Audio drift in 23.98 timeline REDUX

[The Edit doctor]

Nathan,

Okay, if you’ve recorded separate audio during your shoot and then hand synced this audio via clapper in FINAL CUT PRO and it was actually in sync then the audio was most likely recorded AND stamped at the same rate. For instance, recorded at 48 and the data information stamped on it is 48. If it was recorded at 48.048 then the data is stamped at 48.048. Final cut resamples alternate data rates to your timeline rate on the fly. 48.048 becomes 48 but the SPEED remains the same. Did it have a green bar above it in the FCP timeline or simply nothing.

First please confirm the data rate of the recorded audio AND what the stamped version rate is. Hopefully you know this info. open a file in FCP and read it’s audio rate from the browser AUDIO RATE category.

Now, I’m lost here. Did you edit this material to the picture in sync and give an .omf to the protools guy? or did the protools take your original audio and create a mix and give you .aif files of final mix.

If he brought in the original files and they were stamped 48.048 but recorded 48 they play slower IN PROTOOLS- they could play the pulldown speed twice over. so too slow or they could be pulldown speed – it depends on what the ingest choice for audio was.

This does not work the same way in FCP. Final cut plays audio recorded 48 but stamped 48.048… faster. The speed to speed up 23.98 to 24 to be exact.

So, is this mix finished and was insync with a protools picture? I believe you gave him a quicktime movie but at what speed. 23.98? 24? 29.97 tape? I know you’re looking for a simple answer here but this has gone so far without enough technology decisiveness.

So, again, tell me about the quicktime of the picture (speed). Tell me if an omf from you was given to protools or he used a list and went to the original tapes – Don’t ever do this in a low budget world… use the omf fyi.

Now if you’re still at the protool mixing stage and the sound is messed up…tell me that as well.

Mike

[Nathan Shuppert]

Mike–here’s a re-post of the setup:

I shot footage on the Panasonic P2 camera 720p 24p Native setting in the camera. Boom mic and lav audio was recorded directly into a Pro Tools session. Camera Ftg imports fine back into FCP via P2 import. Throwing it into a 23.98 timeline using DVCPRO HD 720p60 codec, 48khz/16 bit. Audio and video both play great with no rendering needed. Here’s the problem. When I import the Pro Tools audio back in to FCP and sync up to the slate clap, the audio drifts. Starts out fine and in sync, but over several minutes it drifts. We’ve tried everything we know to make it right and so far, nothing is working.

and here’s more pertinent info…

i’m dealing with 2 separate audio sources: camera audio, which stays in sync with picture, and audio from a Pro Tools multitrack session which was recorded during the actual shoot (the shoot was at a recording studio) . there aren’t any OMF’s being dealt with here.

my audio guy is bouncing the original session audio(boom on ch1, lav on ch2) out of Pro Tools, giving me 16-bit, 48kHz aiff files.

When I import the Pro Tools session audio back into FCP and sync up to the camera audio using a slate clap, the audio drifts.

thank you for your time…

Nathan

[Shane Ross]

Recorded on set using a proTools session. What were the settings for this session? The framerate? 23.98? 29.97? Because audio mixed at 29.97 will lose sync when dropped into a 23.98 timeline.

Shane

Littlefrog Post
http://www.lfhd.net

[Steven Gonzales]

What were the setting that the sound was recorded into protools, and what was the protools sync clock?

I believe in a previous thread, you said that the protools audio when placed in Final Cut was slow by .1%.

So between the live event occurring (sound to protools, video to DVCPRO at 23.97 (29.97)), either the video got faster or the sound got slower. Or the sound was originally referenced to a faster clock, and by the time it got in your sequence, it was referenced to a slower clock.

I think we need more information on the protools session: how was that session set up, and what was the clock source?

[Nathan Shuppert]

Unfortunately his settings were 29.97 DF when he recorded the session.

This has become quite a clusterf***. I need to get the session audio out of PT so I can cut the show.
The question now is what is the proper way to convert/export the PT session audio it so it will sync up with my picture in FCP.
Not sure if it’s even possible. Still researching–surely this has happened before to folks using P2 and with an external audio source.

Any ideas would be helpful.

[Nathan Shuppert]

We are not sure what the clock setting was. Trying to find that out now.

[The Edit doctor]

Okay…

Directly INTO protools. Interesting.

So, Protools session at 29.97 recording 48 audio. This is correct. Shane was actually incorrect there previously. 29.97 recording onto say a DAT tape IS the same as 23.98. They are both VIDEO RATE. It’s the timecode numbers that count different but the time and speed are the same. so lets just call it VIDEO RATE.

30fps is the same as true 24fps. We’ll call that FILM RATE. This plays faster by .01%.

in this scenerio your protools guy MAY be adding pulldown to the audio on the BOUNCE OUT. He shouldn’t be doing this.

Is the audio drift getting ahead of the picture (happening before the mouths move) or after the mouths move.

Try this

Choose a long shot. Take the audio and sync the clap with the shot.

Audio faster than picture: go to SPEED type 99.9% Try that.

Audio Slower than picture: got to SPEED type 100.1%

Now, if neither of these are working… there’s something more. Sample rates were recorded or output differently that you are told.

Tell me if audio is faster than picture or slower.

Mike

[The Edit doctor]

Okay…

Directly INTO protools. Interesting.

So, recording 29.97fps and recording 48 audio. This is correct. Shane was actually incorrect there previously. 29.97 recording onto say a DAT tape IS the same as 23.98. They are both VIDEO RATE. It’s the timecode numbers that count different but the time and speed are the same. so lets just call it VIDEO RATE.

30fps is the same as true 24fps. We’ll call that FILM RATE. This plays faster by .01%.

in this scenerio your protools guy MAY be adding pulldown to the audio on the BOUNCE OUT. He shouldn’t be doing this.

Is the audio drift getting ahead of the picture (happening before the mouths move) or after the mouths move.

Try this

Choose a long shot. Take the audio and sync the clap with the shot.

Audio faster than picture: go to SPEED type 99.9% Try that.

Audio Slower than picture: got to SPEED type 100.1%

Now, if neither of these are working… there’s something more. Sample rates were recorded or output differently that you are told.

Tell me if audio is faster than picture or slower.

Also – can the P2 actually record true 24 or is it only 23.98. ANYONE?

Mike

[The Edit doctor]

Sorry guys… my first post didn’t go through… and then I changed and added a couple of things and then they both went through UP THERE…

Sorry

[Shane Ross]

I’ve been wrong before.

I just know that on one show I was on, the ProTools editor edited using a 2.97 timebase and when I tried to link that to my 23.98 cut, sync drifted. Once they adjusted it to a 23.98 setting, it sync’d just fine.

Shane

Littlefrog Post
http://www.lfhd.net