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Avid Workflow for Go Pro 47.95fps Footage

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Jack Brown
Avid Workflow for Go Pro 47.95fps Footage
on Aug 17, 2015 at 10:04:13 pm

Hi all,

I very kindly offered to do a friend a favour and I am now faced with about 8 hours of Go Pro footage filmed on three cameras all at 47.95fps. Working with separately recorded audio which is 48000 with a Sound Roll TC Rate of 25 according to my bin.

My question is what is the best Avid workflow? I have ingested all the footage at 15:1s into a 25fps project but when I am creating my Sync Maps, I am noticing that clips slowly fall out of sync with clips that they are in sync at the start of the media.

Should I convert everything to 25fps before I ingest? Also, I cut a short sequence as a test and was unable to relink footage. I had to cut everything back in by eye at full res. What's the best way to conform a Go Pro sequence? I was unable to change tape name on ingest, so I changed Disk Label for my reference.

Working on AMC 7.0.4.

Any help greatly appreciated. Thanks in advance!

Jack


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Michael Phillips
Re: Avid Workflow for Go Pro 47.95fps Footage
on Aug 18, 2015 at 12:17:47 am

Which direction is the sync drift? Audio behind picture or picture behind audio?

Michael


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Jack Brown
Re: Avid Workflow for Go Pro 47.95fps Footage
on Aug 18, 2015 at 8:11:24 am

Hi Michael,

The video appears to fall behind.

Thanks,

Jack


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Michael Phillips
Re: Avid Workflow for Go Pro 47.95fps Footage
on Aug 18, 2015 at 12:10:11 pm

As you mention, the GoPro is doing the (2x 23.976) rate (47.952) rather that the full 48fps. And with picture falling behind sound, you need to either speed up picture or slow down audio. If you were in v8.4, that process has gotten easier, but in v6.x, it takes a few steps.

Picture:

Import: You need to go to console and enter "IgnoreQTrate true" and during the import, any audio will be dropped and picture comes in frame for frame. If I remember correctly, 6.x does not have a 1080p/50 project so you may need to do this in a 720p project. The other issue may be that 720p/50 may still assume a 25fps edit rate. I am not in front of a system right now to see what settings might be needing to be tweaked.

AMA: Once you AMA link and drag an entire clip to timeline, go to motion effect editor and change it to 100%. This should speed it up to be in sync.

Audio

It may just be easier to modify the sample rate of the audio to slow it down by the right amount as seen in my blog about fps, sample rate and pitch: http://24p.com/wordpress/?p=195

Take a copy of your audio files, download WaveAgent from SoundDevices.com (free) and change its sample rate to 50.052kHz (assuming it was recorded 48kHz). When importing this into Avid (check audio tab in import settings) it will get slowed down by the correct amount to be in sync with picture.



Michael


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Jack Brown
Re: Avid Workflow for Go Pro 47.95fps Footage
on Aug 19, 2015 at 7:05:04 am

Thanks Michael. That's Great advice.

jack


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