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-   -   MP3 vs WAV import / export issue..... - PT HD 12.5.0 (http://duc.avid.com/showthread.php?t=401797)

anguswoodhead 11-05-2018 12:21 AM

MP3 vs WAV import / export issue..... - PT HD 12.5.0
 
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Hi DUC guys
I rarely come here - only if I have a problem
And almost always the answer is contained within this forum
So thank you for that.

I'm running Pro Tools HD 12.5.0 on a 2010 12 Core Mac Pro with Antelope audio Orion 32+ converters

This issue has plagued me for some time.
When sending an MP3 audio file for session musos to record their part to, something goes wrong.
When they send their WAV audio file / files back to me it's slightly out of time.
I always thought it was their system or something going wrong with their import of my MP3

I finally got clarity with this issue just now after messaging with my session drummer.

I've always exported my file as an MP3 due to slow internet
They import the file
Record to it
Then send back their audio which is always slightly out of time.

So I exported the same audio file with click printed as both a WAV and an MP3
Then reimported the 2 files back into my session at the same location

Look at the image....
Top file is Original 'Bounce'
Middle file is Export of MP3 reimported
Bottom file is Export of WAV reimported

The Wav file imports at the exact same position
BUT...
the MP3 import is slightly delayed.

My deduction....
When Pro Tools exports as an MP3 something funky happens...
WHAT IS GOING ON?
Has anyone else noticed this?
Is it common knowledge?
Is there a work around?
Has this been fixed in newer versions?
Or is it some kind of 'protection' Avid have put in to 'protect' the front of the MP3?

HELP PLEASE
This has been doing my head in - for quite some time
Thanks

_JJ_ 11-05-2018 07:54 AM

Re: MP3 vs WAV import / export issue..... - PT HD 12.5.0
 
Yes indeed, MP3 files include an extra sliver of time at the beginning of the file. I don't know if it's some kind of "header" in the code, or a metadata chunk, or what, but the result is as you've described.

This is why I always insist that any mp3 audio sent to me for work must have at least one click (or any sound) out in front of the music that can be used as a sync point when importing / exporting / reimporting.

I'd be curious to know the technical reason if anybody here knows. WAV and AIFF files don't appear to suffer from this timing anomaly.


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