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Audio laybacks give me headaches: a plea for help DAW Software
Old 10th September 2011
  #1
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Audio laybacks give me headaches: a plea for help

The job:

Ingest a german stereo mix from a PAL digibeta. Convert to NTSC, and lay back to tracks 3 and 4 on an NTSC digibeta (1 and 2 are english).

The problem:

The sync is drifting back and forth; from perfectly in sync, to 6 frames out either side. It's a pretty rhythmic drift, almost like a sine wave.

I've digitised sample segments from the PAL several times; all passes line up with each other in PT.
I've digitised sample segments from the NTSC (english) several times; all passes line up with each other in PT as well.

When i convert the PAL mix to NTSC (using 46,034 PAL to NTSC sample rate convert in PT import audio), i then try to line up the newly converted audio with the guide sample i digitised from the NTSC tape. The sync drift is happening right there in my session.

So, it seems that my machines are locking up ok, but somehow the pulldown is causing it to drift... Although i've used PT SRC many times in the past with no problems.

Any ideas? The only thing i can think of is that the PAL tape was badly converted from NTSC in the first place... but that means more work for me.

Any other ideas?

Thank you all so much,

Roger
Old 10th September 2011
  #2
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gsilbers's Avatar
 

well youll always have to ingest both versions. because most of the time its not going to be always perfect sync. the more older the program the more edits down the line.
but..


obvious questions here but:

are u using any pull down settings in your pro tools session ? (settings menu, down on the right)
sometimes pro tools imports these settings by accident.

NTSC and PAL timings on the tapes are different right?
(there are ways of making pal tapes the same length of the ntsc)
there are ways of converting to pal which itll be longer than the ntsc (and shorter).

then the obvious things like is it drop frame on the ntsc?

whats the time difference between the ntsc and pal tapes?


how are you working?
with from digibeta to digibeta or ingest everything to pro tools then output?


does the video have motion lag? (some pal convertions fukup cause they are done with Final cut or on another crappy way from folks who dont know)

what show are u working on?


this is everyday for me for a very long time. and i even do homework in gearslutz
so any questions let me know.
ive sent tons of material to germany so im familiar to the german standards... ( toughest in the world! )
Old 11th September 2011
  #3
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Quote:
are u using any pull down settings in your pro tools session ? (settings menu, down on the right)
sometimes pro tools imports these settings by accident.
Nope, i created a fresh session for this, and no PT pull down settings are in effect.

Quote:
NTSC and PAL timings on the tapes are different right?
(there are ways of making pal tapes the same length of the ntsc)
there are ways of converting to pal which itll be longer than the ntsc (and shorter).
That's right, the times are different. Is it called dupe frame when PAL is made to match the speed of NTSC? In any case, we don't have that either. And with my pulldown of the PAL, the overall duration is pretty much the same after 1 hr 55 of program.

Quote:
then the obvious things like is it drop frame on the ntsc?
The NTSC is drop frame, and i adjust my PT TC settings to match when i'm linked to the NTSC deck.

Quote:
whats the time difference between the ntsc and pal tapes?
I couldn't tell you the difference atm, the tapes are at work. But, as before, once pulldown is applied, overall program durations more or less match.

Quote:
how are you working?
with from digibeta to digibeta or ingest everything to pro tools then output?
I'm recording into PT, then applying pulldown on Import Audio, then output. Actually, i'm not confident that PT is getting the same sync source as the PAL digibeta. The thing is, i don't think the room is set up for that.

Quote:
does the video have motion lag? (some pal convertions fukup cause they are done with Final cut or on another crappy way from folks who dont know)
I'll check it out when i look at it next, but that's something i'll check in future.

Quote:
what show are u working on?
It's a very old film called "Fanny". So i guess editing might be the way to go.

Thanks so much for your response. In the facility where i work, i'm the only one who deals with audio laybacks, so i don't really have a senior who can help me out. And google comes up with very very little about tape tech stuff.

Another thing i noticed just after posting this q: at one point (between my NTSC guide and my pulled down PAL), a glass putdown is 1 second out of sync. About 5 seconds later, another glass putdown is perfectly in sync. And now that i think of it, i do recall hearing some slight audio stutters in my PAL ingest, which i passed off as being because it's a very old audio track that's been remastered. So i guess i'll have to record the whole NTSC guide and cut to fit. Sigh.

Thanks again, and if you have any more wisdom, it is greatly appreciated!

PS: I've heard a lot about german QC standards. In one aussie film, the opening scene was in cicada-heavy bushland. They sent it back as being distortion. Upon being told it was cicadas, and part of the sound design, their response was "it is very annoying. take it out"
Old 12th September 2011
  #4
I think you might find editing the only way.

Your problem is to do with how they grade the picture to go from film to tape. They need to grade each shot as they go through the film, rocking n' rolling over the cut and dropping-in on tape. In the process they quite often end up losing frames and in some instances gaining time. Mostly it's cutting time out of the mix to fit picture but you may find you haven't enough audio and will need to copy and fill sections.

That's my experience anyway.
Old 12th September 2011
  #5
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gsilbers's Avatar
 

interesting.

well. 1st thing is that even though i understand what u are calling pull down , i think its the wrong way of calling it.

pull down is only referred to when you do a .01% so from 30 frames per second to 29.97d.

when you go from NTSC/23.98/59.94 to PAL/50i/25p and vice versa is called
varispeed. well, thats what we call it in LA (or standards conversion in the tape world)

anyways. i know you are doing it right.. ntsc>pal in pro tools..

but i think its the source. if you say its an old film and it goes back and forth in sync.. then the source might of been a 1inch tape which then was transfered to D1, then to D2 and then to ntsc.. but at the same time someone else whent from 1inch into digibeta and each verison there are cuts and edits and things like that.
just kidding.. dont know your situation but we get things like this ALLL the time.
we dealt alot with universal's/nbc recovery program trying to restore and save different masters after a fire broke at the universal lot where the vault is and they lost a lot of masters. (they should have a vault underground in kansas as FOX does)
so we got bits and pieces of different masters to create new masters and your type of situation happened a lot.
even for FOX and disney too. theyll have old masters and the audio (grmn,las, ita, etc) does match to it or matches but it goes back and forth out o sync.

for engineers working on current projects this might sound crazy and IT HAS to be the equipment or the setup but if you have worked with old sources then automatically you know old masters of the same film/tv show are not going to match. happens all the time, no matter what studio/network etc.
itll be close, or it will be crazy like double pull downs. who knows what history there is. sometimes it matches perfectly. other times its just missing sections cause there are different edits.

i worked on a 1960s FOX movie called the shrine (or something) .... master where digis.
for the longest time i didnt see why the audios did not match. no matter how much i edited, same dialog line will be out.. in the same [email protected]@@

turned out that back in the day they shot the movie twice!!!!
one take with one camera and another take with another type of camera.
like A roll and B roll.
the masters do not say any of this info and studios long forgot about this.
and of course FOX did not understand what was i saying.
so i had to send quicktimes of the same scene but different versions where they could see that one of the extras in a scene of hunderds of people was doing something different!!!

anywaaaayyyyyyyyyssssss......

each time its going to be different but long story short. you have to "conform" or edit your project. capture the video (QT) of the master you are going to conform to and load the new audio and do cuts all around. sometimes its one cut every 20 minutes, other times every 5 minutes.



match the music and effects but keep an eye out for dialog. to do it faster, just match music and effects as fast as posible and then watch it though to see if dialog is in sync.

also, watch out with reference. if you dont have ntsc reference just set it to internal. (light will blink) but its not going to be a major problem if you are only capturing audio, just set PT to capture in ntsc as well.
depends on the type of digibetas you have.
most digibetas just do ntsc OR PAL. but there are mods available to change it to either pal ot ntsc.
if the audio comes from an ntsc digi then set pro tools to ntsc 2997
and pal if its a pal digi.. obviously
point is that u do the varispeed after you capture it not while you capture the audio. (just trying to be clear.. sorry if its obvious)

when u capture video u can use quicktime pro or final cut but make sure your capture settings are pal (or ntsc) dunno the details of your project but that it matches the outcome of your project and the tape deck its coming from.

capturing video is much better than just audio. cause if its going in and out of sync then you wont tell if the dialog is in sync if its another language.
if its the same language then not need for QT video. match audio to audio.

btw... We also got an email from (i think germans.. or japanese.. i forget)
of a similar thing with cicadas/insect noise background.
but once we told them its how the ambience is and they where happy. (i guess)
and it was the series bones.. so its not like an indie weird film or something.


hope that helps.. if not .. then hope u enjoyed the stories.
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