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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old February 13th, 2009, 04:16 PM   #1
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Cam out of SYNC?

at a recent wedding I used 3 cams, 2 XH-a1's and a HV30. One Xh-a1 does not sync with the other two cams. I synced the father kissing his daughter and a cameras flash so I know they are all synced exactly. By the time they get to the unity candle Cam2 (XH-A1) is off enough I have to cut out a piece so I can sync the vows with Cam1(another XH-A1)

I would have thought this to normal and something I have to live with except that the HV30 syncs perfect to Cam1.

Is this something I just need to live with, or is there a way to fix this, thanks.
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Old February 13th, 2009, 05:32 PM   #2
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Did you verify that both A1's and the HV30 were set to the same framerate? I've done that before, where I thought I selected 24f and accidently selected 30f for example. That would certainly cause the camera to go out of sync over time.
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Old February 13th, 2009, 05:46 PM   #3
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Originally Posted by Marcel D. Van Someren View Post
Did you verify that both A1's and the HV30 were set to the same framerate? I've done that before, where I thought I selected 24f and accidently selected 30f for example. That would certainly cause the camera to go out of sync over time.
Yes, they are all in 60i
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Old February 14th, 2009, 01:11 AM   #4
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Denny,
Camera flash sync is a great tool, but there are a few things to watch out for. First most cameras “preflash” before the main flash, and second, sometimes a flash is not visible at all in a given camera if it falls between frame exposures. It is possible for one camera to see the preflash and the other to capture the main flash. I just used camera flashes to sync a 4 cam shoot, and it took me 6 tries to get it set up correctly.

It is a good idea to confirm the sync by listening to both camera audio tracks together, or by checking another flash somewhere else in the timeline.
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Old February 14th, 2009, 05:07 AM   #5
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Forgive my ignorance of wedding and event videography technique here but why is it necessary that the cameras remain in sync for the length of an entire tape? I know you need to sync the cameras when editing a multicamera sequence but surely you don't treat the entire tape as a single clip and mimic live switching for the whole event, or do you? Wouldn't you slice and dice the original tapes into a number of much shorter scenes and takes first, and sync the shorter clips from the several cameras when it comes time to edit and add each few-minute long sequence to the timeline, rather than capturing the entire tape from each camera and dropping them into the timeline intact as the source for a single multicamera sequence? Or is my mind stuck on editing modes derived from film-style single-camera shooting where coverage is done with multiple takes and you're working in scenes and sequnces that only last a few minutes each?
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Old February 14th, 2009, 08:22 AM   #6
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Steve... I don't do weddings as a rule but do multi camera events quite often. I do, in fact, do "live" switching between sources. This is quite different than what I do for doco or nature pieces.

If using an NLE that can do multi-cam editing, it's much easier to lay entire tapes onto a timeline and "cut" to the best shot as the action unfolds over time. Once the multi cam timeline is edited, it can then be nested within another timeline with scenes that are not wanted edited out.

For example, I use three or four cameras for each race I shoot. Once I sync up each tape in the timeline, I expect it to stay in sync through to the end. If I need to remove footage, say during a caution period, I can cut the nested, multi cam timeline and be assured that the subsequent footage will stay in sync. It's easier to show than to describe.

I use this workflow because it's the easiest and most practical for capturing events.
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Old February 14th, 2009, 08:29 AM   #7
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Quote:
Originally Posted by Steve House View Post
Forgive my ignorance of wedding and event videography technique here but why is it necessary that the cameras remain in sync for the length of an entire tape? I know you need to sync the cameras when editing a multicamera sequence but surely you don't treat the entire tape as a single clip and mimic live switching for the whole event, or do you? Wouldn't you slice and dice the original tapes into a number of much shorter scenes and takes first, and sync the shorter clips from the several cameras when it comes time to edit and add each few-minute long sequence to the timeline, rather than capturing the entire tape from each camera and dropping them into the timeline intact as the source for a single multicamera sequence? Or is my mind stuck on editing modes derived from film-style single-camera shooting where coverage is done with multiple takes and you're working in scenes and sequnces that only last a few minutes each?
I use multiple angles for the ceremony (30-60 mins) if your getting a shot of the bride and groom from the front, and they are lauging to what the preacher said, it needs to be in sync, also when they go up to light the unity candle, that has to be in sync.

I am not talking a second out of sync, i am talking several seconds. For instance before fixing the wide shot showed them walking up lighting the unity candle then blowing out the individual candle before the Bcam even started them walking up.
Yes you can slice and dice but you also have to get the audio synced so it doesn't look like an old Chinese movie.
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Old February 14th, 2009, 08:38 AM   #8
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This is why I am asking I have been having this issue from the start. If all I need to do is send in a camera and get it fixed, would be worth it in the long run.
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Old February 14th, 2009, 10:26 AM   #9
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Is the second camera slowly drifting out of sync or does it happen at one place? I've had drop outs on one camera that made that camera out of sync, but it happens right where the drop out occurs and it is easy to see where it happens.
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Old February 14th, 2009, 11:08 AM   #10
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Originally Posted by Denny Kyser View Post
This is why I am asking I have been having this issue from the start. If all I need to do is send in a camera and get it fixed, would be worth it in the long run.
Denny,
It is likely not a camera problem which is adjustable. You can try and check with the manufacturer. Cameras which are not genlocked together run at their own frequencies which will drift apart over time. They are supposed to run at 59.97xxxx but the xxxx tends to be where the inaccuracy occurs. If one camera drifts compared to another it probably is a manufacturing or component matching issue but still within specifications. Most electronics have some spec with a + or - variation of 2% or even more so it is hard to guarantee precision. It is most likely luck that the HV30 syncs with one of the XHA1's. Chances are if it is adjustable then you would have to send in all the cameras so they can check the frequency of each one and try and match them. Maybe worth a phone call HTH
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Old February 14th, 2009, 11:15 AM   #11
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Originally Posted by Tripp Woelfel View Post
Steve... I don't do weddings as a rule but do multi camera events quite often. I do, in fact, do "live" switching between sources. This is quite different than what I do for doco or nature pieces.

If using an NLE that can do multi-cam editing, it's much easier to lay entire tapes onto a timeline and "cut" to the best shot as the action unfolds over time. Once the multi cam timeline is edited, it can then be nested within another timeline with scenes that are not wanted edited out.

For example, I use three or four cameras for each race I shoot. Once I sync up each tape in the timeline, I expect it to stay in sync through to the end. If I need to remove footage, say during a caution period, I can cut the nested, multi cam timeline and be assured that the subsequent footage will stay in sync. It's easier to show than to describe.

I use this workflow because it's the easiest and most practical for capturing events.
Thanks for the explanation. I would have though you would edit for time first, for example compressing, say, a 4 hour real-time event down to close to perhaps a 1 hour editied program length, and then at that point selecting the specific shots from the various POV cameras to go into an individual sequence and finding a particular common frame with each camera's take to establish sync, only worrying about staying in sync for the length of the sequence instead of the entire tape..
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Old February 14th, 2009, 11:26 AM   #12
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Denny,
It is likely not a camera problem which is adjustable. You can try and check with the manufacturer. Cameras which are not genlocked together run at their own frequencies which will drift apart over time. They are supposed to run at 59.97xxxx but the xxxx tends to be where the inaccuracy occurs. If one camera drifts compared to another it probably is a manufacturing or component matching issue but still within specifications. Most electronics have some spec with a + or - variation of 2% or even more so it is hard to guarantee precision. It is most likely luck that the HV30 syncs with one of the XHA1's. Chances are if it is adjustable then you would have to send in all the cameras so they can check the frequency of each one and try and match them. Maybe worth a phone call HTH
If this is the case I can live with it, and may actually be able to figure the drift %, then just adjust that clip to run say 1% faster or slower and be all set.
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Old February 14th, 2009, 01:22 PM   #13
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It sounds like your recording has several dropouts. Try this: Play back your suspect tape from beginning to end. Listen and watch carefully for unintentional cuts during your shoot. If you you see one, remember that you'll lose about a second per dropout.
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Old February 15th, 2009, 01:37 AM   #14
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Perhaps I can just describe my experience with drift, as multisecond drift over an hour is not to be expected. I shoot multi-cam with an XH-A1, HV20, HV30, and recently a Sony Z5U (all 1080 60i). I sync via the camera flash method at the beginning, and check it at the end. I also check the audio waveform pattern match. I was happily surprised to find that all three Canons match to the frame over a one hour tape. The Sony lost one frame in an hour, and an M Audio micro track audio recorder loses 3 frames drift in one hour.

Even with dropouts, I reassemble the usable fragments based on internal time code, and the composite track stays in sync.

Multisecond drift has to be a camera problem or a methodology problem. Hope this helps.
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Old February 15th, 2009, 09:28 AM   #15
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I would have though you would edit for time first, for example compressing, say, a 4 hour real-time event down to close to perhaps a 1 hour edited program length...
Steve... In many cases, events take as long as they take and you need to retain every moment of them... or at least key segments. For example, a wedding is made up of segments. The actual service of the average wedding takes generally under an hour and is something that the couple usually wants captured in its entirety. The reception, on the other hand, can take many hours. For that, only the key elements are preserved, like toasts, stories, cake, first dance, garter and bouquet. Cutting the reception would use a technique like you describe.

It's the same with motor races. Long runs under green, even if apparently boring because there's not passing need to be in the final program whereas laps under caution do not, save pit stops and any incidents.

Hopefully I haven't beaten this to death, but I'm just trying to be as clear as I can (after only one cup of coffee).

I find it interesting that although we work with similar gear and end up with edited moving pictures, how we get there can often be very different from one another.
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