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Old October 10th, 2003, 01:14 AM   #1
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Recording Audio For Video

Hello Everyone,

Next month, I am scheduled to video a highschool musical. This will be my first multicamera shoot. My major concern is not the video, but recording high quality audio. I will be using two Canon GL2s with MA-300 xlr adapters. I use Adobe Premiere 6.5 as my NLE. My original thought was to just run off the soundboard, through an attenuator (in order to bring the line level to a mic level appropriate for the MA-300), and into one of the cameras. On the other camera I would just record from microphones.

I am hesitant as to whether or not this will provide the results I am looking for. I am considering recording wild to another source, and synching back up in post. I have heard varying levels of success with this method. I have several audio recorders available including minidisc, dat, alesis hd24 w/ 96khz input, alesis adat w/ the BRC controller (see below), and a Nomad Jukebox 3 (ehh??).

One possibility I am trying to research, is to use the Alesis Adats along with the BRC controller. The BRC offers a video sync function using composite video input. I have never tried it, and am not even sure I understand how it works. Does anybody have any experience with this? The video sync input on the BRC is a BNC connector. The MA-300 has a BNC video out. Does this mean I could run out of the MA-300 BNC out and into the Video Sync on the BRC, recording 8 seperate audio tracks? If so would this be easy to sync, and keep synched, in post?

This is from the Alesis BRC Manual:

Video Sync In
"This BNC-type connector input can accept composite video as well as black burst video input. The BRC will automatically recognize the type of video signal (NTSC, PAL, SECAM) and its sample clock can be synchronized to the incoming video signal."

This seems awesome if it works the way I think it might... Would I be just as well off recording to mini disc or something like that and synching in premiere. Is it not as difficult to sync as some make it out to be. I just don't want dialogue over a 10-15 minute scene to drift out of sync.

The 8 digital tracks on the adat would be nice in order to mic the pit orchestra, run from the sound board, put out an audience mic for laughter and applause, and set up a few mics near the stage to mix later in my studio. Just worried about keeping everything in sync with the video...

any help will be appreciated.

Thanks,
Matt
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Old October 10th, 2003, 01:23 PM   #2
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Using the video sync input would keep the ADAT clock in sync with the camera that was supplying the video signal, but it wouldn't provide an actual match between the video and audio material like matching timecode does.
You'd still need to provide a sync clap to have a mark for aligning both media during editing, but you wouldn't have to worry about drift from that starting sync point as long as both devices ran continuously. If either stopped, you'd need a new sync mark or you'd have to experiment with nudging them until it looked right.
Since it's a long-form program with singing and music, I think it would be worthwhile to use the video sync, even if you ended up not using all 8 tracks.
If your HD24 doesn't have a direct video sync input, then any generic device that converts from video to word clock would serve the same function as the BRC does for the ADAT.
Even if you did none of this, since it's a two-camera shoot, you can easily nudge for sync and compensate for drift between audio and video. However, if you ended up using a combo of audio from two sources that aren't locked together you can definitely get drift problems within the length of a song since music tracks have to be matched with vastly greater precision than the relationship between audio and video.
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Old October 10th, 2003, 01:49 PM   #3
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Thankyou

Thanks for the input Jay. I will have to fire up the ADAT's and try a few tests to see if I can get that system working correctly. I'm pretty new with this stuff.
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Old October 10th, 2003, 02:47 PM   #4
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Good Luck and don't forget to at least record guide audio to both cameras no matter what else you do.
Your original plan of sending the attenuated output from the sound board to your cameras is good, i'd still do that even if you use an external audio recorder as primary sound.
Just remember to keep the sound board feed isolated on one channel of the camera and use your own separate mic at the front of the stage isolated on the second channel. A good-quality high-output mic like an AT3031 cardioid or a Rode NT-3 hypercardioid will do very well for filling in what the sound board lacks. If the sound operator or their sound equipment isnt functioning properly, this mic may end up being THE primary audio source.
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Old October 10th, 2003, 04:24 PM   #5
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One of the problems you may find with a feed from the board is that the sound is mixed so that it sounds good in the theatre. That is usually not good for the video. An auditorium sound system is designed for sound reinforcement, not recording. A big difference as I discovered.

I find that if I can get a feed of the vocals and pick up the music from a sweet spot in the auditorium that the mix will sound better. Usually.
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Old October 10th, 2003, 08:51 PM   #6
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Is there an option of using SMPTE timecode on a Canon GL2. I don't think there is, but figure it's worth asking. I've heard about recording SMPTE to one of the audio tracks or something like that. Would the GL2 need a special input for this though? If I could somehow get the GL2 running on SMPTE, the BRC for my ADATS has a SMPTE input that I could use to synch. I'm guessing in order to use this function of the BRC I need a higher end pro camera. Correct?

Matt
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Old October 10th, 2003, 09:47 PM   #7
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On the GL2 you'd have to record timecode onto an audio channel. Not all NLE's have the capability to read TC on an audio channel as opposed to the regular firewire TC.
I really don't think in this case that TC is worth the trouble and expense.
Protecting from drift with the video sync will be much more beneficial than achieving an absolute TC match between all your material. Since it's a long-form program, once you've established sync one time with all your media, that's all you have to do. That's fairly easy to accomplish by simply nudging your guide audio and your real audio into alignment on the timeline.
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