film print sound 2 frames early

[minister]

hi all!

we printmastered a film at 29.97. everything was in synch. to check, we played back from the DMU, there is supposed to be a 2 frame delay the dolby tech told us. we couldn't really see it. but ok... (you'd think the director or myself could see it.) the MOD gets to the lab and the frame counts match on the sound negative and the film negative. on first viewing the film print, the sound is 2 frames EARLY. lab said it was film projectors, looping, etc. (if it was late, i guess we could attribute it to the difference between light and sound speeds) but it was seen on 5 different theaters. each one, 2 frames early.

i know you don't have all the info, but anybody run into this before? was there a mistake made in the DMU? is it a lab thing? something else?

thanks!

[The Chinese]

Minister-

the first thing that comes to my mind is this:
Did you use HD monitoring during this mix? if so, what ti projection or LCD/Plasma based? Again if so, there's your 2 frames... all HD LCD/Plasma/projectors are out of sync 2 frames, which would make your audio 22 fr early.

as for the DMU, Yes the Dolby op is correct, there is a 2 Fr offset that occurs when you encode and then decode the signal. *IF* you coulddn't see it, id be concerned that something went wrong somewhere....but mostlikely not with the DMU. there could have been an offset programmed into your audio chain? Or even more likely, a discrepancy in the Viddeo used for playback and the actual footage of the Film. I'd check those areas first...

-Todd A.

[minister]

hi todd,

QT was a SD 29.97 played out of a genlocked card. monitoring for sync was done on a regular panasonic NTSC monitor. the director watched a plasma, but the offset had been caculated (in VVTR). THEN, we printmastered using a sony HD projection system 9in a place that has never had a sync issue). the last film that was done in exactly this setup was not 2 frames off. furthermore, i lined up the sync dialogue and fx by starting with a 24FPS quicktime viewed on the computer monitored. once i had the converted version, i locked my regions, pulled down by .1% and mixed to the 29.97 version.

yeah, the dolby tech and their units i believe are technically together... but i thought about this because i had seen the 2 frame dekay with the last film, but not this one.

the movie is in sync pip to pip, so, the lab put the audio 2 frames early and it all syncs. the DVD's generated off the same files are in sync, but that is a different kettle of fish... and, the dirctor said that now that the SR•D is in sync, the SR is a little sluggish. is that the nature of SR?

given what i just said, do you still think it is the displays?

thanks for the thoughts.

[The Cobbler]

I may be pointing out the obvious, but on the DMU it is only the Dolby Digital Monitor/play and SR monitor/play monitoring modes that have the 2 frame delay. The "Line in" and SR monitor(AC3 bypass) are not delayed.

Is it possible that you were monitoring audio in one of these modes?

[bigbadhenchman]

yeah, the dolby tech and their units i believe are technically together... but i thought about this because i had seen the 2 frame dekay with the last film, but not this one.

If you didn't notice the delay durifn the printmaster, then that would mean the audio was 2 frames early, making it look in synch using the DMU.

[minister]

hey guys: i am sure that the DMU is correct and that it was probably done correctly. sorry i can't be more scientifically precise... it seems like it must be either a video monitor path problem or a lab slip up. but check this out. at my studio it was in sync. then, we checked the mix and made adjustments and it was in sync. then, when we printmastered sometimes it looked sluggish -- which would be attributed to the 2 frame delay of the DMU encode/decode. anbd i know that the AES stream out of the DMU is not delayed in any way. so the the sound negative should be a direct representation of what was ptinmastered.

we're gonna check again at the dubbing place and if it is in sync there, they use CRT video monitoring, then the lab must have slipped the sound by accident. i'll let you know.

[Frank Kruse]

wether the lab made a mistake is easy to check. the digital optical neg is synced up using the 2-pop visible on the analogue optical track. get your print and check where you see the 2-pop (remember that on a print the optical track is shifted to run in sync at the optical head´s position. If it´s in the correct position it´s either the editor to be blamed who put the 2-pop in the wrong position or a play-back device on the stage while masterring didn´t run in sync.

frank.

[Frank Kruse]

wether the lab made a mistake is easy to check. the digital optical neg is synced up using the 2-pop visible on the analogue optical track. get your print and check where you see the 2-pop (remember that on a print the optical track is shifted to run in sync at the optical head´s position. If it´s in the correct position it´s either the editor to be blamed who put the 2-pop in the wrong position or a play-back device on the stage while masterring didn´t run in sync.

BTW: the 2 frame delay od the DMU during the mastering is very visible. If you didn´t see it your playback sequence was out of sync in the first place. other option would be that the final print is different from the print you mixed to.

frank.

[minister]

hey folks... a little weirder than i thought. turns out that the LtRt off of the MOD plays fine as directly transferred by the lab. the SR•D, however, is 2 frames early. so, they decided to cleave the 2 frames so that the SR•D is exact, but the LtRt (anaolog optical) is a little sluggish. everything was checked and rechecked at the lab. it isn't a "projector loop" issue either -- played the same in 5 theaters.

i am sending the MOD to the Dolby tech to see if we goofed somhow in the printmastering -- we did do additional, separate passes for the LtRt to correct some steering issues.

stay tuned...