Audio rates 44100/32 vs 48000/6

Hello,

Calling all audio experts.

I'm doing a bit of quality control for a project and I just got the first batch of dailies.

I see the audio has been recorded at a sample rate of 44,100/32 bit.

Now I thought the minimum one should record audio is at 48,000 khz..

My question is this, by it being recorded at 44,100, is that bad?

How big of a quality difference are we looking at vs 48,000?

Does the fact that it was recorded at 32bit, make the 44,100 superior to a 48,000 recorded at 16 or 24 bits?

Thank you

It depends entirely what your sound people want and if they would benefit from using 32bit Floating Point Audio.

You could convert to 24Bit 48KHz but to be fair you won't get a higher quality just because you up the sample rate - it's already recorded at the lower rate and you might also find you limit the dynamic range of what you recorded so much they can't get the best out of the files.


The Audio Sample Rate is a akin to "Frames Per Second".

The Audio Bit Depth is akin to the "Resolution" or number of Pixels in an image.


So if you have higher "sample rate" in Hz you are capturing more temporal detail of the analogue sound's "waveform" per second - a sample in time like digital slices or frame of video.

If you have a higher "bit depth" you sample more of the amplitude of the analogue waveform per sample - or the amount of detail vertically on a waveform.


Here's a nice article on 32bit Floating Point Audio that might help you decide: [www.askaudiomag.com]



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

Thank you, I actually discovered another issue, it's solvable but just inefficient.

Typically, I'm used to getting 1 audio file per take, and that file will included all the audio tracks recorded for that take, so when I drop it in the timeline, all the tracks are connected.

This production sound mixer has been recording each track separately, so for scene 1 take 1, I'll have 4 files:

001Take1 - boom
001Take1 - lav
001Take1 - lav2
001Take1 - lav3

So now I have to select all four files, bring them into the timeline and connect them for each take. Not the end of the world but unless they are using a h4n, I've always received one audio file, with all audio tracks included in it.

When I asked the mixer, he said his mixer/recorder doesn't have the ability to do that?

Never mind, investigated it, mixer is using some mickey mouse setup so it's a limitation of his equipment.

hopefully he can change to 48k, though?

as for lining up & linking the mono files, FCP is pretty clumsy at that.
i reckon some other app might help out there, but i don't know what it would be!

or maybe sequence liner could help.


nck

Sound Devices's Wave Agent can combine multiple tracks into one polyphonic file (and vice versa). Very handy bit of software, that one.

ak
Sleeplings, AWAKE!

Do you have scratch sound recorded on the camera?

If so then FCPX or PluralEyes is your beast of burden for linking files.

If not then making sure the sound and camera TC is jam-synced means you can do it via TC and an app like

Sync-N-Link [assistedediting.intelligentassistance.com] or sequenceLiner [www.spherico.com]


Otherwise if you have no matching sound or TC go through and put a marker on the Video Clapper clap and then on the audio files then it's really easy to drag and sync files marker to marker.



For instant answers to more than one hundred common FCP questions, check out the LAFCPUG FAQ Wiki here : [www.lafcpug.org]

I don't think sync is his problem. The start/stop points on all those files probably match. I think he's simply annoyed with the fact that the multiple tracks aren't linked by default. That's how I ordinarily edit sound, myself -- everything unlinked like film tracks, since I almost never cut audio at the exact same point as video.


www.derekmok.com

Derek hit the nail on the head, just a bunch of unnecessary extra work.

Andrew, thanks for naming that program, I'll look into it.

Ben, this has been another bone of contention. He can't jam sync TC (doesn't have the equipment), so I requested a scratch track into camera. The camera, requires a line level input, so I guess it's more complicated than usual to get a feed into the camera that actually has a decent signal strength.

Nick, I let him know as soon as I discovered it to start recording at 48k from now on. I was actually given what I consider a ridiculous reason as to why he recorded at 44.1k.

Do I need to convert all these files to 48k, not that it will add quality, but to be consistent with the rest of the files I will get from now on? It seems FCP can handle 44.1k and 48k files in the same timeline and not require rendering.

Bottom line, I'm not sure how experienced he is with film workflow, he's using an unorthodox setup (not your typical sound device recorder, which can't record polyphonic WAV files). He did say he could export OMF's and that will bring in all the files from 1 take. I guess we will see.

Joe
You could try and do something for your own benefit and get, at the very least, a mic on the camera, the simplest kind that won't bother the camera ops and doesn't tax your inexperienced audio op. A small shotgun pointing forward will get the slate clap and help with PluralEyes type syncing. Almost any mic will do and you might have to get a small one to get it past the crew who don't want any more complication than they already have.
If you have a good music rental store in your area you can usually get a reliable hardy one for very little weekly cost. Audio post rental place might have more specific solutions but I find that usually means a higher cost.

What is this person using anyway? A DAW? Some old piece of gear?

ak
Sleeplings, AWAKE!

Andrew,

I have explored this and done this with other productions. I'm dying to get a signal into the camera!

However, because the camera (ALEXA) has a line level input only, simply attaching a mic to the xlr input won't work. Anyone experienced with this camera please chime in. I'm not familiar with audio/line level, etc... but from what I understand because it's line level, the signal from the mic is too low.

I was told it needs "a inline mic pre amp that receives low z mic level and outputs line level signal" that might as well be Greek to me, so I asked him to find it online and I can talk to production about getting it. This has been rather frustrating as he has not given me the an answer on the definite part needed, even though we've spoken multiple times about it. I'm going to have to take the bull by the horns are call rental companies myself.

He's using a mixer, but the mixer can't record, so mixer is connected to a laptop where he is recording via a DAW.

> I was told it needs "a inline mic pre amp that receives low z mic level and outputs line level signal" that might as well be Greek to me, so I asked him to find it
> online and I can talk to production about getting it.

You may need a preamp unit in the chain.

[www.bhphotovideo.com]



Microphones, guitar signals -- pretty much all audio signals have an impedance rating:

[whirlwindusa.com]

[www.mediacollege.com]



In music situations, we boil it down to: Low-impedance signals are microphones (frankly, I've never seen a microphone that is high-impedance, in any recording/live setting); high-impedance signals are guitars. Low-impedance signals require a higher boost to be heard.

Low-impedance signals carry better over longer cables (which, in our film-production situations, is pretty much all the time), and are less prone to interference.

If you ever get a chance, get a close-up look at a mixing board in a music club. You will see that every channel has a knob that says "Line/Mic". Most people mistake it for a volume knob, which it is, in some ways, but using it as a pure volume knob will get you into trouble. The proper way to use this knob is to leave it low on a guitar input and turn it up on a vocal input.

Most mixers and field recorders (including ultra-portable units such as the Zoom H4n and the Tascam DR-60D) have a microphone preamp in the chain, so if your audio is going through a mixer or a recorder, this is most likely going to be a non-issue. I've never seen a situation where the camera would set up its own microphone, with no preamp, when there's a dual-system sound recorder in the mix, so I think your recordist may be creating a problem where there is none. If you're going with the camera-mounted microphone, then check your levels, and it might be necessary to add a Beachtek unit (such as this [www.bhphotovideo.com]) into the mix.

Since you're not using the camera audio as your main audio, the signal doesn't have to be pristine, just high enough for sync purposes. However, given how inexperienced your recordist is, it may be wise to have this option available and try to get as much usable audio as possible at the camera stage.

> He did say he could export OMF's and that will bring in all the files from 1 take. I guess we will see.

Not relevant to you. Final Cut Pro can't import OMFs.


www.derekmok.com

Derek, thanks for the info.

Quote
Not relevant to you. Final Cut Pro can't import OMFs.

Right, soundtrack pro can, but what am I supposed to do with that? Round trip to FCP I guess?

with Automatic Duck you can get those OMFs into FCP


nick