48 FPS Audio

[Brian Ferguson]

I was wondering if anyone has posted a workflow for audio with 48 FPS? I don't know timecode procedures or any of the synch on set etc. I think it a topic that I want to see discussed. Maybe it has and I missed it, Apologies if it has. Perhaps it is not a big deal I have not dealt with it yet.

 

[Ayan Pratap]

I may be wrong, but isn't audio non dependent on frame rates? The only thing in audio that is dependent on frame rate is the timecode?

For instance, you can record audio (with any framerate on the mixer) for a 60fps video and when you play the video back in 60fps, it would all be just fine. The only issue you may have is funky timecode on the mixer as it wasn't designed for 60fps.

If anything, audio is time dependent. Its only recording what's happening within a timeframe. The video part is just recording more detail / frames of that time frame.

Shoot 48 fps video, record audio at any fps rate, but at least 96Khz / 24bit and as long as your video stays 48fps throughout, your audio should be in sync. You will just have to manually sync all the audio as timecodes won't work..

Anyone correct me if I am wrong... would like to know..

 

[Pablo Moreno]

Audio and video in a computer environment are totally independent one another, because most software packages are designed this way already. But I probably understand why the confusion; on film, specially old film, the audio is an optical strip that goes besides the frame and is going to be affected by the speed at what the camera is running, but in modern film the audio information is digital, so that is not the case either..

 

[Ayan Pratap]

Audio and video in a computer environment are totally independent one another, because most software packages are designed this way already, but I probably understand why the confusion; on film, specially old film, the audio is an optical strip that goes besides the frame and is going to be affected by the speed at what the camera is running, but in modern film the audio information is digital, so that is not the case either..

Exactmo!

You nailed it. Film days audio mattered at how its recorded. Digitally, they are independent and as long as they are played at the rates recorded, no problem..

 

[Charles Nader]

Interesting. Never knew that.

 

[Brian Ferguson]

I guess I am wondering what they do on movies like The Hobbit to keep the 3D cameras in synch etc. The TC generators I am familiar with are all set-up for 23.98, 30 fps etc. I am guessing people are doing this I was just hoping to get some idea of how. Timecode still matters for some people.

 

[Marc Wielage]

If they shoot at exactly 48.00fps, then my advice would be to use sound timecode at 24.00 (both integer numbers). I believe this is what was done on The Hobbit, but I have yet to read a good explanation of their workflow. They synced up the dailies by just manually clapping the sticks and making sure the clap was right on the waveform spike.

I know that SMPTE has committees now working on some proposals for higher timecode frame rates (all the way to 120fps), but this will require vast changes in system architecture and hardware for sound and picture.

 

[Brian Ferguson]

Thanks Marc that was the type of input I was seeking. I guess when looking at the timecode on the footage you just have 2 frames for each 24fps code number? That would be simple enough to deal with.

I know in my old tests with Genlock on R1 there were speeds that would lock if they were multiples of the project rate, so if 24 fps was the project rate 48 should work as well.

 

[Zhang Ming]

I shot 48FPS S3d, timecode is really a big issue. The R3D clip is 24 timecode, two frames with one same timecode, many software can not handle that very well and always cause some small trouble. AVID always hang on some clips with timecode problem(but can easily solved by manually set the sync) , premiere always has problem on exporting....

 

[Elsie N]

Brian's question, which I interpreted different from his meaning, brings to mind one of my own. That is, shooting 48 fps time base at 48 fps framerate and capturing audio on camera, is the result the same as shooting shooting 24 fps (or 23.976) at 23.976 framerate? I can test this when I have the time but if someone has first hand knowledge, would like to hear. And I assume the audio is not available when you shoot at a high frame rate so that the camera treats the footage as variable speed?



Edited to clear up some confusion.