DV Info Net

DV Info Net (https://www.dvinfo.net/forum/)
-   Sony VX2100 / PD170 / PDX10 Companion (https://www.dvinfo.net/forum/sony-vx2100-pd170-pdx10-companion/)
-   -   Multi Camera timecode sync (https://www.dvinfo.net/forum/sony-vx2100-pd170-pdx10-companion/28735-multi-camera-timecode-sync.html)

Michael Tan July 10th, 2004 10:48 AM

Multi Camera timecode sync

There are a couple of events coming up, and i was thinking of doing a multi-cam recording setup. To help things along while editing, i thought it would be good to have synchronized timecodes in the 2 cameras that i will be using. Would someone verify if the following is somewhat correct:

2 cams set on DVCam recording more, TC MAKE on PRESET, TC RUN on FREE RUN, TC PRESET RESET button pressed on both cams simultaneously, 3rd cam on DV LP (cheapo cam :) for cut away shots, placed at a "safe" location on full wide and largely unattended. Start DVCam 1 about 5 minutes before DVCam 2, so that tape changes will not be at the same time for the 2 DVCams.

Did i miss out anything? I am concerned about not being able to catch any footage during tape changes.

What is the likelihood of clock drift between the 2 cameras? Should i be worried about the audio recorded at different camera locations being staggered due to distance between the speakers and the camera mic.s? Is there a better way to do this? For a dance performance, would it be a good idea to tap audio from the house mixer, or get sound direct from on-camera mic? I was thinking of recording both, each on 1 channel, but without backup (channel 1 AGC, channel 2 manual, low gain) for extra high levels, this leaves me slightly worried.

Any advice?

Boyd Ostroff July 10th, 2004 11:41 AM

Re: Multi Camera timecode sync
<<<-- Originally posted by Michael Tan : I was thinking of recording both, each on 1 channel, but without backup (channel 1 AGC, channel 2 manual, low gain) for extra high levels -->>>

This is essentially what I do for our archive videos, although I use only one camera. Audio sync may be a problem however. For a rough ballpark, figure that sound travels 1 foot per milliseconds. Therefore, if the camera is 33 feet from the stage (where the mikes are) 33 / 1000 = 33 ms = 1/30 sec = 1 video frame. Since I shoot ~100 feet from the stage, when I edit I move the track with the on-camera mike 3 frames earlier than the track from the sound board and this seems to sync nicely. If I don't do this then there is a very disconcerting echo. But I'm recording opera, not dance.... it might be less noticeable in your case.

Regarding syncing multiple cameras, that sounds tricky and I don't have any experience there. However, what I do is to shoot one performance with wide shots, then a second with closeups. Afterwards I edit them together. In the wide shots you can't usually tell whether the sound is slightly out of sync, so this seems to work pretty well. I use the audio from the night that I shoot the closeups.

Mike Rehmus July 10th, 2004 02:26 PM

There is no need to worry about TC sync. Since you cannot jam prosumer cameras with TC, they won't match up no matter what you do.

But the cameras are very consistent, camera-to-camera, speed-wise. Even between pro, prosumer and consumer cameras (I use all-Sony). Make certain that all the cameras are turned on and never turned off except for tape changes. That way you don't have to constantly resync.

I regularly sync 4 cameras on the timeline (I use Edius from Canopus). What I do is make each track a PIP and then move them to the 4 corners of the screen so they are 1/4th the screen area. Then I pan the sound from the main camera to the left and the sound from the next camera to the right. Makes it easy to get sound sync because it is so easy to hear the relationship. Then if the image of the second camera is slightly off, I can move it a couple of frames to match to the main camera. I then repeat this for the other 2 cameras.

When the images are all in sync, I then mute the sound for all but the main camera (which recorded the sound from the source). I'd only use sound from one of the other cameras in case the main camera had a sound problem.

Now I can scrub the timeline and select which view I want. I move that view to the main camera timeline, erasing the other timelines for the duration of that clip. I just continue until done.

The most recent High School graduation took less than one day to fully edit using this method. I had 4 cameras running for that one. 1 DSR-300, 2 X PD150 and 1 VX-1000. The VX-1000 is set to record the entire field from the top of the grandstand and gives me a go-to camera should the other cameras have problems or the operators be switching tape. A consumer camera could do this quite well if you didn't have the odd spare camera for the task. I do use this camera to capture 'room tone' that I add to the main sound track to improve the ambience.

With my editing system, if the visual record isn't in sync with the sound, I can slide the sound with respect to the video to make it so. But I normally use my DSR-300 with its 3 hour tape load as the main camera and record the sound system/microphones/wireless to it so I have no sync problems.

Law Tyler July 10th, 2004 06:47 PM

Huh? Huh? Huh?

I constantly shoot 2- and 3-cameras. W/o any formal videography education and no videographer friends (or strangers) around other than good guys here like Mike, I figured out to use the photographer flash to sync the video. Can't stop the recording like he said.

For audio I just use it from one camera after cutting too.

Wayne Orr July 10th, 2004 07:08 PM

You got some good advice from Mike, Mike (wha?), but I suggest you experiment with continuous timecode. As Mike said, you won't be able to get both cameras "frame accurate," but with a little practice, you can come close. Set up the two cameras as you suggested, and get a house audio feed for both of them if possible. (If you only have the feed to one camera, you will temporarily lose the good house feed on the tape change) Mike's idea of using the DSR 300 with its 3hour record is the way to go to eliminate this problem. Anyway, just before the beginning of the show, roll all cameras, and fire off a strobe flash unit to give you a visible sync mark.

In post, line up the cameras to the flash. Note the difference in timecode between the two cameras. You should have a difference of only a few frames, if you poked your "set" buttons at the same time. This difference of a few frames will remain constant throughout the show, including the tape changes, which will be a big help. It will even help if someone accidentally stops recording temporarily, which happens with inexperienced operators.

Be sure to get a feed from the house. With everything else going on, it's very tough to get a good recording from speakers in the heat of battle. I suggest if you do one channel with the on-camera mic, you leave it in AGC. But a feed from the board should be in manual, and set before the beginning of the show with help from the audio mixer. If he sends you a zero tone, set you camera to about -20db, and leave it alone.

Good luck
Wayne Orr, SOC

Michael Tan July 12th, 2004 08:03 AM

Thanks everyone for the very informative responses - learnt much from this, and that's what i like about this group; being able to learn so much by simply lurking around.

My biggest concern now is how to deal with tape changes. Because I do not have full size DV tapes, I have to deal with a maximum 60 minute record time on the PD170s, and i may not have a chance to pop a flashbulb before the event begins, unless i do so even before the theater is full, which seems like a waste of tape to me (inevitable, i suppose).

If the event is going to last for more than 60 minutes, and the cameras were started at the same time, i will lose footage from all cameras (maybe except for the consumer cam set on full wide). If one was started early, then sync may be a problem...

I supppose i going to have to lay all 2-3 camera tracks one atop another and check sync via the method suggested by Mike. I must admit that it never occured to me before to try the p-i-p and panning the audio trick before. Great tip!


Eric Stemen July 18th, 2004 12:03 PM

If you wanted, although i don't think anyone has done this, you could buy some infrared led's then tear apart an old remote control car. Put the infrared led's into a cluster where your camcorders are focused on them, then make the led's light up for a second from the torn apart remote control car. No one else would see the led's light up because we can't see infrared, but your'e camcorders could probably see them. Just a thought.

Mike Rehmus July 18th, 2004 05:08 PM

Designate one camera as the long-player and put 80 minute tapes in it. That will give you coverage. Also you can stagger the start times by a bit. One or two minutes will give someone who is prepared, enough time to swap tapes.

The IR led is an idea. If you have an area that all the camera can see, put an IR repeater in that area and then trigger it with a remote control.

All times are GMT -6. The time now is 01:22 PM.

DV Info Net -- Real Names, Real People, Real Info!
1998-2021 The Digital Video Information Network