Camera drift: audio goes out of sync...

User avatar
imagetemps
Posts: 47
Joined: Thu Sep 11, 2014 9:56 am

Mon Dec 29, 2014 8:36 pm

Hi to the community!
Did some of you have experienced troubles while trying to sync sounds in FCP after shooting at 25fps with the Kinemini? I had a long shot (49min) it gradually goes out of sync in FCP.
I convert my images via Kinestation, images at 25fps. I then do a proxy with Da Vinci, session set up and playback speed at 25. FCP set on 25. It goes out of frame.
Any idea?
Erwan Kerzanet
Last edited by imagetemps on Mon Jan 05, 2015 5:53 pm, edited 1 time in total.

User avatar
aspirepro
Posts: 22
Joined: Thu Aug 28, 2014 8:10 pm

Tue Dec 30, 2014 10:30 am

Hey again Erwan,
I have had that problem in the past with DSLR audio sync... if its the same problem and the audio goes out of sync gradually and notice obvious difference after 5 min or so, then it could be the sample rate of the audio which should always be at 48K... which sometimes it was left on 44.1K, which is the other main setting on my Tascam DR100Mkii.

If it happens gradually after about a minute, then it is probably the project frame rate in camera that might be set to 24FPS... which would mean that if the sensor FPS was 25 and the project FPS is 24 then all you have to do is modify the footage to conform to the right frame rate( I forgot how to do this in FCP, but in Premiere it is as simple as right clicking the original clip in the project finder and chose "Modify" and assume the frame rate to be"..." BTW- this is not neccesarity interpolating the footage (if the Sensor FPS is 25 then the footage is 25 FPS regardless of what the Project FPS says)

Just to make it clear-the "project FPS" is a piece of metadata that tells the NLE what the playback rate is(even transferring the metadata through Kinestation)...that does not mean that the frame rate is actually what the "project FPS" says it is... the "sensor FPS" is constant and does not change and is locked in the file despite what the metadata says.

User avatar
imagetemps
Posts: 47
Joined: Thu Sep 11, 2014 9:56 am

Tue Dec 30, 2014 3:14 pm

Hi (... and happy new year!)
Thank you for your reply.
The thing is : the duration of the .krw file matches the duration of the converted file at 25 in Cineform.
It matches also the duration of the ProRes Proxy I insert in FCPro.
BUT
When I put the CineformRaw in FC Timeline the file length is 13'08 while the original audio file delivered by the camera is only 13'07"20f !! That means that kinestation may cancel 4 fps during conversion. Unefortunatly I can't check speed with the original .krw files. Could it be possible that the kinemini cam stamps at 25 but doesn't record a real 25? so everything deals with a "fake" 25??
Erwan

User avatar
aspirepro
Posts: 22
Joined: Thu Aug 28, 2014 8:10 pm

Wed Dec 31, 2014 7:35 pm

It looks like quite the mystery to me...
I would probably try and recreate the problem and see if it happens again, checking how many frames are unaccounted for and probably rely on an external audio recorder for safety(personally I don't really trust the pre-amps on the KineMINI)

If you have checked the slate info and everything matches and still the problem persists... then you should probably report the problem with Kinefinity and keep on knocking on their door until they respond... Either they will offer you a solution or they will take care of the problem in a future firmware update( I hope)

Happy New Year to you to man!

User avatar
imagetemps
Posts: 47
Joined: Thu Sep 11, 2014 9:56 am

Thu Jan 01, 2015 11:56 am

Happy new year!

I recorded a new 5-minutes test file with a slate every minute.
The drift is 1 frame every minute. Even if I record directly in DNG (ie, I don't use neither Cineform features nor Davinci).
It might be my computer a Macbook Pro... but with an AppleProRes workflow I never experienced such drift!
To me it looks it is not a location production sound compatible camera... if this problem comes from the camera.
Did anyone experience sync sound in a professional context with the Kinemini in OS 3.2?
Best regards,
Erwan

User avatar
imagetemps
Posts: 47
Joined: Thu Sep 11, 2014 9:56 am

Sun Jan 04, 2015 5:54 pm

Hi
I just got news from Kinefinity. They say the actual firmware is set to guarantee a maximum time drift of 6 frames for 10000 frames. At 25FPS that means a professional external audio recording with a high quality quartz may be 6 frames out of sync every 6min 45 (!) It looks like what I have experienced on my time line. It is very much noticeable. I would rather say it is impossible.

They say they could reduce the drift to 1 frame every 10000 fps in a future firmware.

To be continued...

regards
EK

User avatar
Calomile
Posts: 14
Joined: Thu Sep 11, 2014 2:57 pm

Tue Jan 06, 2015 4:29 pm

I've had the sync issue and it was around 5-6 frames over the 6 minute 45 second time period that imagetemps has mentioned.

Personally it's unacceptable, even 1 frame in every 10000 is unacceptable as it means you'll be noticeably out on a recording longer than 18 minutes.

As it stands right now, even doing sync sound is out of the question unless you like having gaps in your audio as you have to shuffle the sync back. Completely unprofessional.

User avatar
George A.
Posts: 19
Joined: Mon Aug 25, 2014 7:30 pm
Location: Finland
Contact:

Wed Jan 07, 2015 12:56 pm

Thanks for you guys sharing this. It is really useful. I don't understand how camera companies still manage to mess up audio even though it seems to the simplest part to the camera! I don't see mics developing nowhere near as quick as sensors.
Kinemini 4K, Canon 5D4, Canon C100MKII

User avatar
imagetemps
Posts: 47
Joined: Thu Sep 11, 2014 9:56 am

Wed Jan 07, 2015 7:31 pm

They don't mess with audio... they messed with the camera itself!

User avatar
George A.
Posts: 19
Joined: Mon Aug 25, 2014 7:30 pm
Location: Finland
Contact:

Thu Jan 08, 2015 9:55 am

I did a small test to see how bad it gets.

Kinemini 4K, Canon 5D4, Canon C100MKII

Post Reply
  • Information
  • Who is online

    Users browsing this forum: No registered users and 1 guest