..

 

[Poeben]

Be careful using terms like always. Traditionally, the reference level for analog audio is 0VU. There are a number of digital audio reference standards in use today, most commonly -20dBFS and -18dBFS. That's not to say that -12dBFS doesn't exist as a standard, as I do see it frequently (mostly from major motion picture companies.) However, if a client doesn't provide a spec sheet it is assumed the reference level is -20dBFS. They could even spec -13dBFS for superstitious reasons and, as long as you know what it was referenced to, not really matter.

Also, don't overlook the difference between peak and RMS levels as both are very important. To the OP, keep your peak levels well out of the red. Your RMS levels should average at or near your reference level, be it -20, -18, or -12. If you ignore the RMS level you may end up with audio that, while not clipping, is very low in level. My default specs are -20dBFS reference and -10dBFS peak level.

 

[ppc_michael]

Welllll he said he wanted (-)12dB so I think that's why we're all saying 12.

 

[AviationFan]

The sweet spot for DIGITAL audio is -12 DB. Shoot for that always.

Here's my professors textbook on Audio. I'm a film major. Read this..

I took a look at the "textbook". It does contain a lot of helpful information, even though it mostly lacks the broader scope, details and rationales I would expect from a real textbook. If you are interested in those, I can recommend the audio books by Jay Rose. You simply cannot cover a topic such as "audio for DV" in 12 pages.

As for -12dB (or -12dBFS, which I assume we all mean) being "the sweet spot for digital audio", it all depends on what you are doing. Different conventions are used in different phases of production (recording, mixing, mastering) and for different circumstances. For example, pop music CDs are typically mastered to peak at 0dBFS, whereas lower levels are used for video/film, and the actual levels depend on where the final result will be seen/heard (movie theater, TV, VHS tape).

I would agree, though, that for RECORDING audio into a DV camcorder, -12dBFS is a good limit to shoot for in many cases.

- Martin

 

[digigal]

Thanks for the references

Chip and Martin -

Thanks for the reference materials. Martin, you're right, 12 pages does not do it justice, but a good place to start. I did not major in film but have been thrust into video production due to the educational benefits of creating video. I was actually thinking of taking a course in audio production (heard of a local instructor who is very good in this regard).