AVCDH file with external audio recorder audio drift?

Hi all,

I'm considering buying a Canon Legria HF R606 and I would like to use it with a Zoom H4 external audio recorder.

When I import the Canon's AVCHD into FCPX, will I run the risk of audio drift when I sync up to the audio from the Zoom H4?

Thanks,

D

Typically you don't have a problem with drift, but this varies with the timebase accuracy of the devices. We have done hour-long shots with an HFG10 and G30 using a Zoom H4 and I don't recollect any drift problems.

However we generally use PluralEyes for sync which has drift correction. I don't know if FCP X has that; I tend to doubt it.

Even without drift correction and if shooting very long takes, you can usually cut the clip into smaller pieces and sync them separately without major problems.

A separate and controversial issue is whether using external audio recording is always needed. We usually do that but I sometimes see professional productions using in-camera audio. E.g, here's a frame grab of a recent CNN interview, possibly using two Sennheiser lavs (no shotgun) and in-camera audio recording. I can't be sure but it looks like the receiver outputs just run to the right-hand camera, apparently a C100 Mark I with a 70-200 f/2.8 lens: joema.smugmug.com/photos/i-tQ6Wj4s/0/X2/i-tQ6Wj4s-X2.jpg

I also don't see anyone monitoring audio, even in the wider shot: joema.smugmug.com/photos/i-k7RnTXj/0/X2/i-k7RnTXj-X2.jpg If so that would indeed be unusual. Maybe they have separate receivers off screen and someone monitoring and recording, but usually the sound tech (if present) is close to the shooters/producer to give feedback, use hand signals, etc.

That said there's an argument that for field interviews with ambient noise, the limiting audio issues are mics, placement, and post processing, not the camera pre-amp and ADC. While a professional crew will rarely make a mistake with an audio field recorder, it is possible, whereas in-camera audio is a little simpler.

Joema.

From what I've heard and understand, the audio components in a video camera are sort of an after thought. They usually won't produce sound that is as good as a seperate field recorder. Acceptable, yes, as good, probably not.

Double system is a pain, especially if you don't have access to an all in one mixer/recorder like some Sound Devices gear. But I think it is worth it. You still have the two channels you can use in a pinch if your something happens to the external recorder audio. FCP X is remarkable with it's ability to sync external audio to the camera recorded audio, even with out a slate! I still slate the shots though. Old habits die hard.

As you can tell, I like redundancies of EVERYTHING. Just in case Murphy and his law are in town. And yes this is controversial and will like draw more comments. Good luck.

JL

Jonathan Levin wrote: ...From what I've heard and understand, the audio components in a video camera are sort of an after thought. They usually won't produce sound that is as good as a seperate field recorder. Acceptable, yes, as good, probably not...

Yes, I often read that but I never see any controlled testing proving it. E.g, the HFG30 camcorder, 5D3 DSLR and Legria HF R606 the OP is considering all record audio using 16-bit linear PCM at 48k samples/sec, essentially CD quality. You could speculate the preamps somehow aren't as good; I frequently read that and accept it may be the case. However there are likewise many confident statements about human ability to consistently detect differences between audio amplifiers, yet in double-blind controlled tests this is unproven.

I'm not arguing to never using dual system sound -- we almost always do that. I just wanted to provide a counterpoint to the idea you *must* do that in every case. Various issues can cause poor audio, and these are often attributed to the in-camera signal chain, when the actual cause is external. E.g:

- Using poor built-in camera mics
- Using audio AGC
- Using incorrect audio levels

If using high-quality external mics, manual audio gain, and proper levels from the mic/receiver to camera, this is less an issue. Here's another viewpoint on this, admittedly arguing for external preamps: beachtek.com/is-it-possible-to-record-de...in-camera-on-a-dslr/

In my experience the main factors are microphone type, placement/usage, operator skill and ambient factors over which you have little control. E.g, in the CNN stills they are recording documentary-style footage in an outdoor location -- similar to what the OP posted on another thread his intent was. In such cases there will be all kinds of ambient noise. The noise floor will be higher, which would tend to swamp any theoretical difference in the audio signal chain.

The OP did not state mic type, just Zoom H4. While the onboard Zoom mic is better than a consumer camcorder's mic, that difference would be swamped by proper use of an external mic. E.g, a Sennheiser lav or Rode shotgun running to the camera will sound much better than a Zoom mic on the camera hotshoe.

Obviously both an external recorder and external mic are best but if budgets are tight and you can only afford one, the external mic is by far more important.

There is nothing wrong with recording audio directly to a camera. Most cameras will record audio as well as a Zoom, if you're using good mics. On-baord mics for most all creams suck, that's the thing to avoid. We use a JuliceLink and record all audio directly to our cameras and avoid the whole sync headache (BMD pocket, production 4K, Canon 7D). We get great quality sound.

Sync drift only happens when sample rates don't match, simple as that. Make sure your Zoom is recording 48kHz sample rate, and you'll be good.

And only use a separate audio recorder if your shooting situation demands it. Otherwise, run the mic to the camera.

So true! When doing quick interviews with up to four people we use a DR-70D and feed the sound to our DLSR and it sounds great. The key to the recording are the mics used and this saves a lot of time.

Yes, the microphone is the single most vital part of any audio work. Glad to see someone state it again. Thanks!

Hi BenB.

I would agree with you about the quality of the mic IF you were only talking about wireless systems. A Lectrosonics wireless set up is going to be much more reliable, and better sounding than say a cheap Azden wireless set up. And it should! It's like $3000-$4000 for a pair of those!

I spent hours listening to the lavalier tests from here: www.kenstone.net/fcp_homepage/lavs_brockett.html to try and figure out what to buy. It't mind blowing. They all had their good points!

However, I have heard some really cheap mics that sound perfectly good to my sort of sensitive ears. When i listen to the sound of a Schoeps ($$$$) wired shot gun and compare that to something like a Rode NTG3, it's different, but not necessarily better. Maybe a bit more noise floor. Sound to me is so subjective, I just go by what my ear tells me.

I think what turned my head is hearing the differences between different recorder/mixers. A Sound Devices mixer/recorder is so much cleaner (lower noise) than a Shure FP33 and Marantaz 660 recorder. So I think the mixer and recorder are really something to think about.

Jonathan

It's all in the A/D converters and any pre-amps used. Most cameras have perfectly good A/D converters. I've done sound work my whole life, and I can show you very clear differences between cheap mics and expensive ones. But, always get the right mic for the right job. Not all expensive mics are meant for live film recording.

And just to clarify, before I started doing the double system business, I was feeding audio from my mixer directly to a Nikon D800 and I was impressed with the audio quality. Apparently there was some issue with that camera and noise, but I haven't noticed that either.