Questions about sound in Red One

[GlennChan]

If you need to record surround ambiances, I think a better idea would be to record them separately. A laptop with a decent audio interface is very cheap nowadays. In addition, you can take a mobile recorder to many different locations and record different ambiances.

2- For the few people who need to record a stereo mic (i.e. perhaps in documentaries), I think a reasonable workaround would be to use a field mixer than supports it (i.e. M/S headphone matrix, linked gain, linked limiters). You'll likely have a sound guy with a field mixer anyways.

 

[Trevor Meier]

Things I'd like to see on the input side:
- analog input limiters
- flexible options for digital input (USB, AES, ??)
- remote control of input level & remote level meters *

Options for headphone/output monitoring:
- flexible 4>2 channel downmix (all channels to stereo, all channels to mono, or separate channels/channel pairs to mono left, mono right)
- channel monitor: selectable stereo ch 1&2, 3&4 stereo mix; or mono ch. 1-4
- left ear 4>1 channel downmix; right ear, selectable channel or pair of channels (e.g. for using a channel as audio input for set radios)


* Scenario: In keeping with the indie nature of the camera, allowing a boom op to have remote control of audio levels on the camera reduces the need for a recordist or a field mixer.

 

[Peter Richardson]

I'm curious about a comment Stewart made:

The camera can suppress any active cooling (and hence sound) during a take.

How would the supression of active cooling work on a documentary, where the camera is almost always constantly rolling? Will there be overheating issues if the active cooling is left off? If you could elaborate on this that would be great as I principally plan to use my Red for doc work (made a reservation on Monday). Thanks,

Peter

 

[Steve Freebairn]

Can you record audio while you are over and undercranking? That is what I'd really like. (As long as it stays sync)

 

[David Fairbanks]

To keep it in sync you would have to sample at greater rates or it would have to interpolated to the greater rates. If you're shooting at 48fps that would mean recording the audio at 96KHz and so forth.

 

[GlennChan]

Another possibility:
What about automated syncing with .BWF files? This would enable 4+ channels of *high quality* audio recording, and a reasonable workflow. A Sound Devices recorder is only $4k, which is a reasonable price. Automated syncing with .BWF files would also improve the workflow where >4 tracks are desired. I think it's a better approach than recording better-than-normal audio onto the camera. In my opinion, 2 channels of really good analog inputs (with good soft limiters) is likely the best approach. Anything more than 2 channels can go with double system sound, with automated syncing of .BWF files. Just make sure that the timecode clocks don't drift and that the process is mostly foolproof (which I believe are challenges with Keykode, since TC does end up drifting and sync is off).

In keeping with the indie nature of the camera, allowing a boom op to have remote control of audio levels on the camera reduces the need for a recordist or a field mixer.

Trevor, I don't believe that feature will really solve anything. If you have the controls remote, you'll still need someone to operate those controls!

2- Also, you really only need to set the levels on the camera ONCE. If you're using a field mixer, you mix in the field mixer and calibrate the camera to tone.

3- Also check out
http://www.sonosax.com/BD1/SX-BD_InfosheetE.html
A mixer that fits onto a boom, so the boom op can hold the boom and mix at the same time. *Haven't used it myself, but seems like a good idea.

 

[Stokestack]

In my opinion, 2 channels of really good analog inputs (with good soft limiters) is likely the best approach.

That would be nice. GOOD preamps or a digital input is pretty important.

The nice thing about a digital input is that it would allow us to overcome any on-board shortcomings with an external A/D converter. I'd think that'd make it easier for the Red team to future-proof the camera; they could solve the problem of getting audio data in, and then worry about tweaking an analog section.

 

[Hrvoje Simic]

It would be really nice if the 4 peak levels were visually placed around the screen in the scheme they record the sound. Simply changing the color of the monitored channel's peak level would in my opinion be the most logical option for multy sound monitoring.

 

[Steve Freebairn]

I understand that there are issues recording audio while over and undercranking, I just want to know if the option is available?

 

[Michael Mann]

GOOD preamps or a digital input is pretty important.

Reference quality should be Sound Devices preamps.

 

[GlennChan]

IMO, digital inputs aren't necessary. If you need that quality (which is most real situations you won't), you're better off recording double system and hopefully Redcine implements an automated syncing solution *that works*. If you shoot film and transfer it, the available solutions don't entirely work perfectly and the telecine operator (+assistant) always have to manually check sync and fix problems.

But if Red could get an automated solution working well, then it allows very high quality audio without much workflow hassles. Perhaps matching timecodes between Red and .bwfs would allow this. Recording audio separately is ultimately the highest quality approach.

 

[Hrvoje Simic]

Err....has anyone seen a good quality preamps which could fit into RED, especially for 4 channels ?

I wonder how much space for audio have the guys left in there.

 

[Nick Shaw]

I understand that there are issues recording audio while over and undercranking, I just want to know if the option is available?

As I understand it, the 'issues' are simply to do with how you sync the sound in post. Graeme said previously that sound will be recorded while overcranking. You then just need to decide what to do with sound recorded while shooting at 120fps when the picture is played back at 24fps.

Nick

 

[Trevor Meier]

Since the RED's built around timecode, Redcine syncing to BWF in double-system should be relatively easy and workable... would save a hell of a lot of time for the online with RPL.

RE: remote control options, just trying to think outside the box... making RED the 'whole widget' isn't necessarily the right idea, but playing with different low-person-count workflows is where I live all the time.

 

[Nick Shaw]

Since the RED's built around timecode, Redcine syncing to BWF in double-system should be relatively easy and workable... would save a hell of a lot of time for the online with RPL.

It probably still involves a little bit of manual input to get the sync right at non standard frame rates though. As far as I know, timecode can be one of 24, 25, 30, 50 & 60 fps. RED can shoot at fully variable frame rates, but other external sound recorders are unlikely to allow non-standard time-code rates.

RED will allow shooting at eg 120fps, with a 'project setting' of 24 fps, so I assume 24fps time-code is what will be recorded in the picture meta-data. But what about sound? And what if that sound is recorded on an external device running 24fps time-code. The time-codes will not match.

Of course these issues have been around for years with film, and overcranked shots are usually done MOS. But digital overcranking presents the opportunity to improve the situation.

Nick

 

[Stokestack]

IMO, digital inputs aren't necessary. If you need that quality (which is most real situations you won't), you're better off recording double system and hopefully Redcine implements an automated syncing solution *that works*.

I can see the reasoning there. But given that the Red is going to ingest audio at all, it's going to involve recording a digital bitstream. What's the harm in allowing the user to pipe that bitstream in directly, bypassing the analog section? I don't know the engineering involved, but it doesn't seem like the additional work would be that great, especially if the bitstream is restricted to one of the sampling rates and bit depths that the Red records natively. And if you can eliminate (or render redundant) an outboard solution that has to be synced later, why not do it?

Plus, good stand-alone field recorders are costly (in terms of some of our budgets), whereas an outboard A/D converter and phantom-power pack are less so. I have a little belt-clip A/D converter and matching mic-power unit; I'd like to be able run the A/D's S/PDIF output right into the camera.

You could argue that this will be of minimal extra value once you convert your footage into a QuickTime or AVI file for editing, since you'll almost certainly want to break the audio out into separate files for sweetening in your audio app anyway. But at least they'll start out synced.

 

[David Fairbanks]

Why would you use an outboard A/D when the camera has one in it? It just seams like extras stuff to carry and get tangled.

I can definitely understand digital in, but that's only if it coming from a sound guys high quality digital mixer that has better pre-amps and A/Ds.

 

[Brian Broz]

FWIW I believe Sound Devices uses Lundahl pre-amps. Regarded to be clean, warm and Swedish

Brian Broz

 

[jbeale]

I can see the reasoning there. But given that the Red is going to ingest audio at all, it's going to involve recording a digital bitstream.

Depending on their design, adding external digital input could be just a bit of code in a FPGA, or it could require resources that aren't on the circuit board.

1) Reclocking data: an external audio bitstream will come in based on a different clock than the camera, hence you must have a re-clocking circuit. It might be 48 kHz but it will never be *exactly* the same 48 kHz rate as derived from the camera master clock. Reclocking is not rocket science, but it does take some digital hardware, which may or may not be currently available on the board.

2) Analog feedback: if you want to monitor that bitsteam via the on-camera headphone outputs, you would have to route the incoming data through a D/A to regenerate it as analog. Not sure if Red was doing that already, or was just taking the audio inputs as pure analog signals (pre-A/D), which has the advantage of reducing some audio delay and maybe circuit complexity.

 

[ericyoung]

As I understand it, the 'issues' are simply to do with how you sync the sound in post. Graeme said previously that sound will be recorded while overcranking. You then just need to decide what to do with sound recorded while shooting at 120fps when the picture is played back at 24fps.

Nick

Surely if you're shooting 120fps, you aren't going to be using sound recorded at 120fps and played back at 24fps (if that's your projection rate)? Probably anytime you shoot "off-speed" you are going to be post-processing sound in some way, rather than using "sync" sound. "Fast" or "Slo-mo" is a visual effect, and rarely if ever will the sound be recorded and used at the same frame rate as the picture. At least I can't think of any examples!

Or maybe I'm being dense - it's late!