audio sync problem with DVX100B
by Redford Givens
on
Aug 14, 2008 at 5:17:42 pm
Audio out of sync.
Using Panasonic DVX100B. Set for 24p advanced pulldown.
We are getting timecode breaks that seem to coincide with the audio sync problem. This is to say that the capture after a timecode break is sometimes out of audio sync.
Is the problem really timecode breaks?
How can we prevent timecode breaks?
Can we set a DVX100B to only read the timecode on a "blacked" cassette? It seems that if we can force the camera to accept the previous timecode there would be no breaks since the tape was completely "blacked." Don't know if this is possible?
We are capturing via firewire to a MacPro 266Ghz dual-core. We capture with FCP and store the media on a seperate internal drive.
Re: audio sync problem with DVX100B by Redford Givens on Aug 14, 2008 at 5:32:40 pm
What's a cadence break?
When a timcode break is detected by FCP 6.0.1, it searches until it finds a new code to begin capturing again. There is a gap where the timecode break occurred.
The real problem is that clips sometimes, but not always, have audio sync problems associated with timecode breaks.
Re: audio sync problem with DVX100B by Michael Sacci on Aug 14, 2008 at 5:54:07 pm
To prevent TC breaks the camera needs to be set on REC REGEN and as long as you are just stopping and starting without rewinding and forwarding you should not have TC Breaks. You get your breaks when the camera is set to FREE RUN.
One thing to try is to make the effected clips off line and then recapture them, but change the TC of the In to 3 seconds later. (if that works and you miss something you need turn 1 or 2 seconds later)
Re: audio sync problem with DVX100B by Jeremy Garchow on Aug 14, 2008 at 5:57:44 pm
If you are removing pulldown on the fly, and trying to capture a whole tape, the cadnce might not be consistent across the whole tape if you have started and stopped the camera during recording. You need to log and tranfer individual clips, especially during pulldown removal. Trying to capture one whole tape while removing pulldown will result in errors.
Re: audio sync problem with DVX100B by Redford Givens on Aug 14, 2008 at 6:29:35 pm
By starting and stopping, do you mean shutting the camera down (as at end of day's shoot) and restarting next day? Or will merely pausing the camera between takes cause problems?
Does cadence mean the sync between video and sound?
Re: audio sync problem with DVX100B by Jeremy Garchow on Aug 14, 2008 at 6:40:04 pm
[REDFORD GIVENS]"By starting and stopping, do you mean shutting the camera down (as at end of day's shoot) and restarting next day? Or will merely pausing the camera between takes cause problems? "
Both.
[REDFORD GIVENS]"Does cadence mean the sync between video and sound?"
No by cadence, I mean pulldown cadence. The pulldown is added to 24p so that it can be recorded onto 29.97 tape. The cadence needs to be detected by FCP and once it starts removing the pulldown frame, it will continue on the same pattern across the tape until it starts. If that cadence is not consistent, FCP will start removing the wrong frames and also it might choke as it sees it's not removing the proper flagged frame. Make sense? Also, a break in the control track will happen when the camera is turned off for whatever reason (such as changing batteries).
Re: audio sync problem with DVX100B by Dave LaRonde on Aug 14, 2008 at 6:43:10 pm
[REDFORD GIVENS]"Does cadence mean the sync between video and sound? "
You're shooting 24pa on a DVX and you don't know what a cadence is? It's time to do the reading that you SHOULD have done before you shot a single second:
Re: audio sync problem with DVX100B by Redford Givens on Aug 18, 2008 at 3:01:32 am
Thanks for all the suggestions. Before coming here we had Apple and Panasonic double check the settings etc. There is no problem with the camera. The problem is the way FCP captures after timecode breaks.
Michael Sacci provided the solution.
To prevent TC breaks the camera needs to be set on REC REGEN and as long as you are just stopping and starting without rewinding and forwarding you should not have TC Breaks. You get your breaks when the camera is set to FREE RUN.
We ran a cassette with more stops and starts than a traffic jam in LA. No problems PROVIDING we do not capture (say half a cassette) and then rewind to the end of the capture and shoot more video. That almost guarantees a timecode problem with a sound sync disaster.
Starting and stopping the camera, even multiple power downs have no effect unless the tape is rewound to continue shooting after the first capture. So long as we continue recording without rewinding there are no timecode breaks.
We were capturing after every shoot, even 15 minutes, and then using the rest of the cassette the next day. This was apparently the cause of our troubles.
Thanks to everyone for the ideas.
Incidentally, I was somewhat aware of what a cadence is, but without the right word. Thing is I count on robots to keep the frame counts right. If Apple and Panasonic cannot get the settings right, we are all lost.
Re: audio sync problem with DVX100B by Dave LaRonde on Aug 18, 2008 at 4:09:28 pm
[Redford Givens]"....I count on robots to keep the frame counts right. If Apple and Panasonic cannot get the settings right, we are all lost. "
Remember that robots are machines at heart. Machines can and do screw up. So it you really are going to rely on them, you WILL be lost.
On those very rare occasions when I have to deal with 24pa, I'll stick with the tried and true: DON'T capture entire tapes. DON'T capture groups of takes. Log individual shots only.
Yes, it takes longer, but the batch capture is a breeze, and it always comes out right.
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Re: audio sync problem with DVX100B by Redford Givens on Aug 26, 2008 at 8:22:25 pm
Re: audio sync problem with DVX100B
by Dave LaRonde on Aug 18, 2008 at 11:09:28 am
On those very rare occasions when I have to deal with 24pa, I'll stick with the tried and true: DON'T capture entire tapes. DON'T capture groups of takes. Log individual shots only.
Yes, it takes longer, but the batch capture is a breeze, and it always comes out right.
Dave LaRonde
Thanks Dave. You are exactly right about batch capturing.
Now that we figured out how to do batch captures, the sound and TC problems have vanished.
Batch capturing saves us time because there are many bad takes that have to be removed. With an accurate video log we just capture the good stuff and it saves some time.
One thing though, how can we use the original TC to determine fine editing. Some clips have a few seconds in the middle that need removal. As it is we must play the clip to find these points. If we could use the camera TC we could stop a few seconds ahead of the edit and save a lot of time going back and forth until we find the precise cut points.
Thanks to everyone for the suggestions. We went round the bend with sound-sync and TC breaks, but due to you folks we now know more about TC breaks and sound-sync problems than we ever wanted to learn.
You fellows probably already know this, but it's worth knowing.
The batch capture in FCP for the final clip on the reel should stop a few seconds before the taping ends. Trying to go all the way to the log out on a final clip can cause a TC break if your end count doesn't fall in the right spot in the cadence. If there are some seconds recorded on the tape after your out point and it falls in a bad cadence position FCP will add a frame or so to make it right. When we set the capture to the very end of the shoot and it landed on a bad cadence frame, no capture was possible until we moved the out point back a few seconds.
For some reason, I always seem to find the most aggravating glitches in a program right off to bat. That's why I hate robots.
Re: audio sync problem with DVX100B by Redford Givens on Sep 1, 2008 at 3:48:29 pm
On those very rare occasions when I have to deal with 24pa, I'll stick with the tried and true: DON'T capture entire tapes. DON'T capture groups of takes. Log individual shots only.
Yes, it takes longer, but the batch capture is a breeze, and it always comes out right.
Dave LaRonde
We are using the batch capture method and it works pretty good, but not perfectly. To wit: We are no longer getting timecode errors. However, FCP claims to be detecting "cadence breaks" and refuses to capture the clip.
By resetting the in out points, we have captured these clips WITHOUT the cadence break.
Logically this tells me there was no cadence break in the first place because we extended the capture on both ends and got the clip.
Re: audio sync problem with DVX100B by Dave LaRonde on Sep 2, 2008 at 2:36:17 pm
It's also why it's always good practice to let the camera roll for five seconds before any significant action begins and five seconds after the action ends in any shoot where you work off a script.
If you shoot events this practice may not not always be possible, but even then you can still do it most of the time.
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Re: audio sync problem with DVX100B by Redford Givens on Sep 2, 2008 at 5:46:41 pm
It's also why it's always good practice to let the camera roll for five seconds before any significant action begins and five seconds after the action ends in any shoot where you work off a script.
If you shoot events this practice may not not always be possible, but even then you can still do it most of the time.
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
We are learning. The batch capture is definitely an improvement over trying to get the entire reel. It saves time by eliminating shots that were bad for other reasons. By capturing a few seconds on both ends of clips, there isn't much cutting to do.
If I were younger, the thought of going pro in this business would appeal. As it is I'm an old codger who takes One on One lessons from Apple and comes to forums like this to solve specific problems.
Manuals sometimes help, but they can drive one to madness trying to find the specific solution you want.
The people who write manuals could do the world a service by inserting a comprehensive GLOSSARY at the BEGINNING of the book. Manuals often use hard to understand Hollywood terms or professional definitions without much explanation.
