Quicktime playing back speed, and audio sync

Question

Hello,
I'm trying to use QTPro instead of iMovie to digitize ntsc video because it produces a single DV file instead of multiple files in iMovie. This saves the rendering process in iMovie. These files need to be a single video file and are used in a chase computer for audio post work. Typical program lengths are between 1 and 3 hours, sometimes more.
When playing the files back in QT the audio progressively drifts even though the firewire box has a switch for "locked audio" that supposedly deals with long DV audio drift.
Another problem that may be related, but certainly can't be good for post work, is that the Movie Info window shows a movie rate of 29.97, correct, but a playing rate of 30. I can't figure out how to get that to play at 29.97.
One last question - the QT record settings have different resolutions (640xxx?) than the native DV resolution of 720xxx, and seem to have a slightly different pixel aspect ratio as well.
Any ideas about these issues? It's messed up my workflow for now, as the iMovie solution has an extra step that takes up double the disk space and extra time.
Digitizing box is a Canopus ADVC-100 with an external 3.5" firewire drive for video, no other apps running at the same time.
Thanks
H
G4-17 Powerbook   Mac OS X (10.4.6)  

Answer 1

I'm definitely at 48k/16b, with locked audio on the Canopus.
Sounds like you've got it covered, then. Not sure what else would be causing the A/V drift then, assuming "lock" circuit is functioning properly.
I watched the playing rate and it's mostly at 30 with an occasional dip to 29.75, possibly averaging to 29.97. Hopefully it's correctly playing 29.97
Your upper and lower observed excursions exactly match my own.
The older projects were indeed done with an early version of iMovie and would segment at just under 10 minutes - the 2G limit.
Correct. On mine the "just under" 2 GB limit equated to 9'11" for the first break and 9'8" for each additional. Not sure how exact this carryover is between machines and external drives.
I did a test today using my current version, iMovie HD 5, and it segmented a 2h10min program at just over 1hour per segment. Do you happen to know if the newest iMovie corrects this?
Am wondering if this test is repeatable and/or consistent between capture of different material. Have noted two instances that seem to cause segmentation and/or total termination of capture. One is a "weak" drive sector that passes read/write tests (i.e. test usually done with multiple but limited re-write attempts) but drops a frame during actual capture and trips termination on my older G4 laptop (using older version of iMovie with preference set to do this). As to current iMovie version (v6.02), would assume this could happen if "automatic scene detection" is turned on and a dropped frame is detected. In addition, if this option is turned on, a "time limit" for capture can then be specified. Can't remember if these preference options were included in previous versions of iMovie. You may want to check on this possibility.
I can certainly try the Vidi app you mentioned.
Application is a basic, dedicated, "no frills" utility with fewer "platform limitations" (it works on older platforms/OS) than iMovie. I find it very handy for mobile capture using my old laptop. Here is the VersionTracker link if interested:
http://www.versiontracker.com/dyn/moreinfo/macosx/18234&page=2
After updating various things I tried using QTPro recording as a test, and after about 1h50min it crashed, leaving the file unfinished and useless. Is there a reputation with QTPro recording? Is it rumored to be unstable? I'm a bit nervous using it now. I keep my systems streamlined for audio post, so I doubt it's a conflict.
Tend to consider it "an afterthought" added to the latest version of QT and as such, a "work still in progress." Frame rates have greatly improved with the last few updates but, like you, I still consider it more of a novelty at this time -- handy for some usese but not something I would trust for precision work.
I solved that by showing package contents of the iMovie project and removing the media clip, a dv file.
I certainly see no problem with this approach if all you want is access to the "raw" material in a file format and especially if you keep it on the same drive. (I.e., all your are doing here is changing the VTOC pointers to the data and not actually copying and/or moving any vast amounts of data, not to mention, it additionally saves drive space.) Basically, the export/copy approach means re-writing vast amounts of data which is directly related to speed of your external drive, CPU and the speed of your target drive. For some purposes, the creation of a reference file may be handy. But even here, you are usually just postponing an inevitable time delay somewhere else in your work flow.