Thread: How to prevent clipping when recording audio in-camera...

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  1. #1 How to prevent clipping when recording audio in-camera... 
    Senior Member Dave Draper's Avatar
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    If recording audio in-camera, via a wireless lav receiver plugged into the V-Lock I/O Expander, does the DSMC2 offer any kind of AGC or digital limiters to prevent clipping at all?

    If not, what would you say is the lowest recommended gain to set the pre-amps when working with talent whose voices fluctuate a fair amount in volume?

    We're talking for small, unscripted videos, such as vlogs, or documentary work, where you may not have a dedicated sound guy, and where things are more-often-than-not very candid and spontaneous.
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    This may not be the answer you want, but the truth is this is why sound mixers exist. Hire an experienced sound person, and you won't run into level problems.

    Figuring out gain staging (the relationship of multiple steps in the audio chain) and how they affect each other is critical, and the problem is that you can clip or distort early on -- even at the microphone itself -- and then you'll never be able to eliminate that distortion, even if you turn down the level later on, like in the camera.

    A limiter/compressor is not always the answer, either, because it tends to dynamically affect the dialogue in unexpected ways that you may not like, particularly if there's a lot of background noise in the area.

    If it were me, I'd do two things: have a good, reliable wireless lav placed carefully on the talent, make sure the levels are optimal at every step of the signal path, and record that on one channel. And then use an overhead boom mic in the event that that sounds better, and record that to the second channel. Ideally, you need a boom op as well.

    Without these things, it can all go to hell very quickly. Heck, it's hard when you do have a great sound person. My contention is that the camera operator and DP already have a tough enough job without having to also worry about sound.

    I don't dispute that there are situations where it's not possible to have a sound person, like when you're in a war zone or recording under dangerous conditions (like with police on the street). But the reason why documentaries and good reality shows have great sound is generally because there was a sound person right there on the set, riding levels, moving around the mics when necessary, even using multiple mics when necessary. Anything less will be a big compromise.
    marc wielage, csi colorist/post consultant daVinci Resolve Certified Trainer
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    Senior Member Dave Draper's Avatar
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    Quote Originally Posted by Marc Wielage View Post
    This may not be the answer you want, but the truth is this is why sound mixers exist. Hire an experienced sound person, and you won't run into level problems.

    Figuring out gain staging (the relationship of multiple steps in the audio chain) and how they affect each other is critical, and the problem is that you can clip or distort early on -- even at the microphone itself -- and then you'll never be able to eliminate that distortion, even if you turn down the level later on, like in the camera.

    A limiter/compressor is not always the answer, either, because it tends to dynamically affect the dialogue in unexpected ways that you may not like, particularly if there's a lot of background noise in the area.

    If it were me, I'd do two things: have a good, reliable wireless lav placed carefully on the talent, make sure the levels are optimal at every step of the signal path, and record that on one channel. And then use an overhead boom mic in the event that that sounds better, and record that to the second channel. Ideally, you need a boom op as well.

    Without these things, it can all go to hell very quickly. Heck, it's hard when you do have a great sound person. My contention is that the camera operator and DP already have a tough enough job without having to also worry about sound.

    I don't dispute that there are situations where it's not possible to have a sound person, like when you're in a war zone or recording under dangerous conditions (like with police on the street). But the reason why documentaries and good reality shows have great sound is generally because there was a sound person right there on the set, riding levels, moving around the mics when necessary, even using multiple mics when necessary. Anything less will be a big compromise.
    Totally respect what you're saying. Sound Recordists are invaluable. It's just a shame that clients often overlook their importance, and rarely have enough in their budget to hire one.

    We often run into these situations, where clients expect us to be both the Camera and Sound Department, on a minimal budget, or as a one-man crew, and frequently get asked questions such as; "If these people on YouTube, shooting on cheap equipment can do it, why can't you?".

    Regarding recording two channels of audio, in-camera; could that be done with a Wooden Camera A-Box plugged into the 3.5mm jack socket in the back of the V-Lock I/O Expander? Or were you referring to using a separate multi-track field recorder?
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    Not sure about DSMC2, but DSMC1 limiters were... poopies.

    On the flipside, some of the prosumer Sennheiser lavs (AVX, I think), have surprisingly rad AGC. Is it the best? Obviously not. Does it rock your socks off when you got no other options? Absolutely.

    I also tend to be conservative on my in-camera gain (tend to avg ~3db lower in order to save on the high-end) and if it needs to be aggressively boosted after, I cross my fingers and use noise reduction.
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    Quote Originally Posted by Dave Draper View Post
    Regarding recording two channels of audio, in-camera; could that be done with a Wooden Camera A-Box plugged into the 3.5mm jack socket in the back of the V-Lock I/O Expander? Or were you referring to using a separate multi-track field recorder?
    I would go with one of the small Sound Devices mixers and bolt it to the side of the camera. But the tough reality is that a lot of sound issues requires that you actually adjust the level as it's recording -- it's not always a "set it and let it go" operation.
    marc wielage, csi colorist/post consultant daVinci Resolve Certified Trainer
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    Quote Originally Posted by Dave Draper View Post
    If recording audio in-camera, via a wireless lav receiver plugged into the V-Lock I/O Expander, does the DSMC2 offer any kind of AGC or digital limiters to prevent clipping at all?.
    Turning on AGC is a very very very poor approach to dealing with clipping, unless you don't care about that audio being used in the final end result... (I'll now and then set the camera's scratch mic to auto, because all it needs to do is provide a back up track as a last resort option for syncing)

    Quote Originally Posted by Marc Wielage View Post
    I would go with one of the small Sound Devices mixers and bolt it to the side of the camera. But the tough reality is that a lot of sound issues requires that you actually adjust the level as it's recording -- it's not always a "set it and let it go" operation.
    Or a Zoom F4/F8/F8n, which are also extremely compact, but a little bigger.

    And yes, it is not a "set and forget" set up. Just like neither your ISO or F stop is a "set and forget" situation.

    Quote Originally Posted by Dave Draper View Post
    Totally respect what you're saying. Sound Recordists are invaluable. It's just a shame that clients often overlook their importance, and rarely have enough in their budget to hire one.

    We often run into these situations, where clients expect us to be both the Camera and Sound Department, on a minimal budget, or as a one-man crew, and frequently get asked questions such as; "If these people on YouTube, shooting on cheap equipment can do it, why can't you?".

    They have budget to hire a RED camera and camera crew... they've got budget to hire a sound recordist.
    http://IronFilm.co.nz/Sound/ (Sound Recordist based in Auckland, NZ. Happy to travel too)
    https://www.youtube.com/c/SoundSpeeding
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