FORUMS: list search recent posts

The most important audio-related question in the world!

COW Forums : Audio Professionals

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Shane Copland
The most important audio-related question in the world!
on Nov 21, 2013 at 5:49:52 am

If you have to choose between clear audio that has low volume, and average quality audio but with normal volume levels... which do you choose, and why?


Return to posts index

Peter Groom
Re: The most important audio-related question in the world!
on Nov 21, 2013 at 12:34:22 pm

2 answer this , I need to ask more questions.

What is the noise floor like on the lower recording. And how low is it exactly.
What makes the average recording average. Noise / distortion / noise floor high?

Peter

Post Production Dubbing Mixer


Return to posts index

Shane Copland
Re: The most important audio-related question in the world!
on Nov 21, 2013 at 3:54:06 pm

The lower recording is very clear but peaks at about -30db. The average recording is from the internal mic of the camera, so it comes with the quality you'd expect (slight echo, a little tinny).


Return to posts index


Richard Crowley
Re: The most important audio-related question in the world!
on Nov 21, 2013 at 7:14:30 pm

Why do you have to choose? I don't think you are asking the right question.

If I had such a problem, I would identify all the involved equipment, how I was setting it up, interconnecting it, and using it. It might even be useful to post a sample clip somewhere so that people can hear what you are trying to describe.

You have asked an unanswerable question. There doesn't seem much point in discussing it.


Return to posts index

Shane Copland
Re: The most important audio-related question in the world!
on Nov 21, 2013 at 7:23:34 pm

Everything has already been recorded, and is as descrbed above. So now what im trying to determine is what audio should I focus on improving? Clear audio with low volume or audio with a lot of background noise but normal volume levels?


Return to posts index


Peter Groom
Re: The most important audio-related question in the world!
on Nov 21, 2013 at 7:53:54 pm

Well based on what you say and not having heard anything I d go for the low clean audio and boost.
Can you post a clip so we can have a listen . That way it's less hypothetical
Peter

Post Production Dubbing Mixer


Return to posts index



Richard Crowley
Re: The most important audio-related question in the world!
on Nov 21, 2013 at 9:38:17 pm

You don't really have "clear audio with low volume". Because if you did, when you boosted the level, you would still have "clear audio".

What you have is audio with poor signal-to-noise ratio, and by listening at a low level, you fool yourself by also reducing the noise level.

So your real question is, "how do I reduce the noise in my recording"? As Mr. Groom says, nobody can offer a practical answer to that question without hearing it. This isn't a philosophical debate, it is simply a common technical question.


Return to posts index

Craig Alan
Re: The most important audio-related question in the world!
on Nov 25, 2013 at 5:51:05 pm

Richard,

This gets to the core of a thread I was having with Ty about calibrating the mixer to the camcorder and what base level would usable. Ty would not answer directly and if I am understanding your comment correctly explains why.

If you were in a sound proof room and recorded any sound that registered at the lowest possible point on an audio meter, if there was no competing sounds at all (including camera noise), are you saying in theory, that if you then boosted that sound in post the result would be perfectly acceptable?

Craig

Mac Pro, macbook pro, Imacs (i7); Camcorders: Panasonic AG-HPX170/AG-HPX250P, Canon HV30/40, Sony Z7U, VX2000, PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.


Return to posts index

Chris Conlee
Re: The most important audio-related question in the world!
on Dec 6, 2013 at 7:26:17 pm

[Craig Alan] "If you were in a sound proof room and recorded any sound that registered at the lowest possible point on an audio meter, if there was no competing sounds at all (including camera noise), are you saying in theory, that if you then boosted that sound in post the result would be perfectly acceptable?"

Yes and no. ;)

As usual there are other questions that need to be answered first. Primarily what bit depth is your recording? If the recording was low and you boost it, what you are technically doing in the digital domain is throwing away bits at the top and padding with zeros at the bottom. When recording in 24 bits, you have a theoretical 144 dB of dynamic range, vs ~96 dB of dynamic range for 16 bits.

Basically for every 6dB of gain applied, you've just lopped off a bit from your recording and reduced your dynamic range. In the theoretical world of which you speak, you could basically apply 48dB of gain to your 24bit recording and essentially leave yourself with the equivalent of a 16bit version.

However, we don't live in a perfect world and there is always noise present, no matter what. Even the electronics themselves present low-level noise, so any gain raises this noise too.

I think the answer to the OP's question is: apply the needed gain to the "quiet" recording and see if it sounds better than the "louder" recording. If it sounds better, then it IS better.

Chris Conlee


Return to posts index


Craig Alan
Re: The most important audio-related question in the world!
on Dec 7, 2013 at 6:03:34 pm

Thanks. Theoretically, I follow you; but actually it’s a little over my head. But your post did help.

In practice, I still like to hear (monitor) what I'm recording while leaving enough headroom to not clip. What I have experienced with very limited skills in post is that with clean sound (not distorted or noisy) the levels can be adjusted to a degree. Distorted sounds remain distorted and low-level clean sound can be raised, but more noise is added.

However, I have not used a dedicated recorder or a laptop to record sound as others have suggested would be a big improvement and allow for lower/safer recording levels. This view is in contradiction to some of the audio pros on this forum (the lower levels not the advantage of a better recording device), who advocate recording in the yellow zone of the mixer’s meter while carefully monitoring for unwanted noise and for spikes that would necessitate leaving more headroom.

Hearing is believing, so I will experiment with all these approaches and see what works best. We will still use camcorders as the audio recorder in many shoots, where simpler is better, and I will try other approaches as we get the chance. I do have a firewire mixer, Mackie Onyx 1220i, but the only laptop I have is a few years old and I’m not sure if its good to go with the new FCPX, (FCP is listed, on Mackie’s site as compatible with the mixer). I could use one of our Imacs, however, to test it out.

Mac Pro, macbook pro, Imacs (i7); Camcorders: Panasonic AG-HPX170/AG-HPX250P, Canon HV30/40, Sony Z7U, VX2000, PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.


Return to posts index

Chris Conlee
Re: The most important audio-related question in the world!
on Dec 7, 2013 at 6:47:20 pm

In practice you always want to get the best signal to noise ratio you can. Get the microphone as close to the subject as humanly possible, and try to keep it pointed at the speaker's mouth at all times. Eliminate all background noises that you can, such as refrigerators, etc. Then, if recording in 24bit, I think you can safely shoot for the low-yellow on your meter, which will probably be something like -20dB ish. You actually have a lot of headroom at 24 bit to adjust gain. The quality of your recording and the signal to noise ratio are your two biggest concerns, in my opinion.

Also, depending on your recording gear, you could also add some protection by recording thru a limiter. But be careful with that, as some limiters can add funky noise and/or artifacts to your recording. I've especially noticed noisy recordings from H4 recorders when the limiter is engaged.

Chris Conlee


Return to posts index

Craig Alan
Re: The most important audio-related question in the world!
on Dec 7, 2013 at 11:20:16 pm

[Chris Conlee] "In practice you always want to get the best signal to noise ratio you can. Get the microphone as close to the subject as humanly possible, and try to keep it pointed at the speaker's mouth at all times. Eliminate all background noises that you can, such as refrigerators, etc. "

Yes to all. That is what I teach daily and repeatedly. Our sound devices mixers have quality limiters and I keep them enabled. Our CanonHV40s have only 16bit audio, The Panasonic HPX250s use AVC-Intra 100/50, DVCPRO HD, DVCPRO50: 48 kHz, 16-bit, 4-channel
DVCPRO/DV: 48 kHz, 16-bit, 2/4-channel switchable.

[Chris Conlee] "I think you can safely shoot for the low-yellow on your meter, which will probably be something like -20dB ish. "

We calibrate our cameras at 0 tone out mixer to -20 on our camcorders. So -20 levels is just touching the yellow on the mixer (0) and here's where the debate begins. If you are suggesting 0 (mixer)/-20 (camcorder) levels as an upper limit, you are in the camp that suggests keeping the levels conservatively low. The other camp was suggesting in the yellow or just kissing the red zone which is +12 on the mixer and roughly -12 -6 on the camcorder (again depending on how much headroom you need). As a general rule I aim for a range between 0 +4 +8 on mixer which if calibrated to -20 on the camcorder should not hit the 0 on the camera.

So bottom line: is there anything wrong with the practice of recording as high as possible without clipping as opposed to recording safely lower levels and boosting in post when needed. My own practice is to aim for -12 on our HPX250s (+4ish on our SD 302s).

I do not prefer to use auto gain control on camcorders or built in limiters on camcorders. I really wish the camcorder companies would invest a little more in the audio components. Quieter preamps, 24 bit, better headphone amps and so forth. I'd bet prosumers would be willing to spend extra for a camcorder that had better sound built in. That said when miked correctly I am pretty happy with the sound we record on our panasonic cams.

Mac Pro, macbook pro, Imacs (i7); Camcorders: Panasonic AG-HPX170/AG-HPX250P, Canon HV30/40, Sony Z7U, VX2000, PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.


Return to posts index


Chris Conlee
Re: The most important audio-related question in the world!
on Dec 8, 2013 at 12:24:10 am

[Craig Alan] "So bottom line: is there anything wrong with the practice of recording as high as possible without clipping as opposed to recording safely lower levels and boosting in post when needed. My own practice is to aim for -12 on our HPX250s (+4ish on our SD 302s)."

I don't think there is anything "wrong" with getting the meatiest signal you can possibly get. I think the camp which advocates on the conservative side does so only with protection in mind. I can't think of a reason why low levels would be "better" than higher levels. Particularly since you're recording at 16 bit, I would say the higher the level (without clipping) the better. You have much more latitude with 24 bit audio, in this regard.

Chris Conlee


Return to posts index

Craig Alan
Re: The most important audio-related question in the world!
on Dec 8, 2013 at 2:19:06 am

Thank you very much.

This has been very helpful.

Mac Pro, macbook pro, Imacs (i7); Camcorders: Panasonic AG-HPX170/AG-HPX250P, Canon HV30/40, Sony Z7U, VX2000, PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]