How about good quality Audio?
 

I know the quality of a D-SLR movie function is pretty good. Especially with a high quality 35mm lens with a large aperature. But, image quality is only 40% of the overall impact to the audience. The other 60% is high quality audio - that calls for XLR connector class microphones. I doubt the D-SLR camera will be able to provide that for a long time to come.

Actually you can have it right now, with the BeachTek DXA-4, DXA-6vu or DXA-6HD.

And that's just three options... there are a variety of ways to get XLR audio into a D-SLR.

Or go double-system like the filmmakers do, and record audio separately.

Chris,

Having the connecting box is one story, but, can the D-SLR records 48khz at 16 bits PCM? I doubt they come with an AD with that quality.

(In fact, I just checked on the Nikon D90 - it only records mono).

So - if I need serious audio, I have to bring my Sound Devices 722 recorder along - that means, another problem - how to have accurate sync between the two?

The Canon 5D Mk.II does indeed record linear uncompressed PCM stereo audio.

The most common way to sync double-system sound is to use a clapperboard.

Right, but it's 44kHz, not 48 (I *think*), and it's my assumption that there's no way to defeat the AGC. So even if you plugin the 5d-specific Beachtek DXA-5D, the camera will still be auto-adjusting levels. We need someone with a 5dMkII and a Beachtek to confirm this, though.

If 24p, manual shutter, and manual exposure are made possible on the 5dMkII, double-system sound will be a worthwhile compromise, given the price of other HD video cameras with full-frame sensors.

If you want pro audio to use with 5dmii footage, you've got one choice: double-system.

IMHO, the 44.1 vs. 48 thing is a non-issue, but the non-defeatable auto gain control (and complete lack of any manual gain control to my knowledge) and lack of any ability for monitoring are absolute deal killers on the audio front for anyone who is even remotely serious about their audio.

Is it not a little hypocritical to demand quality sound but not want to spend money on getting a tascam p2? You don't even technically need to use a slate, you could record a wild track through the camera and your professional sound through the p2. I have an xl-h1 with professional xlr jacks and I still use the p2 when I want to get really good quality sound. I don't think anyone is proposing that this still camera is the end all be all of camera's (scarlett and epic won't either, well maybe epic) it's a new tool and a cheaper version of a 35mm adapter, thats all.

Sorry I've not had time to do proper audio tests yet but I will soon. I plan on using a combination of a variety of mics, a Sound Devices MixPre field mixer and my Edirol R-09 to give me the best of both worlds. I have a Beachtek too but it provides no monitoring so I'm not confident about using it.

Results soon.

Dan

Am I understanding correctly that there is no way to set audio levels within the 5DMII? It's always on Auto Levels?
So even sending it a clean signal from a Beachtek (they're coming out with one in December the metering and a monitor jack I hear) would still be subject to auto gain, right?

In regards to monitoring audio, I've heard people used the composite out along with some adapters from radio shack to get a mini jack for their cheap canon camcorders. A quick search on google and I found this adapter which might work:

*OOPs. wrong cable. will post when I find another one*

*woot woot! Found this adapter. I've seen other ones before that were cables*
http://www.audiogear.com/cgi-bin/sho...&preadd=action

Admittedly, it'd be a bit of a hassle having to use so many cables. It'd be great if someone can make adapter that goes from AV straight to headphone.

I will mostly likely hook up my AT1800 and monitor it using the headphone jack there. I know I'm not hearing exactly what the camera is getting but it'd probably be close enough.

Monitoring anything but what the camera is recording is not really monitoring.

Go double system. Use a good quality camera for the video and a good quality digital recorder for the sound. Invest a few bucks in a simple slate, or make one.

I've never had any synch problems with my MicroTrack, plus it's nice not having to tie the camera to the sound guy with a long cable. Hollywood got along just fine for decades using reel-to-reel Nagras with 1/4" tape. If you're really concerned about losing sync, do a tail slate at the end of the shot along with the slate at the beginning, and see how well it lines up with the video.

People act like it's such a hard thing to sync up a separate audio track with video. Slated properly, you have a wonderful single spike on the audio track waveform when the clapsticks close, which you line up with the video frame showing when the sticks close together. Takes maybe five seconds. Once aligned, group the audio clip with the video clip in the timeline, and they can be moved, edited, and shifted as a single item.

Martin

You don't even need clapsticks if the sound is run to the camera as well, like I do with my XH-A1. However, I find that even with a clapperboard it does take longer than 5 seconds due to file management, such as splitting up the audio file into small chunks that match the video clips (for fast audio editing).

While MOS works for some of my shoots, there are all sorts of genres that will not be helped by the double system sound workflow. Some event shoots will have over a thousand different clips in just 5 hours. That would take a long time to sync sound.

There should be some software to auto-detect the point where waveforms line up and sync sound automatically, especially one that worked despite auto-gain.

Double system might not work for everyone, particularly video journalist that are doing a lot of run and gun. For film work or any controlled environment, i agree separate audio is the better way to go.

A video journalist needs only to add a Sennheiser MKE400, per my photos at:

http://www.dvinfo.net/conf/photo-hd-...amera-box.html

Primary drawback isn't the lack of manual levels control so much as the inability to monitor audio while recording. The AV output jack could have easily been re-purposed for headphones (as it is on Canon camcorders) but that function has obviously been overlooked, unfortunately.

Sample video (NYC subway performers):
http://www.palsomedia.com/canon5d2/n...ground_5d2.wmv
(download and save)

The first part part is with the built-in mic.
The rest are with the MKE 400.

It's very UNlikely these cameras have AGC. There will be no pumping. This is a worry that has been an audio myth for several decades.

The cameras most likely have a limiter that prevents clipping. Which means no signal can exceed 0dB. But, most likely peaks are kept below -12dB. This is exactly what you MUST do with digital -- except a limiter can do it faster than you can.

With digital audio that's all one needs as long as you use an external mic that is matched. Matching is something you do BEFORE you going out shooting. If you know your mic will not drive the recording into distortion, you are set.

YOU are where the audio IS. If you can hear it at the camera, you will be recording it. If you can't hear it -- forget about it.

If you want to hear audio QUALITY -- do the XLR boxes will have an earphone jack? If not, if the audio is output via the AV jack during recording -- you can use that signal with a tiny amp. (One IC and a battery.)

There is no Confidence playback for video. If you think audio might not make it from the audio jack or internal mic to the record heads -- then you should be equally worried about video. Yet today, no one worries about this. Plus, you certainly want to make a test recording.

PS: If you notice -- most of the posted movies don't use on-location audio. Or, very little. For ENG, the audio should be more than adequate.

You can have a bad connection between your mixer and the mic input jack. I think that's what might worry most people, especially since it is an 1/8" connector - not exactly robust. In addition to cable failure, you might forget to connect it or it might inadvertently pull out. If there were visual audio level indicators on the lcd screen of the camera I would feel more comfortable not being able to monitor directly off the camera. Are there visual audio level indicators?

Huh? A true limiter is only preventing clipping at the very top of the scale. How's the gain set then? How does the camera "keep levels below -12?" Because somewhere, somehow it sets the gain -- the point being, you don't set gain, it does. Now sure, maybe it won't obviously pump, but surely in a loud environment it lowers the gain (doesn't seem like it could just fully depend on a limiter without sounding like crap in an extremely loud environment) and in a quiet environment it raises the gain? Without manual gain control, something is setting levels, and I find it hard to imagine there's a constant pre-set gain with all overs handled by a limiter. But hey, what do I know?

The engineers set a gain value. They set it based on the sensitivity of the internal mic.

That's why mics have a sensitivity spec. like -60dbu. And, why pro camcorders have a sensitivity spec. And, why pro camcorders have settings like -50dbu, -60dbu, and -70dbu. You set your camera to be equal to or higher (smaller negative value) than the mic rating.

The same can be done with any of the converter boxes. except YOU need to set the box output level yourself.

the reason you need to match is because you don't want your input to exceed the analog stage input rating because if you do so it will create analog distortion that can't be eliminated. Yet, you want the signal high enough to get the average level to be mid-scale.

the 16-bit range takes care of everything else -- although these cameras may have only 12-bit a/d's because IMHO they were designed for ENG. A reporter talking to someone. but, as the subway sample shows, on-location music sounds fine for ENG. (a bit bass-shy but that is likely the mics.)

PS: the real problem is the way too much notion blur. For 24p, the shutter should be 1/50th or 1/60th.

look at this clip:

Canon 5DmkII with Nikon 85mm lens at f1.4 in broad daylight on Vimeo

you can just barely hear the hammer on the bricks, I assume it was a good distance from the camera. There is however a ton of hiss, which to me indicates an AGC system cranking the gain as high as it can go in the absence of any noise. Whether it pumps aggressively or not is something we won't know until someone can specifically test it, but it does appear to have AGC and not just a fixed gain+limiter.

Evan,

Erm, the reason the sound was so bad on my clip was that the MKE400D on the top had run out of battery without me noticing. Obviously if I had been able to monitor it then I would have known! So yes the AGC then kicked in and generated the background hiss.

Its for this very reason that I'm keen on monitoring and a backup audio device in case of emergency.

Dan

If someone is feeling like gambling on a solution you could look here http://www.dvinfo.net/conf/private-c...c-pre-amp.html

The Sound Devices mic pre amp looks perfect for 5dmkII use, only single channel though.

Dan

Certainly it's possible the camcorder "created" the hiss, but it's equally possible the hiss was generated within the mic because the battery was failing.

The simple test is go in a closet and record. If a camera has dumb AGC it will raise the gain to its max. You'll hear hiss.

However, a smart AGC will not do this. So you need a second test. In a room with a low level of noise, turn-on your MKE400. A smart AGC will not raise gain on the mic when it is turned-off. Once turned-on, when it senses "some" signal it will raise the gain.

Now the question is how much does the gain change and how fast? Ideally it should adapt itself to the average input and change very slowly. This should be acceptable for journalism.

Trying to turn these cameras into "movie cameras" is inviting frustration.

As far as I'm concerned, that's the DEFINITION of AGC: the camera is changing gain.

So, to be honest, I'm confused about the whole popular myth thing. In my experience, which I admit might be much less than yours, I haven't yet met a consumer camcorder (that couldn't be set into manual levels) that didn't ride the gain in some form or another. I find it hard to believe that the 5d has a set gain plus limiter. I simply don't believe it.

Feel free to prove me wrong though...

That's the problem with "definitions." Technically a 911 has an Automatic Transmission and so does an F1 car. Yet, these AT's don't really behave very much like the AT in a Ford Pinto.

I've reviewed camcorders for 15 years and from the around the time DV was introduced while the spec sheets still claimed AGC, in fact, the behavior had none of the negatives of an AGC. (The reason, of course, is the switch to PCM audio recording.)

Analog-based AGCs had certain negative aspects. When digital electronics came along it became possible to have an AGC that behaved as would a human. When you "ride the gain" (for a digital recording) you follow a VERY simple set of rules based upon the incoming signal level. It is trivial to build these rules into a DSP chip. The difference is that the DSP is far faster and more reliable than you can ever be. Can it make an error? Yes. Can you make an error? Yes.

So the myth really is that all AGC's are the same. And, therefore, should all be avoided. The problem is in the word AUTOMATIC. AUTOMATIC in the digital world is very different in behavior than it was in the analog world.

PS: That doesn't mean the DSLRs have smart AGCs. It all depends what IC they buy for audio I/O. Or, what they designed into their I/O chip.

That depends. If I don't want the level changed, then it's completely un-reliable to me. Personally, as long as my levels are up in the decent resolution part of dbfs (s/n), I prefer to do my compression and other tweaks in post. But again, it depends on what you're doing of course.

But that's not what you said, and that's not what I implied either. You said no AGC, when clearly these cams ride the levels, which was my point.

I'm not saying they can't do it in an intelligent way, or that they can't do it without pumping, or that they have long release times, I was just saying that they ride the levels. For some, that might be a good thing, and for others it might not, but the fact there's no gain control whatsoever on the 5dm2 is pertinent fact -- not that I personally expected anything less, I was actually shocked there was even an input to begin with.

If you want to get super geeky record an hours worth of time signal and covert to mp3

Then feed the time signal from an iPod to your 5D2 and to your sound recorder.

Here's a short (6MB) clip which demonstrates the auto gain working (using the MKE 400):

http://www.palsomedia.com/canon5d2/a...o_gain_5d2.wmv
(download and save)

What you hear is a very good job of preventing audio clipping. When the overall signal gets near clipping, the gain is reduced which naturally lowers the background noise. It's hardly objectionable. Clipping, which would ruin your audio would be far worse.

Of course, a human might think far enough ahead to set the gain based on the loudest noise. If they knew ahead of time what that would be at a race track. And, where exactly on such a tiny camera would you put the knob? Or, do you want someone to stop and use a menu. I really doubt anyone shooting in gun & run mode at a race track would have time to do this.

Most operators shooting with a $2500 camera would be very happy to get the shot for the nightly news or a webcast.

If and when Canon decides that a video from a DSLR can be used for purposes other than the web or quick gun & run video grabs, there are more than enough buttons on the camera for manual control.

The top dial is already being used to adjust the speaker volume during video playback so it makes sense to put the gain there. That dial is normally used for the shutter when shooting stills, but since you don't normally change the shutter during video recording, the shutter can be put in the menu. And you still have the rear dial for the aperture. The EF mount doesn't have servo-zoom so you don't need a button for that.

Not to beat a dead horse, but here is a paragrapg from a TI TSC2100/01 application note. These are the "rules" by which this AGC operates:

Without speech or signal, decrease the Maximum Gain Applicable variable to have an acceptable level of amplified noise.

Next, with the lowest speech or signal source, increase the Noise Threshold
variable to a level so that the weak signal can be detected and gained.

Then, increase the attack time if the speech initially sounds bad; decrease the decay time if the speech sounds too noisy for too long at the end.

"An AGC can automatically adjust the gain so that the signal is maintained at a certain nominal constant level (called target gain) over a changing range of real-world
conditions."

This simple IC has many parameters:

1. Target gain = –5.5 dB
2. Attack time = 8 ms and decay time = 500 ms
3. Noise threshold = –90 dB
4. Maximum gain applicable= 59.5 dB
5. Hysteresis = 2 dB
6. Debounce time from normal to silence = 0 ms
7. Debounce time from silence to normal = 0 ms

Please note I'm not claiming any of these still cameras use this type of chip.

Double-system logistics
 

Could anyone with experience using a 'double-system' for audio and video offer some pointers? Specifically, I'm wondering what the best way to carry a digital flash recorder with internal mics in an X-Y pattern (Sony PCM-D1) at the same time that I'm shooting with the 5D Mark ii alone. Do I just have to find a friend?

Preventing the audio clipping is fine, it's the slow creep up of ambient noise afterwards that's objectionable... you can argue all day about whether it's really 'AGC' or not by a variety of definitions but in the end I don't want ambient noise creeping up like that and then clamping down as soon as someone talks or there's a loud noise - it's the audio equivalent of autoexposure clamping down when someone walks into frame with a white shirt. It sounds unnatural, it sounds bad, and it sounds unprofessional....

You don't need to know exactly the loudest noise ahead of time... you pick a comfortable level for what matters to you and set one channel -10db to that level. If you get a sudden unexpected spike in noise you can recover it from the lower channel. Or you can add a limiter which only clamps on peaks that would clip and otherwise leaves it at the level you set it.

If you could set it.

At least they gave us exposure lock.

Is there a device that can record audio and simply write a time code to the 5DII audio track. The audio wouldn't be used from the 5DII, just the time code.
Someone half jokingly talked about recording the broadcast time signal to both. But we would want something that would sync automatically in a non-linear edit program.
A poor many gen lock. We don't need extreme accuracy.

You probably want to get it away from the camera. These mikes often hear what's directly behind too. Experiment.
Start the audio and video and then clap you hand in a location visible to the camera. This will allow you to easily sink audio and video. If your doing a lot of takes you can buy a clapboard.
I suggest leaving the audio on in the camera too as a backup and reference for syncing.

For music I use the Apogee Duet to a Macbook Pro (Mac only):

Apogee Electronics: Products: Duet

This has an A/D converter close in quality to their recording studio products.

auto gain relief
 

I wonder if you could feed the audio input with some kind of jam or reference signal, an ultrasonic one that only dogs can hear, at a constant or adjustable level, which would then set the auto gain accordingly. Then you could filter out the jam signal in post, and have your human audio where you want it.

Can anyone share their wisdom
 

Can anyone share their wisdom on using a separate recorder / a slate and syncing in post? In the future I’ll be doing A LOT of interviews and maybe there’s a tidbit of priceless info that’ll save me time and headaches:)

Plenty of info in the audio forum. The 5D specific suggestion I would make is to consider recording audio to both camera and external, if convent. Also, in an interview situation the 5D audio might work fine alone if the 12 minute record time is acceptable (with an off camera mic).