on-set audio recorded too low, raising volume = hiss

Hi all - on a tight deadline and need some swift advice . it's been a long time since i've delt with audio recorded with such variants in volume . .

the on-set audio is recorded too low and raising the volume in FCP to make it match the properly recorded audio results in hissing and noise that brutally disrupts the edit / performance of the actors, with monologues being constructed from various takes

is there any technique or filter setting recommended to (at least to some degree) reduce the noise levels?

many thanks,
WM,

Not sure about within FCP (maybe a high/low pass filter or EQ?), I've used noise reduction in Soundtrack Pro and Audition before, it helps a little but if you go too much it makes the voice sound weird.

Low audio is a nasty problem, I'd love to hear others solution to this.

There is an old trick to raise the level of too-soft audio that may help. Double the audio tracks (copy to a new track). This raises the overall level without raising the noise level as much as simply raising the gain does. May or may not help in your case.

Thanks Joe, Scott, I've tried both your suggestions before to varying degrees of success, I guess it's going to have to be a combination of the two again, i'll also continue hunting and searching online / other audio apps.

The script is good the footage absolutely incredible ( they got lucky with a very good DP to shoot it ) cinema-grade DP, and a separate guy for the sound but it's just such a killer because the audio levels are SO variable to the point certain scenes have had to be cut because you can't hear whats going on without boosting it, the hiss is almost even stronger than the dialogue . .

Sideways thinking - if the scene is pivotal and you really can't fix the sound, how about leaving it low and adding some subtitles in those areas? A bit distracting, yes, but better than having the whole thing not make sense for lack of a scene.

Another trick is to nest the low audio region, name the nest after the speaker and append "audio boost" so it appears that way in the Browser, then in the Timeline you have another 12DB you can raise on the nest clip! You can also apply an EQ filter to the nest to help reduce hiss. This has helped me time and again, and allows me to keep to my track scheme, such as voice, music, effects without unduly adding extra tracks for isolated audio problems.

Later, if/when you get into pro audio post, you would de-nest the clip, so the mixer can grapple with the original signal.

- Loren

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> Another trick is to nest the low audio region, name the nest after the speaker and append "audio boost" so it appears that way in the Browser, then in the Timeline you
> have another 12DB you can raise on the nest clip!

That's a very inefficient way to do it, left over from FCP history. Since FCP6 or so there has been a Gain filter you can add to an audio clip to raise levels beyond 12dB. You can also use AUDynamicsProcessor, though that tends to come with compression by default. Besides, if the audio level is so low that 12dB can't get it to audible levels, then chances are your noise floor would be too high anyway and you'd need far better tools than FCP has. Soundtrack Pro's combination of noise printing with reduction, noise gates, sweepable parametric EQ, channel EQ and compressors would do a better job.


www.derekmok.com

WM, curious, is the low audio due to a inexperienced sound mixer or just the locations were audio nightmares so he had to keep it low?

Forgive me, Derek, I beg to differ- the Gain Adjust in FCP7 does not add anything outside the scale of the clip gain. Try it. Try it Relative, try it Absolute. You will not achieve what you describe. The Gain Adjust is useful for lifting overall gain set in the entire Timeline with respect to preserving previously set clip levels- the Relative setting. very valuable for that. Absolute will top it out at 12DB or anything up to it, but not beyond, which is the need described here.

Then try nesting the troubled clip and boosting the gain controls on the nest.

For me, it's faster than diddling with an audio filter, especially the ones in FCP7 with the crappy interface, and especially if you're only doing a scratch mix.

- Loren

Today's FCP 7 keytips:
Copy clip Attributes with Command-C
Paste selected Attributes with Option-V
Remove selected Attributes with Command-Option-V !

Your Final Cut Studio KeyGuide™ Power Pack.
Now available at KeyGuide Central.
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> Forgive me, Derek, I beg to differ- the Gain Adjust in FCP7 does not add anything outside the scale of the clip gain.

Not the normal Level command, Loren...Gain is an audio filter that appeared around FCP6 or so. It doesn't have the "Relative" or "Absolute" option (achieved by Modify - Levels, or OPTION-COMMAND-L -- not a filter), nor does it have the +12dB limitation, either on its own or in combination with the 12dB Levels boost (I just checked). Check your Audio Filters - Final Cut Pro menu. It just doesn't get used very often because as I mentioned, boosts beyond 12dB tend to mean the original sound was too low/noisy to begin with.


www.derekmok.com

> is the low audio due to a inexperienced sound mixer or just the locations were audio nightmares so he had to keep it low?

It can be all of the above. What I've encountered a lot is that it's an inadequate recordist or inadequate equipment. Levels are levels, but the presence, richness and clarity of the signal are up to how good the microphone is, how well it was used (eg. positioning, correct settings), the electrical systems at work in the surroundings (eg. how a building was wired, what radio signals are in the area), and what other gadgets are in the signal path. Hell, the vocal timbre and volume of the subject can make a massive difference.

One thing that they don't teach you in general film school, for example, is how important a preamp is. A really good microphone with the right frequency response and neutrality, 48V phantom power and a great preamp, recording dialogue at -24dB, will get a much better signal than a cheap, non-powered $20 mic with no preamp even if you make the latter's level the same, -24dB. Remembering that sound isn't just sound; when it goes into a microphone, it gets translated to electricity, and the strength of that electrical signal matters a great deal. Boosting the level of a weak signal is not the same as getting a strong signal to begin with. One recordist opined that he'd rather use a cheap-ish mic with a great preamp than a $1000 mic with a bad preamp.

The right cables also matter. Put a high-impedance link into your signal chain, for example, or set the channel to Line instead of Mic level, and your recording quality will plummet.

I just did an interview shoot where the venue couldn't shut off all of its air conditioners (I heard, I asked, I was politely told it was not possible). I also had a lavalier that was a little boxy-sounding, and a shotgun mic that was on the cheap side. So I ended up running five audio sources -- shotgun mic, lavalier, camera A (with top-mounted video microphone), camera B (camera mic, sync reference only), and a Zoom H4n. The Zoom actually got the best sound because the on-board microphones had the best attributes -- right pickup pattern, right combination of directional pattern yet picks up enough outside of that pattern not to make things sound dead, and it was in the best position (within one foot of subject, low on a table, outside of frame, pointed at the mouth). The sound I got was better than one high-budget show I had where there was a full crew, with every subject lavaliered plus a boom, and all levels were supposed to be at -20dB or so but were so noisy that they sounded like ambient mics.


www.derekmok.com

[Not the normal Level command, Loren...Gain is an audio filter that appeared around FCP6 or so.]

Noted!

- Loren

Today's FCP 7 keytips:
Copy clip Attributes with Command-C
Paste selected Attributes with Option-V
Remove selected Attributes with Command-Option-V !

Your Final Cut Studio KeyGuide™ Power Pack.
Now available at KeyGuide Central.
www.neotrondesign.com

Interesting stuff Loren, and thanks Derek great info and perspective on sound recording, thanks guys,

WM,