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audio video sync problem

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manish choudhary
audio video sync problem
on Dec 22, 2017 at 8:26:02 am

i working on a project were audio recorded in logic pro with 48000 hz 24Bit

and video shoot on canon mark iv with ntsc 29.97 FPS

in premiere pro i import all clips and recorded video shows 48000 hz 16 Bit audio and 29.97 FPs

its a music video recorded in full HD

i trying to sync all clips with audio but in starting point of audio its matches perfectly and after playing 2-3 mins then its out of sync.

i tried different ver of audio exported from logic with no success

44 16bit
44 24bit
48 24bit
48 30bit

please help....


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Brent Marginet
Re: audio video sync problem
on Dec 23, 2017 at 3:58:25 pm

Changing the sample rate will not make a difference.

What frame rate are the audio and video at. Is the Video 29.97NDF or 29.97DF. What frame rate was the Audio Recorded at, 23.976, 24, 29.97NDF or 29.97DF. Also what frame rate are you working at in Logic. If the audio was recorded at the wrong frame rate then you will need to to a Sample Rate Conversion or SRC before it Syncs up properly. You may have to speed it up or slow it down by 0.1%. If that’s the case then you will need to do it on the Original Audio and redo your Logic Mix.

As a side note if you started off with 24bit Audio you should stay with that all the way through to the end.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more.
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Ann Foo
Re: audio video sync problem
on Dec 26, 2017 at 7:12:30 pm

The first question is, why do you need to sync audio for a music videoclip? Shouldn't you just put the music track on it and completely disregard audio?

Second question, why did you import audio at 16bit if it was recorded at 24bit? As previously stated, it's best to import at 24bit if recorded in 24bit.

This is my guess about what is happening: It's a music video. They might have shot the video in slo motion (as is often the case in music video). So, the audio will always drift. Because audio will always be recorded in real time. In this case, don't bother trying to sync all the audio files. If you need to use one bit of audio, just grab it and throw it in your cut, but you're wasting your time trying to sync full audio rushes if the video was all shot in slo motion. Either that, or slow the audio down.

NB. I know you say the video was shot at 29.7FPS so it doesn't look slow motion. But sometimes it appears that way in Premiere and needs to be manually interpreted at 60FPS or whatever to slow up properly. You should check with the cine what frame rate they shot at.


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manish choudhary
Re: audio video sync problem
on Dec 26, 2017 at 7:32:12 pm

i need to sync audio because its a vocal shoot not only music playback its a stage performance.


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Ann Foo
Re: audio video sync problem
on Dec 26, 2017 at 7:57:49 pm

Ok, so if it's not a music video clip, then as Brent says, there is likely a discrepancy between the frame rates of your audio and video. They won't sync until you make them match.


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Brent Marginet
Re: audio video sync problem
on Dec 27, 2017 at 12:31:06 am

Is the Audio falling behind or running ahead of the video.

If it's running slow you will have to do an SRC to 48.048khz or 48048hz which will speed it up by 0.1%. If it's running fast then you will have to do the SRC to 47.952khz or 47952hz. This of course is all assuming that there is only a 0.1% difference. Here are examples of Frame rate differences that will cause the 0.1% issue.

A@ 23.976 and V@ 29.97DF.
A@ 24 and V@ 29.97NDF.
A@ 29.97NDF and V@ 29.97DF.
A@ 29.97DF and V@ 29.97NDF.

If the frame rate descepincies were say 24 and 29.97DF or unlisted above then the difference will be more than a 0.1% difference. I always use ProTools to fix these SRC issues by importing the audio with SRC turned on and choosing the appropriate SRC Conversion Rate. If you want to find the Frame Rate of the original Audio Download WaveAgent from Sound Devices and drop your Audio Clips into it. It allows one to change the frame rate but as far as I know it does not do any sort of SRC. If you try anything with your Original Audio always make sure it's a copy of it so things don't end up worse than they are now.

"MY MEDIA/PROJECT MOTTO: If you think three copies of your Media or Projects are enough. Take a moment to place a value on them and then maybe add two more.
Hard Drives are now stupidly cheap. A RE-SHOOT AND YOUR TIME AREN'T."


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