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Audio sync drift problem with HVX200 P2 capture
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Well, there could be a lot of reasons for this. For now we will focus on frame rate.
I’d try another transcode of the media with 23.976 set as your frame rate, not 23.98.
Jeremy
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I’m way ahead of you Jeremy (well, maybe not that way ahead of you. 🙂 I am currently transcoding some clips at 23.976 that I originally transcoded at 23.98. We’ll see if the addresses the audio drift issue. It is a promising theory. If 23.98 is not the real frame rate that FCP recognizes (despite the fact it says 23.98 in the sequence settings, etc.), that could explain it. Especially since clips encoded at 29.97 work fine.
stay tuned…
Ron Dawson
Executive Producer/President
Dare Dreamer MediaCreating films that inspire and encourage the human spirit.
*** Dream Out Loud ***
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[Ron Dawson] “If 23.98 is not the real frame rate that FCP recognizes (despite the fact it says 23.98 in the sequence settings, etc.)”
I know that FCP says 23.98, and in my opinion, it is not a smart move. The real frame rate is 23.976, even though FCP calls it 23.98 (like I said, it’s shorthand in FCP for 23.976). It really does mean 23.976 and FCP will act normally if your movies are 23.976.
If you have After Effects, you can render a 23.98 and a 23.976 movie and you will see that FCP doesn’t handle 23.98 movies properly.
If this doesn’t work, we will try other things.
Jeremy
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HALLELUJAH! EUREKA! LAND HO! Jeremy I could kiss you! No kidding. That did it! I re-encoded two of the problem clips and dialed them in specifically at 23.976 (whereas before I did it specifically at 23.98). Both clips when dragged and dropped into FCP play fine. These were both shorter clips so I’m going to re-transcode the very first problem clip which was over an hour. But, based on these two tests, I think I can officially call you my hero.
When I think about the other “23.98” clips I have that didn’t experience the problem, my guess is that when I created those with MPEG Streamclip, I left the frame rate box empty (which is what I normally used to do). So, the original h.264 files must have just defaulted to their actual 23.976 frame rates. Only recently did I start actually typing in 23.98 into the frame rate field in MPEG streamclip.
If I’m ever in Chi-town again, I owe you a drink! Thanks again.
Ron Dawson
Executive Producer/President
Dare Dreamer MediaCreating films that inspire and encourage the human spirit.
*** Dream Out Loud ***
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[Ron Dawson] “When I think about the other “23.98” clips I have that didn’t experience the problem, my guess is that when I created those with MPEG Streamclip, I left the frame rate box empty (which is what I normally used to do).”
On shorter clips, you probably just don’t notice the drift. The difference between 23.976 and 23.980 is very small. On shorter clips, this difference own’t show up to the eye and on longer clips you will notice this drift as the time will add up. FCP might not play the 23.98 clips back correctly though, so it’s is protocol to put the clips in the proper frame rate of 23.976.
Also, to help you in the future, you might want to look at Grinder or the free Log and Transfer plugin from Canon. Both of those solutions will handle any frame rate shenanigans for you.
Glad you’re up and running. 😉
Jeremy
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Actually, on these two shorter clips (49 min and 21 min respectively) I still did notice the drift. It was obviously much more pronounced on the longer hour+ long clips.
I’ll take a look at the plugins you suggest.
Thx again.
Ron Dawson
Executive Producer/President
Dare Dreamer MediaCreating films that inspire and encourage the human spirit.
*** Dream Out Loud ***
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[Ron Dawson] “Actually, on these two shorter clips (49 min and 21 min respectively)”
Those are long clips! When I say short, I mean 1 minute or less.
Jeremy
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I appear to be having a related problem. However, I’ve used all the techniques outlined above and still have internal sync consistency issues.
The source material is clips from a feature film shot on the Canon 5D Mk2 with the latest firmware update. We used a slate with a traditional clapper to sync up to separate-source audio. HOWEVER, I’m not even at the point of syncing yet. I’m noticing this problem with the clip itself.
Format: 1920×1080 23.976fps progressive
Transcoded to: ProRes (LT)
Using: Canon plug-in (latest version) for Final Cut Pro
Software: Final Cut 7.0.3, Mac OSX 10.6.4
Hardware: 2x 2.4 GHz 8-Core, 8 Gigs of RAM, 2TB internal editing drive, 2 TB E-SATA drive (for backing up camera masters)The FCP sequences are all running at 23.976fps. The clips (as far as I can tell) were transcoded properly at 23.976.
When playing the clip both in the Viewer AND in a 23.976 sequence, the slate is ALWAYS off by one-to-two frames. However, using plosives as a guide (dialog “p”s and “b”s), it appears as though the clips SOMETIMES drift. Plosives can be unreliable (especially if it’s a wide shot).
Please keep in mind:
I’m talking about the CAMERA AUDIO in the clip, NOT another audio source. In other words, the clip IS NOT SYNCED TO ITSELF.The clips are short (4-5 minutes at the long end). They are consistently off (by 1-2 frames) at the top of the clip. I’ve tried adjusting the playback offset but that doesn’t seem to make any difference. The slates are generally well-done (they aren’t half out of the frame or being moved while being clapped), certainly enough to tell when they’re closed.
Any suggestions? I’d love to not have to retranscode everything. Thank you very much.
Sincerely,
Arthur Vincie
Director, “Found In Time”
https://www.foundintimefilm.com
https://www.chaoticsequence.com -
Hi Arthur,
You wrote that the clips were transcoded properly “as far as you can tell.” What does that mean? Is there any chance they WERE transcoded at 23.98 instead of 23.976?
The other question is, does the audio drift get progressively worse, or is it exactly off by 2 frames all throughout?Lastly, is the clip out of synch when played in the Finder or in QuickTime? If so, then at least you know it’s a problem with the clip. If, as it was in my case, you only notice the synch issue within FCP, then you know it’s an issue with how FCP is interpreting the clip, and something needs to be changed with how you created it that will make FCP “happy.”
Good luck!
~ Ron
Ron Dawson
Executive Producer/President
Dare Dreamer MediaCreating films that inspire and encourage the human spirit.
*** Dream Out Loud ***
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[Arthur Vincie] “I’m talking about the CAMERA AUDIO in the clip, NOT another audio source. In other words, the clip IS NOT SYNCED TO ITSELF.”
Is the h264 file in sync?
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