Sync issue over frame rate

[Johnny St.Ours]

This is embarrassing, but in a recent 2 camera shoot, my Red was at 23.98 and the other at 24fps. I had the conversation with the sound guy, and we set it to 23.98- somehow I guess I thought the other operator was there on the decision.

Anybody have any ideas on how to sync 'em up?
Any tips much appreciated

 

[MichaelP]

What are you using for NLE?

Michael

 

[Johnny St.Ours]

Final Cut.
First I tried Redcine to render out the 24fps as 23.98, but it's a live show, and the clip is an hour and a half long- Redcine stopped after 'bout 25 minutes.
I tried Apple's Cinema Tools last night on the H proxies, but they just show up green in FCP, even after rendering. I don't mean they have a green bar over top of them, they ARE green. But the browser bin shows them as 23.98, or 24 (I tried conforming each to each) and the sequence time base corresponds, too.

 

[Jean Déraps]

If I am not mistaken, you can use Cinema Tools (which comes with Final Cut Studio) to convert the 24fps clips to 23.98.

 

[Johnny St.Ours]

If I am not mistaken, you can use Cinema Tools (which comes with Final Cut Studio) to convert the 24fps clips to 23.98.

Reckin I'll try and Log and Transfer the clips, then do the Cinema Tools- I tried to conform the proxies and got nowhere but green.

 

[MichaelP]

Keep in mind that slowing a 24fps file and playing it back slower will not make it in sync with audio from another camera at a different rate. When shooting (assume 48kHz) both cameras are in sync with the audio - the same could be said of shooting at 25fps, etc.

In the end, the audio to be synced with the camera changing its frame rate needs to be adjusted as well to be in sync. 24fps as 23.976 playback is a .1% slow down - the original 48kHz would need to play back at 47.952kHz to be in sync and then sample rate converted to 48kHz after the slow down.

So the question is - did each camera record its own audio, or was their a double system audio recorder as the master with cameras shooting MOS?

Michael

 

[Johnny St.Ours]

The 23.98 camera has a reference mic attached with it's own sync, the 24 camera was totally MOS. Both have to sync to the 'real' audio which was recorded by the sound engineer on some multitrack digital Pro Tools kinda setup, with whom I spoke before the shoot and told him I was running 23.98fps and 48khz.

I have not received the audio yet, so I don't know for sure which camera goes to it best, but my assumption is the 23.98 cam with the reference audio will sync right up. I was trying to figure out if the whole two camera shoot was just completely f--d. The 24fps camera is the one covering the singers face!

 

[MichaelP]

Well you are in a 50/50 situation. Editing in a 24.000fps timeline will have sync with the camera shooting the singer's face, and the other camera will drift 1 frame every 1000 frames. The reverse is true if you edit both in a 23.976 timeline. You will have to decide the master camera and sync the audio to both where one is getting a sample rate conversion. Since it is music, you will want to consider a pitch correction as well if cutting from one sound to another adjusted sound file...

Michael