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Old May 17th, 2006, 11:30 PM   #1
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video&audio

HI AGAIN,

I made covered of an event with audio recording on location..
Can somebody give me a hint of how to do sync the audio with the video....I'm having a hard time synchronizing the sound and video....

When I did the video I recorded the sound in my cam. Canon XL2
however I have another person recording the audio ( Roland station) at the same time I was making the footage...

So, the person did the mixing and gave me the CD.
I tranfers to FCP and everything is okay the sound matchs the video...I get "almost" close to sync the video and audio but not 100% sync...

Any bright ideas?

Thanks

Janete

Last edited by Janete Taylor; May 18th, 2006 at 10:25 AM.
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Old May 18th, 2006, 01:08 AM   #2
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The process is normally easy if you use a "clapper board" or use timecode technology to "sync" the audio equipment to the video equipment or vis versa.

However, I presume you haven't done this.

My only suggestion would be to make sure that the audio is playing at the same rate/speed as the video footage. If it is not, you may start out having the audio in sync, but as time passes it will begin to mismatch.

Good luck!
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Old May 18th, 2006, 05:58 AM   #3
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Quote:
Originally Posted by Janete Taylor
HI AGAIN,

I made covered of an event with audio recording on location..
Can somebody give me a hint of how to do sync the audio with the video....I'm having a hard time synchronizing the sound and video....

When I did the video I recorded the sound in my cam. Canon XL2
however I have another person recording the audio ( Roland station) at the same time I was making the footage...

So, the person did the mixing and gave me the CD.
I tranfers to FCP and everything is okay the sound matchs the video...I get "amost" close to sync the video and audio but not 100% sync...

Any bright ideas?

Thanks

Janete
First of all, when you line up the audio track with your clip (perhaps using the audio you recorded in your camera as a guide) does it start out in sync but then gradually fall out of sync as time goes by? When you line up at the start, does the later sound lead or lag the picture?

I'm not an FCP user, someone else may be able to say yeah or nay on all this, just sharing some thoughts

First, to line up the clips import your video with the sound recorded in camera into one track, the audio from the CD into a separate audio track. Send both tracks to your speakers. As you play the clips, slip the audio file from CD back and forth to align them - as you get close it will sound like you have an echo. Nudge it back and forth until the echo disappears and they'll be aligned, then mute the in-camera audio track so only the good CD track is audible.

A consideration is the sample rate. A CD is 44.1 kHz while the camera audio is 48kHz. If the CD's sample rate didn't get properly converted when you imported it, the sound that should take 1 second to play will actually play faster, playing in only .91 seconds (at 48000 samples per sec, it takes 0.91 sec to play 44100 samples) causing the sound to fall out of sync and lead picture by 2+ frames (0.09x29.97fps) every second. So the first step is to make sure that the CD sound track is properly converted from 44.1 to 48kHz. You should be able to do that in FCP - AFAIK it should have happened automatically when you imported the CD but am discussing it just to make sure you've got all the bases covered - but if not, an audio editing application, even a freeware program like Audacity, can do that for you.

Audio programs also have the ability to time stretch without changing pitch and I presume FCP does too. Line up the sound at the start of the clip and play down to the end. If it's not aligned at the end, grab the end of the audio file and push or pull it as needed to line it up there. Don't drag the whole clip, just grab the tail end and stretch or compress it as needed.
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Old May 18th, 2006, 06:22 PM   #4
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"First of all, when you line up the audio track with your clip (perhaps using the audio you recorded in your camera as a guide) does it start out in sync but then gradually fall out of sync as time goes by? When you line up at the start, does the later sound lead or lag the picture?"

Steve:
You good.... Yes that's what is happening.... I tried to line up with the audio from the camera as a guide... as you put it so well, it start out in sync than hell breaks lose and everything is out of sync.... it's like "almost there" but not there completely...
I will try and come back later.

Chris : No " clapper board"

Thanks


Janete
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Old May 18th, 2006, 06:43 PM   #5
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What program are you using to edit with, Janete?
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Old May 20th, 2006, 10:00 AM   #6
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Fred: "What program are you using to edit with, Janete?"
A: FINAL CUT PRO 5 (FCP 5)



Steve: "First, to line up the clips import your video with the sound recorded in camera into one track, the audio from the CD into a separate audio track. Send both tracks to your speakers. As you play the clips, slip the audio file from CD back and forth to align them - as you get close it will sound like you have an echo. Nudge it back and forth until the echo disappears and they'll be aligned, then mute the in-camera audio track so only the good CD track is audible."

Yup that worked for me .... I also checked the converstion of the audio from 44.1 to 48.kHz wich was already done... So I just followed the instructions above....It was not easy but I finally got it done...

Thanks for your help.

JT
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Old May 20th, 2006, 11:34 AM   #7
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Quote:
Originally Posted by Janete Taylor
Fred: "What program are you using to edit with, Janete?"
A: FINAL CUT PRO 5 (FCP 5)



Steve: "First, to line up the clips import your video with the sound recorded in camera into one track, the audio from the CD into a separate audio track. Send both tracks to your speakers. As you play the clips, slip the audio file from CD back and forth to align them - as you get close it will sound like you have an echo. Nudge it back and forth until the echo disappears and they'll be aligned, then mute the in-camera audio track so only the good CD track is audible."

Yup that worked for me .... I also checked the converstion of the audio from 44.1 to 48.kHz wich was already done... So I just followed the instructions above....It was not easy but I finally got it done...

Thanks for your help.

JT
Glad I could help. Next shoot, so it won't be such a PITA, follow Chris's advice ... get yourself one of those old-fashioned clapper boards - "Scene 3, Take 400!" Clack! - and slate your shots. You can easily see the exact frame where the boards come together and there's a very recognizable peak in the audio waveform and it becomes easy to align the tracks in post. If you can't use one for some reason, right after you roll your shot have someone step into frame briefly and clap their hands together one time.
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Old May 20th, 2006, 10:24 PM   #8
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Thanks

I got the point...

JT
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Old May 21st, 2006, 02:37 AM   #9
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Good Morning Janete,

I'm glad you 'got the point' - but if you want to know WHY (that is always the questions) then take a look at this thread (started by yours truly):

http://www.dvinfo.net/conf/showthread.php?t=64559

Try not to get bored at first but about half the way through the thread it gets interesting.

Regards,

Dale.
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Old May 22nd, 2006, 05:33 PM   #10
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"Dale Paterson]Good Morning Janete,

I'm glad you 'got the point' - but if you want to know WHY (that is always the questions) then take a look at this thread (started by yours truly):

Try not to get bored at first but about half the way through the thread it gets interesting.

Regards,

Dale"

Hi Dale,

I went to your thread and it does make a lot more sense to me now..

Thanks for your help.

JT
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