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AMA offset timecode issues–anyone else seeing it?
updated 11 years, 1 month ago
3 Members
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8 Posts
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Hey y’all.
I’m bringing in large ProResHQ files (70 G, 47 min. ish) and they are playing fine on my i7 MacbookPro via Glyph HD. No stutter. BUT. When I check the TC viewer, the four audio tracks all have TC numbers 3 or 4 frames out of sync (+3, +4) with the video track. If I do sellects reel and produce an EDL, the error is perpetuated. The error is consistently the same number of frames off throughout each file. When I check the files in FCP, there is no TC issue.
Any thoughts?
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To add to the info, I transcoded one of the files from ProResHQ to DNx 220X with no problem, and ended up with matching TCs. So, it seems to be happening only with AMA.
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Just out of curiosity: are these files 23.98? Can you reproduce the same issue with source files at a different frame rate?
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I’ve seen a similar issue on the show I’m currently working on. Our workflow is all XDCAM based, and our plan was to ingest on the cheap using all U1 and U2 drives. Mount XDCAM disc, AMA, transcode for offline. The plan was then to assign tape names to each of XDCAM disc, and then use an F1600 deck to batch capture for online. The theory being, save money on ingest buy renting U1 drives for offline, but batch capture the old fashioned reliable way. What we found in testing this workflow was that our timecode was consistently off by 12 frames. Every single clip had to be slipped 12 frames. Weird things is, sometimes 12 frames forward, sometimes 12 frames backward, but always 12 frames.
In doing some investigation, we looked at the starting timecode of the transcoded clips versus the clips when linked in AMA, and indeed the timecode was off. We never modified the timecode so, this was very strange behavior.
I then tested a workflow where I decomposed my sequence for offline. I found that I couldn’t point the AMA linked clips to link to the new offline master clips, but if I made subclips out of all of those master clips, that the AMA linked clip would link to those subclips. I then transcoded those subclips to my High Res workspace, one tape at a time. With all that media now on the high res workspace, I relinked the offline master clips to that it came online perfectly accurate. to expedite making subclips out of exist master clips, I exported an ALE of the bin with my master clips, and then imported that ALE to the same bin, with the shotlog import option “Merge Events with known sources and automatically create subclips”
It’s not the most straightforward process, but I tested the workflow several times and it was perfectly accurate each time despite the straight timecode variations I was experiencing.
Richard Sanchez
Los Angeles, CA“We are the facilitators of our own creative evolution.” – Bill Hicks
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Hey Frank!
No its 1080i, 29.97. I have got some 23.98 lying around on different drives but I just don’t have the time to play around much. Right now, I’m just doing select reels on MC 6 to get my fingers keyboarded up, but I’m still cutting the pieces on FCP 7. If I can get the AMA to function properly, I’ll transcode my sellects and do more exhaustive cuts before sending them back to FCP.
My goal is to slowly work back into MC over the course of this project without impeding the project, and learning the subtitles as I go. It also lets me not worry too much about current bugs.
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[Chris Harlan] “No its 1080i, 29.97. I have got some 23.98 lying around on different drives but I just don’t have the time to play around much. Right now, I’m just doing select reels on MC 6 to get my fingers keyboarded up, but I’m still cutting the pieces on FCP 7. If I can get the AMA to function properly, I’ll transcode my sellects and do more exhaustive cuts before sending them back to FCP.
My goal is to slowly work back into MC over the course of this project without impeding the project, and learning the subtitles as I go. It also lets me not worry too much about current bugs.”
That’s a sensible approach. I was asking because there is a bug with QT and TC in 23.98 files. I run into it every time with subtitling apps and some xml stuff, also confirmed by some developers I reported this to. Thought it might be related but if it’s with 29.97 then it’s something different.
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Richard, thanks!
I fear I don’t have the time to try your workflow because my using Avid here is for my benefit and growth, and not for the project’s. What I will probably do is continue to make sellect reels on MC and send edls to FCP. When I have the time, I’ll transcode some of my projects at night and do fuller edits on MC.
I have to say, I’m enjoying my experience so far.
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[Frank Gothmann] “the subtitles as I go. It also lets me not worry too much about current bugs.”
That’s a sensible approach. I was asking because there is a bug with QT and TC in 23.98 files. I run into it every time with subtitling apps”
That’s funny. I meant “subtleties” not “subtitles,” but I guess either was appropriate.
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