Audio Drift 24PA

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K

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Hi Guys,
I'm running into a problem, where, I've shot 24p advanced footage (as I always do) and just out of Lazyness do "capture now" for about an hour of footage. The problem is, when I'm done all of the audio is about 26 frames or so out of sync. I've noticed that if I capture a small part of the clip the same way ("capture now"), or if I log it and set in and out points for a small part of the clip, the audio stays in sync. My settings are device control: "Firewire basic Non Drop Frame", and my sequence is non drop frame (due to the dvx recording in NDF in 24pa) and my capture preset is the standard NTSC DV preset. I tried putting the captured clip through Cinema Tools to remove the "advanced" 2:3:3:2 pulldown and return it to 23.98 FPS, but the audio was still out of sync. So my theories about the audio drifiting because of the frame rate conversion proved untrue.

I've just never run into this before. Is this something to do with the DF/ NDF timecode issue? I know the DVX does an in camera Telecine Process to get the 23.98 matterial to 29.97, does it then make it DF timecode? It just seems like I should be able to do "capture now" for a long clip and not have the audio go out of sync. I have the proper "sync the footage" boxed checked in FCP HD prefrences. So what do you think guys? Is it my settings? Is it using "capture now"? Thanks so much.
 
Re: Audio Drift 24PA

Note that Cinema Tools can't remove advanced pulldown. You have to capture in FCP with advanced pulldown removal or go to tools > Remove Advanced Pulldown after capture. CInema tools can reverse telecine on regular 24p footage but doesn't work on advanced pulldown.

Not a good idea to capture long periods if you can avoid it. Check 2-pop.com for suggestions on dealing with sync issues since it's been discussed there a lot.
 
Re: Audio Drift 24PA

I agree that it isn't a good idea to capture long clips like that. I just feel it should work.
But are you sure cinema tools doesn't remove the advanced pulldown? I have always shot 24PA because of the "optimal" 2:3:3:2 pulldown -- so if you shoot in 24PA, capture, and then open up that clip in Cinema Tools and check "reverse telecine" -- you'll get a pop up that is titled "Automated Reverse ADVANCED 2:3:3:2 Pulldown". when you're done you get a 23.98 fps file (or whatever FPS you stipulate)

Conversely, if you shoot normal 24P with the DVX100, capture, and then open up the clip and do the same thing you'll get a window titled "Remove 2:3:2:3 Pulldown".

So obviously Cinema Tools can recognise between the two and act acordingly, why do you say is can't remove the pulldown?
 
Re: Audio Drift 24PA

You're right, I just checked, the latest version of Cinema tools does fully support the Advanced Pulldown. I just got used the original FCP and avoiding another step/copy in the process.
 
Re: Audio Drift 24PA

I'm having this same problem with 24PA, but i'm only capturing 5 min clips... Why is this happening to synched audio??? I was told if I didn't use DAT so i would avoid this problem. Anyone know how to fix this??
 
Re: Audio Drift 24PA

Hey,
Well, I've run into this before as well. I solved this problem just by making sure all my settings, from capture to sequence timeline, were consistent with my footage, and working methodically. For example, I solved my above problem (using FCP HD), by simply making sure to set in and out points and properly logging the footage, I also used the "remove advanced pulldown" capture preset as suggested, and it did indeed remove a step from my usual process. I successfully captured about 45 min of footage in one run with synched audio. I had never trusted that option before, and preffered to remove the pulldown manually with Cinema Tools.
Some Questions:
You are shooting 24PA or 24P?
are you capturing/ editing in 23.98fps or 29.97fps?
do you have the "sync audio" option checked in the prefrences?

Another, lesser known, but VERY important thing is the firewire control protocol you are using to control your AG-DVX. the DVX requires the FIREWIRE BASIC protocol to be used, which is not the default. You can find a list (pdf) of qualified FCP HD devices and their required protocols at:

http://www.apple.com/finalcutpro/specs.html

When I started to use the proper protocal, it solved a number of issues for me, including sync problems.

Hope that helps.
 
Re: Audio Drift 24PA

Hey -
Thanks for the reply. Yes, I've solved a lot of problems too by methodically going though my settings and making sure they all match. But usally when I figure one problem out, another comes up.

I am using the "remove advance pulldown" and my image looks good. We shot 24p advanced DVC Pro50. I'm capturing and editing in 23.98 and I HAD the "synch audio" button checked, but now it's unchecked. Neither seemed to make a difference. Also I don't think I should use the basic settings, but i could try it... I've rented a Panasonic AJ-SD93 deck for the weekend to capture 27 hours. I have to return it Monday so I'm sort of panicking cause it's expensive....

For now I'm just capturing 3 minute clips and it seems to be fine. I wanted to do this later and be lazy and just capture big chuncks like i've done in Avid. I'll go though my settings once again but they all seem to be corropsonding. Any in particular I should look at??
 
Re: Audio Drift 24PA

I am having a similar problem capturing footage shot in 24P (standard) on a DVX100A. I was capturing whole tapes onto an external hard drive using the "capture now" function in Final Cut Pro 4.5 on an Apple G4 1.33, and discovered that the audio was out of sync by about 40 frames (with audio leading). After reading up on it in this forum it seemed that trying to capture 60 minutes of footage with "capture now," while neglecting to set an out point, may have caused this sync problem. Could it also be because I selected "Firewire NTSC" instead of "Firewire NTSC Basic" as my device control preset, as you have suggested? Does this mean I should capture my footage again with the correct device control preset and in more moderate-sized clips? (Note: I set the capture preset at DV NTSC 48 kHz.)
 
Re: Audio Drift 24PA

Yeah,
Unless you don't mind manually synching your footage, I would say go back and recapture. You may want to first experiment with using firewire basic first and see if that solves it. Like I said, using firewire basic as prescribed by the final cut info page solved a number of issues. But I was not able to capture that amount of footage using "capture now" without sync issues. I suspect it's the frame rate conversion going on in the camera and how it's captured. Set in and out points for the beginning and end of your tapes, log it, and fire away. I did that with no more problems, and just used "capture now" to grab some bits at the very beginning and end of the tape (short bits with, curiously, no sync issues). Which is really my fault for not running a good bit of post/pre roll. Another thing of note, is that in 24p mode (either one) the dvx records non drop frame timecode, when I know standard NTSC is drop frame. I have set my control protocal and timelines to be drop frame as well to match the camera. Though, I don't know if this is necessary.
 
Re: Audio Drift 24PA

Pardon, I meant I set my capture and sequences to be Non drop frame, not drop frame. Sorry.
 
Re: Audio Drift 24PA

Thanks, K, for your response - I think I'm getting to the bottom of this now. I just want to clarify a couple of things. In your experience, then, has the audio/video sync been okay when capturing over 50 minutes as long as you set in and out points ? Also, if the DVX records non-drop frame timecode, do you think the timeline in FCP should be set to non-drop frame timecode as well? You said that you set your timelines to drop frame "to conform to the camera", which confused me a bit. What timeline setting then has worked for you in FCP when working with DVX footage?
 
Re: Audio Drift 24PA

K - thanks you just answered one of my questions while I was busy writing it down (about the drop/non-drop frames).
 
Re: Audio Drift 24PA

I noticed the audio drift on my last project while editing, but when I outputted to tape and DVD everything was in sync.
 
Re: Audio Drift 24PA

Make sure that you're watching and listening to the same device. (i.e. output video/audio to firewire video camera or watch on the computer) If you output video to the camera and listen to the computer audio then there will be sync issues.
 
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