AAF / OMF Question

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Yannick
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AAF / OMF Question

Post by Yannick » Tue May 07, 2019 9:02 am

Hi all,

An editor sent me both AAF and OMF files from Adobe Premiere for me to mix.

They are 48/24.

He also sent me a rendering of the edited video with stereo audio embedded.

The AAf and OMF open fine in Nu10 but when I import the video (and extract audio file for reference) and drop them in the project both the AAF and OMF files are exactly 44ms late.

Not a showstopper since once I correct the offset everything is in sync...any idea why this is happening ?

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Yannick

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Fredo
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Re: AAF / OMF Question

Post by Fredo » Tue May 07, 2019 9:20 am

Audio from a video file should/can NEVER be the reference.

I sound like a broken record, but how difficult can it be to incluce a white frame & audio 2pop in a project.
Everybody knows that sync is crucial.
Everybody knows that sync is *always* a problem.
And still, what once was standard procedure seems to be forgotten*.

* Read: Lazyness/ignorance/couldn't care less-ness.

Fredo

Yannick
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Re: AAF / OMF Question

Post by Yannick » Tue May 07, 2019 9:40 am

Fredo wrote:
Tue May 07, 2019 9:20 am
Audio from a video file should/can NEVER be the reference.
Agreed, but still, with the offset correction I get sample accurate phase cancellation until the very end of the video (put aside the data compression artefacts of the embedded audio of course).

The audio extracted from the video is in perfect sync with the video and all the audio from either the OMF of the AAF is not in sync with the video.

Agreed the rendered video and the AAF / OMF should include a sync.

I would still like to know if there is a rational explaination for this 44ms offset if someone has already experienced this ?

- can it be on the Nuendo side when importing OMF / AAF ?
- a Premiere thing when creating OMF / AAF ?
- a Premiere thing when rendering the video ?

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Yannick

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fuzzydude
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Re: AAF / OMF Question

Post by fuzzydude » Tue May 07, 2019 9:43 am

Yannick wrote:
Tue May 07, 2019 9:02 am
Hi all,

An editor sent me both AAF and OMF files from Adobe Premiere for me to mix.

They are 48/24.

He also sent me a rendering of the edited video with stereo audio embedded.

The AAf and OMF open fine in Nu10 but when I import the video (and extract audio file for reference) and drop them in the project both the AAF and OMF files are exactly 44ms late.

Not a showstopper since once I correct the offset everything is in sync...any idea why this is happening ?

Regards
Yannick
Like Fredo said, go back to the editor and ask for it, since it appears they likely don't know about it. I'd also get them to add one at the end for safety, just in case there's any drift.
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Fredo
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Re: AAF / OMF Question

Post by Fredo » Tue May 07, 2019 11:41 am

Yannick wrote:
Tue May 07, 2019 9:40 am
I would still like to know if there is a rational explaination for this 44ms offset if someone has already experienced this ?
I'm an old fart, and getting lazy.
Luckey, Sagi-good friend and creator of the extremely handy- "ER Media Toolkit" has explained this in detail in the ER Media Toolkit User Manual.
I hope Sagi doesn't mind that I copy/paste this part here.

About the option "Auto Fix Offset Issue"


Auto fix audio offset issue’ (enabled by default). Introduction and background: Due to extensive video decoding time some highly compressed and complexed codecs are designed to offset their included audio streams to ‘force’ video audio playback synchronization while played in their native form through various media players in various devices, However, converting those codecs into none compressed form may introduce the opposite result! Therefore, we designed a unique smart algorithm that detects those potential offset problems in both input and target audio/video and only if necessary adjust intelligently the audio stream offset to keep it 'in sync' with the target video, resulting in less than 1ms (less than 45 samples) sync accuracy between video and audio streams with most popular mp4 but never ever risking adjusting into negative values that result in audio material beginning cutoffs (as you may experience with most other conversion algorithms that try to deal with that issue). This fix applies to AAC and MP3 audio streams, all other codecs unaffected in this process. If you choose to disable this option the audio will not be analyzed and processed with this unique algorithm and shall be passed on exactly as it originally created in the source media (this method is unique for ER Media ToolKit in both Video and Audio conversion or ‘Extract Audio to Wave’)


Do yourself a favor and download ER Media Toolkit and donate.

Fredo

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Re: AAF / OMF Question

Post by Yannick » Tue May 07, 2019 11:51 am

Many thanks, I'll dig into that.

Regards
Yannick

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Re: AAF / OMF Question

Post by uarte » Tue May 07, 2019 8:16 pm

Fredo wrote:
Tue May 07, 2019 9:20 am
And still, what once was standard procedure seems to be forgotten*.

* Read: Lazyness/ignorance/couldn't care less-ness.

Fredo
Yup, I still always do a round-trip test with frame markers and test audio pops/beeps with all my clients when we begin a new project, and to this day, quite often, I still find sync problems from their files. Codecs and rendering differences are usually to blame. Better to spend the time to catch it early and get the round trip process perfect with each client, then you can trust your AAFs and OMFs.

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Re: AAF / OMF Question

Post by ltf3 » Wed May 15, 2019 2:19 am

Thanks for this Fredo!

For what it’s worth I insist my video ref file ( with editors ‘mix’ ) be exported as QuickTime ProRes LT ( or Proxy ).

Haven’t had a sync issue in years!. Don’t use MP4 / H264 as a sync reference.

Plenty of ProRes support on Windows returning too, so that’s good!
Lee

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Re: AAF / OMF Question

Post by GNP » Sun Jun 16, 2019 7:44 pm

Fredo wrote:
Tue May 07, 2019 11:41 am
Yannick wrote:
Tue May 07, 2019 9:40 am
I would still like to know if there is a rational explaination for this 44ms offset if someone has already experienced this ?
I'm an old fart, and getting lazy.
Luckey, Sagi-good friend and creator of the extremely handy- "ER Media Toolkit" has explained this in detail in the ER Media Toolkit User Manual.
I hope Sagi doesn't mind that I copy/paste this part here.

About the option "Auto Fix Offset Issue"


Auto fix audio offset issue’ (enabled by default). Introduction and background: Due to extensive video decoding time some highly compressed and complexed codecs are designed to offset their included audio streams to ‘force’ video audio playback synchronization while played in their native form through various media players in various devices, However, converting those codecs into none compressed form may introduce the opposite result! Therefore, we designed a unique smart algorithm that detects those potential offset problems in both input and target audio/video and only if necessary adjust intelligently the audio stream offset to keep it 'in sync' with the target video, resulting in less than 1ms (less than 45 samples) sync accuracy between video and audio streams with most popular mp4 but never ever risking adjusting into negative values that result in audio material beginning cutoffs (as you may experience with most other conversion algorithms that try to deal with that issue). This fix applies to AAC and MP3 audio streams, all other codecs unaffected in this process. If you choose to disable this option the audio will not be analyzed and processed with this unique algorithm and shall be passed on exactly as it originally created in the source media (this method is unique for ER Media ToolKit in both Video and Audio conversion or ‘Extract Audio to Wave’)


Do yourself a favor and download ER Media Toolkit and donate.

Fredo

Very useful information, I didn't realize ER did this as well! Thank you.
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Heiner Einbier
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Re: AAF / OMF Question

Post by Heiner Einbier » Thu Jun 20, 2019 2:17 pm

A lot of times, the video editor will export the preview file as H.264 with a variable frame rate. This will reliably play merry f*ckin' hell with the sync, as well as make it impossible to frame-accurately detect cuts. Good editors know this and will either export a file with a decent intermediate codec or a H.264 with a constant framerate. They'll also include 2-pops.
Bad editors need to be taught this. With a blunt instrument if need be... :mrgreen:
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Stevan
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Re: AAF / OMF Question

Post by Stevan » Fri Jun 28, 2019 11:11 am

Did somebody notice that OMF import navigation folder is changed in Nuendo 10?
In previous versions after the first saving of the project and clicking 'Import OMF' the project folder was appearing by default.
In version 10 when importing OMF Nuendo navigates you to the folder of the last imported OMF.
I know this could be trivial for the most of people, but this is really a time-consuming process for all of us who import more than one OMF per day...

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