Is it possible to record audio straight into camera yet?

[George Hupka]

Okay, I got a Redmag reader in late yesterday, so finally I'm able to do a bit of experimenting.

Started by reinstalling all firmware to the current beta build, which is required for Pro I/O operation.

First test was from a 442 line level to the Pro I/O - inputs set for Line In, 0VU. The return via XLR-5 is still very hissy. However, the playback from the card is fine.

Second test, I switched the 442 output to mic level and set the Pro I/O inputs to Balanced. Exact same results - hissy monitor but the recording is good.

Thought I'd go right to the torture test and pulled out the Sennheiser G3's (Sorry Marc!) On the monitor out, in addition to the hiss I had experienced with the the mixer, there was also the "pulsing gain" effect that I'd run into before. However, this time the recording seems to be clean - noise is what I would expect to hear from the G3's.

So, I would have to say at this point it looks like the Pro I/O is good for recording, but the noisy return makes it impossible for a sound person to know for sure whether the camera is recording a clean signal. That would be a pretty big drawback for anyone hoping to go single-system without a safety net.... But if you always do a backup recording from the mixer, now at least things seem to be a lot more stable.

If you are hoping to "run and gun" without a sound person... personally I wouldn't do it without a rock-solid headphone monitor, which now seems to be the biggest issue. The hiss that's coming back from mine would make it very difficult for me to hear actual audio problems in the field - sound person can monitor the mixer, but if I'm shooting I can't! (And as there are no tools designed into the Epic to adjust audio in a "run and gun" situation, I would suggest that you are using the wrong camera for the job....)

My next tests will be back through the "brain" inputs to see if those are any better (firmware improvements?) or if it's just the Pro I/O.

 

[Mike P.]

I'm sorry, but what do you mean by "the return" (via XLR-5)? Where are you monitoring the hissing from? The camera headphone jack or the mixer via an audio return FROM the camera (after it's been feed from the same mixer to the camera)?

If I were running and gunning, I'd be using headphones connected directly to the camera (under the impression that it is pumping out the audio being recorded by the camera via Pro I/O or front jacks.) Monitoring anything other than that seems somewhat counterintuitive to me... The sound guy wouldn't be monitoring a return feed from the camera, as that's not what he's recording to his isos.

 

[Christopher Mills]

Mike, the audio return IS what sound people prefer to monitor. we try to bypass the headphone amp in all camera situations where this is possible.
the theory is that the return is part of the signal path from input socket to media, while the headphone amp is not.
As I have not had a hands on with the pro IO, I do not know if this signal path paradigm is correct here. In all other pro cameras, it is..

 

[Mike P.]

Mike, the audio return IS what sound people prefer to monitor. we try to bypass the headphone amp in all camera situations where this is possible.
the theory is that the return is part of the signal path from input socket to media, while the headphone amp is not.
As I have not had a hands on with the pro IO, I do not know if this signal path paradigm is correct here. In all other pro cameras, it is..

Touche... That's why I'm not a sound person. Still seems weird to me, though. Wouldn't it make more sense to listen in to what the recorder/camera is recording (via headphones) rather than what you think it did record or will be recording (via a return)? This is a perfect example of hiss being added after the signal has been recorded (since it isn't exhibited in the source audio files.) I understand wanting to avoid headphone amps in order to get the truest audio signal, but it's also adding an additional step/travel which is introducing artifacts (potentially more so than the headphone amp.)

George, is the camera's headphone amp outputting a similar hiss or pulsing?

 

[Christopher Mills]

The audio return in other tape cameras was "post heads", the headphone was not.. the headphone amps in Sony and Panasonic cameras are still "pre-record" and the camera audio lines out are "post record" on tapeless cameras..
And, the channel selection in the headphones in most cameras is available only to the camera operator, so the sound person can't do on the fly channel selections of the headphone feed to double check each channel individually from that feed...
A camera audio out will frequently assign the channels to their own filaments in the cable, allowing the mixer to more truly isolate the channels in their return feed.
That's how its supposed to work, but I am not certain it is that standardized anymore...
I don't know of any cameras that give you a faithful sense of audio through their headphone amps... many of them will either make you panic needlessly, or worse... fail to reveal low frequency or high frequency sounds that ruin the recording for commercial use

 

[George Hupka]

OK, All of my tests yesterday were through the XLR-5 return, which as Christopher has said is what my sound guys usually use on Sony/Panasonic cameras. I've got a couple of umbilicals lying around that have breakouts with 1/8" monitor jacks but not handy - they're getting used a lot with EX's and F3's....

The issue for me with the Epic headphone jack is that even turned up all the way it is not loud enough for me to properly monitor - if there is any noise at all in the environment it overpowers what I'm hearing in the headphones (Epic is not alone in this, I find the same thing with most of the "compact" HD cameras as well... once you get to F800s/900s and other full size EFP cameras then you have decent headphone volume...)

So, the headphone monitor seems to be better, but I can't really be sure because it's entirely possible the hiss is just not loud enough for me to hear... I'll have to try again when I have an 1/8" breakout handy.

 

[Marc Wielage]

I don't know of any cameras that give you a faithful sense of audio through their headphone amps... many of them will either make you panic needlessly, or worse... fail to reveal low frequency or high frequency sounds that ruin the recording for commercial use

This is sadly true.

The issue for me with the Epic headphone jack is that even turned up all the way it is not loud enough for me to properly monitor - if there is any noise at all in the environment it overpowers what I'm hearing in the headphones.

Ditto. I would caution you that long-term monitoring at high volume levels is bad for your hearing. One known issue about dialogue recording is that we try to use the exact same headphone monitoring levels every day, to make sure the dialogue levels are at least consistent. But every environment is different, actors are different, scenes are different, microphones are different.

In addition to needing a good sound mixer on set, getting a good dialogue editor in post is a godsend. They can totally save the mix in some cases, find alternate lines, minimize noise, and rescue dialogue that would be otherwise lost. This is not work a traditional picture editor can do, and requires a whole different skillset.

 

[Antti Pirskanen]

The audio return in other tape cameras was "post heads", the headphone was not.. the headphone amps in Sony and Panasonic cameras are still "pre-record" and the camera audio lines out are "post record" on tapeless cameras..
And, the channel selection in the headphones in most cameras is available only to the camera operator, so the sound person can't do on the fly channel selections of the headphone feed to double check each channel individually from that feed...
A camera audio out will frequently assign the channels to their own filaments in the cable, allowing the mixer to more truly isolate the channels in their return feed.
That's how its supposed to work, but I am not certain it is that standardized anymore...
I don't know of any cameras that give you a faithful sense of audio through their headphone amps... many of them will either make you panic needlessly, or worse... fail to reveal low frequency or high frequency sounds that ruin the recording for commercial use

Indeed, on tape based cameras and on some audio recorders too (Nagra DII) there was a separate "confidence head" that read the track that had just moments earlier been recorded by the actual record head. If you wanted to monitor the "pre record" audio on these, you selected EE or Electronic-to-Electronic monitor mode.

Nowadays with solid state storage, a similar function to a confidence head is actually performed by the flash memory controller or processor. Parity bits and error detection code are used to verify that the bit stream is actually written correctly on the SSD or a memory card. In a sense, the memory is just a bit bucket that receives the bits that have already been converted from analog to digital at an earlier phase of the signal chain. A lot of dedicated audio recorders use twin or triple memory bays in order to provided redundancy for hardware based recording failures. Also, a special robust file format that doesn't need to be separately finalized when stopping the recording is sometimes used to protect against file corruption in case of sudden power failure. When a single system is being used to record both audio and video on a single file, there is obviously many single more points of failure compared to an audio only recorder. Because of bandwidth requirements there is often quite minimal redundancy in the actual memory storage unit. It is my understanding that enterprise level SSDs, which I am sure RED also utilizes, have a significantly more robust error detection and correction systems built in.

So, the analog signal that is being monitored on the headphones of a tapeless camera or a line out connector is essentially always "pre-record".

 

[Nikhil Kamkolkar]

Folks, I'm experimenting with this. I have a question on the witness marks in the audio meters we see in the lower right of the touch screen LCD. The manual (pg 12) talks about the color coded audio level meter range to be from -36dBu to +20dBu. But the meter shows clipping around 3/4th into it. Where exactly is +20dBu on this meter (lower right of the touch screen LCD). The meter has five marks - the 1st I'm assuming is 0dBu, the second +4dBu... etc. But does anyone know what the official take is?

 

[Brian Merlen]

I have to do audio today on the Scarlet for the first time, with a BMD multibridge pro, avid capture tool and the shittiest mixer money can buy...in conclusion FML lol...

 

[Marc Wielage]

I honestly don't know what the hash marks measure out to, in terms of sound level. (Again, I don't mean to criticize Red; Sony, Panasonic, JVC, Canon, and other companies also violate from known audio standards and have weird meter levels and odd ways of reacting to peaks.)

My typical philosophy is to set up the sound mixer and recorder with a -20dBfs tone, send that to camera, and let it go to about mid-point. I then record dialog, sending a peak-limited feed (with the mixer) to camera, with the dialog averaging to about -10dBfs. Usually, that avoids clipping in the camera. But again, my goal is to make this only a scratch track.

I'm surprised that the manual refers to sound levels in terms of analog levels (-36dBu to +20dBu), because this doesn't really relate to a digital world, and the camera records only digital sound. 0dBfs is the ceiling, and we need to peak about -5dBfs below that. In truth, the preamps in all these cameras don't have a lot of headroom, so it would make sense to be cautious and keep the levels conservative.

 

[Nikhil Kamkolkar]

Thanks Marc! The manual does refer to the 'equivalent' dBfs values also in parentheses. But I hope RED will add some additional info in the manual on how best to use the meter levels for setting up the gain stages to maximize the quality of audio recorded in camera.

Your notes are very helpful. I just got my MixPreD which I'm using with two Tram lavs/Sennheiser G2 wireless system to pipe audio into the camera for my test/smaller shoots. I'd have a audio person for anything more substantial, ofcourse. Thanks again!

 

[Robert Hart]

I can't speak for RED as I am one of that sinful luddite generation of SI2K users, more of whom may be quietly stalking around this forum. My solution is crude and simple. The SI2K is basically a Windows computer so I can set my internal mixer levels so that the camera sceeen audio bar display becomes co-incident with the levels display on the MixPre when it is itself set to industry standard. Calibration with tone would be better but I found I was not able to do this successfully.

As I record mostly single mic mono dialogue on the Mix-Pre I have been setting my camera left channel lower by about 10 db to give myself half a chance of recording recoverable audio if I am neglectful and allow it to become a bit hot at the mixer. I think they call that "bracketting the levels". I imagine you can also set internal levels in the RED/EPIC/SCALETT. The Mix-Pre has a trimmer so that audio-out from the camera can be matched so that by monitoring with headphones via "tape return", gives you a fair chance of getting it right when you are doing it all alone.

 

[Jude Byard]

Thanks for sharing. Not much as an audio guy.

 

[Joel Arvidsson]

Does anybody know how you "bracketting the levels" inside the camera? I cant figure that out. Have not gone throw the menus in a few updates thoe.

 

[Björn Benckert]

We use the pro I/O and microphone only now. No external recording device. Works like a charm. Nice to have it all synced up and ready to play instantly for the DIT and straight from camera. I just wish the camera had:

1. a built in microphone just like the once we have in our macbooks or such.
2. a built in speaker for playback. Does not need to be good quality.


Why?

It's quite nice to allways have a scratch track. I like to talk to the camera and say what lens was used, if if was a good take etc.
and it would be nice to get the playback with sound if wanted. To me it would be logic to have built in speakers (and maybe microphone) in the next generation of touch screens.
Then the mic would get away from the fans and the playback sound would come out close to the screen. And we would not need any extra cables etc.

 

[ericyoung]

Audio ( together with affordable/built in 1080p recording ) is the Red cameras' weakest side. Seriously wish there was more love for audio at Red :sad:

 

[Mark Phelan]

I like to talk to the camera and say what lens was used.

If you use the Canon mount, then all the lens information is recorded in the metadata. Very handy to be able to go back and see exactly what position the zoom was set on and at which f-stop. Seems so basic for all lenses to behave in such a manner. I'm spoiled by it.

 

[Marc Wielage]

Does anybody know how you "bracketting the levels" inside the camera? I cant figure that out. Have not gone throw the menus in a few updates thoe.

If you're relating this to "bracketing the exposure" for picture, then I'd say feed the same mono track to Ch. 1 and Ch. 2, set Ch. 1 normally (-20dBfs tone = -20 or halfway on the scale), and then drop Ch. 2 about -10dB. That way, if there's a very loud peak, you'll be protected from distortion.

But I still say you're better off recording sound separately and only using the camera as a scratch track.

 

[Rob Castiglione]

Sorry to raise the issue again but while we are talking about Epic and sound, is there any truth to the suggestion that later Epics have a different and quieter fan in them? I can't remember where I read this - I think on a sound board somewhere so there may very well be nothing in it.